Softrock Lite 6.2
Adventures in Electronics and Radio
Elecraft K2 and K3 Transceivers
October 2006 Archive
Question for my Elecraft K2 Readers
I can now see the end of the Z90 kitting process and
it's time to think about some follow-on projects. It seems that the main
community of kit builders center around Elecraft, and mostly the K2.
What kits would you like to see that are not currently
offered by Elecraft or other suppliers? I'm thinking of K2-related ideas, but am
not necessarily limited to that. And, since I've grown rather fond of
programming 18F PICs using Swordfish, the project should use a PIC someplace.
Drop me an E-mail with your thoughts. No promises, and I
have some ideas of my own that may or may not pan out, but I would like to know
what is on the K2 Elecrafter's wish list.
And, no I don't think that I can design and offer a
version of the mythical "K3" general coverage receiver equipped transceiver,
with 160-6 meter coverage and 100 watts output built in. It would be an
interesting project to try, and I have some receiver ideas, but it's way, way
beyond what I'm thinking of.
I'll leave this question at the top of the updates page
for the rest of the month.
31 October 2006
Today was mostly a paperwork day, including more editing
of the Z90 documentation and printing copies to be bound into the documents
shipped with the kits.
Stan, W5EWA, has an interesting report on Stage 5 that can
be read by clicking here and scrolling down. Based
on his experience and the similar experience Bob, K7HBG, also reported today,
I've decided to go back to the original design's over-current protection, a 1.1A
polyfuse. I've discussed the issue in my comments on Stan's report, so I won't
duplicate it here. However, this is exactly the reason to conduct a limited
pre-release build. It's much better to make a change now, before the kits are
30 October 2006 PM
Today involved a bit of metalwork. I punched PCB mounting
holes in 10 chassis pans. To quickly and accurately locate the six holes
required in each chassis pan, I made a template that attaches to the chassis pan
via four existing holes. I then use a transfer punch to mark the six holes to be
punched. Then, I use a Roper-Whitney XX punch to make the 1/8th inch holes. The
result is a clean, round hole with a minimum of burrs. While I was punching the
holes, I knocked the sharp edge off the sheared end with a file. Still, use
sensible caution when handling the chassis pan, as it will still have burrs and
I also did a bit of experimentation with various size
boxes. The Z90 and Z91 kits are shipped in a 12x12x8 inch cardboard carton.
Inside that are two (I think, based on today's work) boxes. One is 10x10x3
inches and holds all the enclosure-related parts. It also will hold the optional
power supply "wall wart" unit. I think the Z91 may fit into a 10x10x2 inch
sub-box, but all my experiments today were with Z90 enclosures.
The electronics will be in a separate 10x10x3 or 10x10x4
inch box. It's a tight fit into a 3" box, so I likely will use a 4" box with
I've also been searching for a way to provide a serial
number plate and have found a solution. The kit will come with three small tags
printed on polyester base with the serial number and your callsign. These have
an aggressive adhesive and once in place are hard to remove. Being polyester,
they are not subject to tearing like a paper tag. The kits will ship with three
serial number tags, one for the PCB, one for the temporary back panel or
enclosure bottom, and one for the final back panel.
I also programmed some 18F4620's with the current Z90
firmware to ship with this week's kits. The firmware can be updated as new
releases may become available, of course, via the Z90's serial port and
bootloader software. I also made a simple test fixture from a Z90 front
panel and checked all the upper and lower struts I made for fit. All passed this
test. Two struts are reserved for my use, as I made errors with them that
resulted in extra drill holes. (It's hard to mess up when using a milling
machine with a digital readout, but I misread 0.100" as 0.000" a couple times.)
Those struts are fine, but the extra holes are not right, so they will stay here
for my use.
I also revised the Assembly Manual to incorporate the
three-page addendum that I sent to Stan and Bob for their pre-release kits.
Stan may provide a later construction update and if so,
I'll post it tomorrow morning.
30 October 2006 AM
I posted Stan's Stage 4 results this morning and also
added his Stage 2 comments that I had overlooked.
I've also added the grid reference document to the
Documents page. Or, you may click
here to view it.
29 October 2006
I finished enough struts to fill this week's orders. I
will go through them and test fit to a Z90 panel to verify my work.
Stan, W5EWA, has finished Stage 3 of the pre-release
build. I've added a page with his photos and comments. You may view the page by
clicking here or via the navigation menu at the
top left of this page.
28 October 2006
I made up the "Dropsies" bags this morning. The contents
includes surface mount parts for the Z90 and the Z10000-K2 & U buffer
amplifiers. Between the parts in the Dropsies bag and the extra gain setting
resistors in the Z10000 kits, you should be covered for lost SM parts. It also
includes hardware extras. As a courtesy, the hardware spares included with the
Dropsies bag will be provided to all international purchasers as it can be
difficult to find 4-40 hardware in a metric country.
I started making the Z90 struts. I cut up 60 some feet of
1/2" x 1/2" Delrin stock into 9 inch segments, trimmed to length and then milled
a dozen or so to the correct thickness. At that point, I got a bit careless and
nipped a finger. It's difficult to work (and to type) with a band aid on my
fingertip, so I turned the mill off for the day. I'll get back to it tomorrow
and at least finish enough struts to take care of this weeks shipments.
Photos of the struts under manufacture will be posted
tomorrow when I can type with all 10 fingers.
27 October 2006
If you have not done so, please read the Update on
Delivery Schedule at the top of this page.
Mr. Murphy, of Murphy's law fame, paid a visit this week.
The parts with the longest lead time, the front and rear panels, turn out to
have a problem--unacceptable paint quality in about 80-85% of the parts. In
discussing the problem with Emachineshop today, it turns out that they had also
done a quality check of the panels and knew of the problem, but shipped them to
me without a comment.
The panels will be replaced without charge to me, but as
mentioned in the Update on Delivery Schedule, not until mid-December or so. I
will ship kits, if the customer agrees, with the panels I have and will supply a
replacement as soon as I receive them and they pass my inspection. Or, I will
wait and ship a complete kit with good panels later this year. If you are a
customer and have not provided me with your option, please drop me an E-mail
message with your choice.
This problem is more than a bit irksome as I was looking
forward to providing a good looking product and getting the kits into the
builder's hands within the next week or so.
So far, about half the responses have been to go with the
existing panels. I appreciate that vote of confidence.
Yesterday and today have been consumed with this problem,
including unpacking and repacking a bit over 100 individual panels. I will be
back to a normal schedule tomorrow, I hope. I plan to start on machining the
upper and lower support struts. It's more than a single day's job but I can at
least make a good start on it tomorrow.
I also will try and post an update to the Swordfish DDS
page over the weekend. I know that I'm behind on my postings there. When the DDS
page is finished, I will try the inverse -- explain how one does
analog-to-digital conversion with Swordfish and an 18F-series PIC.
25 October 2006
One open issue on meeting all the Z90 orders involved a
few un-delivered BK-959 enclosures from
TenTec. TenTec's enclosure sales manager, Jim Wharton, offered to repaint
enough of their existing blue stock to meet my requirements and I accepted that
offer today, as the earlier than expected front and rear panel delivery has
accelerated my delivery schedule. Dealing with TenTec on the enclosures has been
a positive experience and if you are in the market for standard or custom
enclosures, I recommend them.
The BK959 (Z90) and BK929 (Z91) enclosures are expensive,
but are very high quality, all metal enclosures. A significant fraction of the
cost of production is represented by the enclosures and panels. Indeed, about as
much money goes into the enclosure-related hardware, including contracting
services such as shearing the chassis pans, as goes into the electronic parts of
a Z90 or Z91, excluding, of course, the Z90's graphical LCD module.
I had several hardware parts bags short a few 4-40 screws
and DB9 jackscrews. Those parts arrived yesterday and were added to the missing
parts to the kit bags this morning. That should represent the absolute end of
adding parts to the existing bags, absent some oversight on my part.
I'm going to knock out more revisions on the Operation
Manual tonight. Today has been consumed with many small tasks that make it
difficult to generate the sustained concentration required for writing. Today's
tasks included establishing a Clifton Laboratories checking account, should
anyone prefer to write their checks that way. It also included a visit from the
termite inspection company, who confirmed that we have some infestation. It
seems early enough that structural damage is not an issue, but the original
ground treatment applied when our house was built 20 years ago has dissipated.
Based on my experience packing the two early build kits, I
ordered more internal boxes, so that inside the main 12"x12"x8" cardboard box
will be at least two smaller cardboard boxes; one containing the enclosure and
the second the electronic parts. Within the electronic parts box will be
sub-boxes for the more fragile parts, such as the GLCD, the GLCD inverter and
the DDS module. Plus, of course, the ubiquitous foam packing peanuts and
bubble-wrap. With the fragile parts thus triple boxed, I do not anticipate
24 October 2006
I received a surprise today�the UPS man delivered the Z90
and Z91 panels. They fit as intended and this means that the kits should be
ready to start shipping early next week, assuming Bob, K7HBG and Stan, W5EWA,
don't find major problems with their pre-release builds. Based on how well my
pre-build went from random kit bags, I'm not anticipating anything more than
some fixes in the documentation. I know the Assembly Manual needs new
photographs in a couple places showing the final panels.
Today I also started revising the Operating Manual. It's
another couple days work to finish that, and to work in the new photographs,
print the documentation package and have it coil bound.
The panels are 0.062" steel, by the way, and were laser
cut. The cuts are smooth and straight. Being steel, they are heavy. The color
may not translate well through the Internet. It's a light gray powder coating,
with a matte finish. You can see the texture when viewing the panels in person.
The lettering is black and red.
Here are the photos. I'll make these a bit larger than
usual and not add captions. Clicking on an image will give the full resolution
23 October 2006 PM
I packaged one complete (except for front/rear panels) Z90
this afternoon. I'll ship it off to Stan, W5EWA, in the morning, and I'll send
Bob, K7HBG, his advance Z90 Wednesday, after the rest of the shipping and
packing material arrives. Assuming things like work and the real world don't
intervene, I hope to receive their comments on the build and documentation
beginning this weekend.
The next couple weeks have some house-related activities,
including new storm gutters and a visit to the landscape advisor at Betty's
Azalea Ranch in Fairfax.
http://www.bettysazalearanch.com/ The idea is to fill in the gaps caused by
the tree trimmers cutting down the overgrown bushes and trees. I will continue
working on various Z90 projects between these other activities.
The 1800 uF/25V electrolytic capacitors arrived today and
I went through all of Stage 1 bags and replaced the 82uF/63V components with the
larger value parts. Tomorrow should also see arrival of the 4-40 hardware and,
fingers crossed, I should be able to complete the last bagging and tagging.
On the meteor scatter front, I hauled out my Icom R7100
VHF/UHF receiver and set it to LSB mode and dialed in the aural carrier
frequency for Channel 2, no offset, 55.250 MHz, setting the receiver 1 KHz high
to get an audible beat note. My R7100 is not nearly as stable as my Racal
RA6790/GM which can be parked on a frequency and will stay within 1 Hz all day.
I don't expect the R7100 to steady down until it runs for a day or two.
My reading of the FCC's channel assignment table says the
nearest zero offset Channel 2 TV station is New York City. That should be close
enough to see some aircraft trails as well as meteor pings. Baltimore's Channel
2 station is a + offset, so it is 10 KHz above 55.250 MHz. Channel 2- offset
stations are found in Pittsburgh PA, Greensboro NC and Nashville TN. I can hear
signals there but Channel 2 zero offset is stronger.
The offset of -10, 0 and +10 KHz is an interference
control measure, by the way. The idea is that if your TV set should receive
interference from an undesired co-channel station, the intentional frequency
offset causes less objectionable closely-spaced herringbones, rather than broad
black bars including potential synchronization loss. (Stations with identical
channels and offsets are spaced much further apart than stations with identical
channels but different offsets.) With so much TV being sent via CATV, there is
probably a generation of folks that don't appreciate the problems of co-channel
Here's a 55.250 MHz signal capture. As you can see,
the R7100 is drifting, about 12 Hz over the space of the data capture (504
seconds). The main carriers are the bright white lines sloping downward due to
receive drift. The weaker tracks are aircraft reflections. The ticks are 20
seconds, so knowing the carrier frequency it is possible to compute the aircraft
speed from the Doppler shift. The curving tracks represent changed relative
speed; as the geometry of the Channel 2 transmitter, my receiver site and the
aircraft changes, the relative speed changes even if the aircraft maintains the
same ground track and ground speed. And, of course, aircraft also change speed
There's a serious use to which this type of data and
analysis can be placed. What the image reflects is a primitive "bi-static radar"
arrangement, where the radar transmitter (the TV broadcast station) and the
receiving site (my QTH) are separated by large distances. With knowledge of the
exact locations of the transmitter and receiver location, and better frequency
measurements (and, preferably data from multiple transmitting and receiving
sites) it is possible to determine the location of the aircraft generating these
tracks, to a highly accurate degree.
This become important, according to the open literature,
in detecting aircraft employing stealth technology. Stealth is apparently
exceedingly effective at typical microwave radar frequencies. But, at lower
frequencies, such as the TV low band and FM broadcast band, it becomes
considerably more difficult to vanish from radar screens. Rather than small
parts of the aircraft reflecting signals, the entire airframe radiates, or at
least a significant part of the airframe radiates.
23 October 2006 AM
I ran the ARGO spectrogram program overnight, connected to
my Racal RA6790/GM receiver, tuned to CHU at 14670 KHz. The antenna is a 25-1300
MHz discone at 85 ft above ground, normally used for VHF/UHF listening.
The Orionid meteor shower was still present last night and
early this AM, I believe. I'll post a couple of the more interesting images.
An excellent tutorial on interpretation of spectrogram
images of meteor scatter can be found at
The following two images are in time sequence. Note the
"E" shaped artifact in the first image and the intense bursts of strong
signal in both. As I understand it, vertical lines are distinctive signatures of
meteor trails--very high Doppler rate. The stranger artifacts are propagation
from the trail of ionization left by the meteor and may last many minutes and
will exhibit Doppler as the trail dissipates, and multi-path propagation, as
seen on these images and the ones Ron, K8AQC, collected a couple days earlier.
The reflective trails are at about 60 miles (100 km) elevation from what I've
Two more images in time sequence.
22 October 2006
I ordered the a few remaining hardware items today, as I
ran out of 4-40 x 1/4" screws and Nylon washers. I also ordered the boxes and
some packing material and finished the packing list document. The kits will ship
in a 12"x12"x8" box. I packed a sample Z90 kit this morning and that size box
Ron, K8AQC, sent along two more spectrogram images of
CHU's 14670 KHz signal.
The image below represents normal "no signal" propagation
mode. Traces of CHU's carrier can be seen intermittently.
The image below has some very unusual propagation
paths. Note that the signal has shifted 2 Hz or so and there are two distinct
strong traces. This is likely multiple anomalous paths or a single reflective
path that is changing height, so that the result is a Doppler-shifted signal. I
don't pretend to know how to interpret these images, but it seems clear that
something unusual is going on. The unusual propagation conditions hung around
for several minutes.
21 October 2006
I bagged and tagged most of the Z90 hardware today. I ran
short on 4-40 x 1/4" machine screws and Nylon washers, so I won't complete that
job until Tuesday when the additional parts arrive. I also have most of a
check-list assembled, identifying all the various separate bags or assemblies
that should be packed for a Z90 or a Z91. I also stopped at the UPS Package
store and picked up a couple of 12" x 12" x 8" boxes to see if that size is
suitable for the Z90 and Z91. I'm sure it is but the real test will be when I
use them to send out the two pre-build kits next week.
At this point, the kitting process is almost 100% done. I
have to pack the integrated circuits, and before I can do that I need to program
the 18F4620's so I plan to do that after I make a couple small changes to the
firmware next week.
On the normal ham radio front, I have an interesting image
I received from Ron, K8AQC, an old friend from the Detroit area.
The image is a spectrogram of CHU at 14670 KHz, as
received on a TenTec RX320D, early this morning during the
Orionid meteor shower. The signal burst
about one-third from the left edge is a remarkable signal reflection from a
meteor trail, I believe. CHU is not audible at that hour on that frequency in
Allen Park, and the only signals received are from various indirect propagation
paths, such as aircraft reflections and meteor trails and scatter. Contact Ron
directly at firstname.lastname@example.org if you
wish to know more about the image.
In addition to the Z90 work, I re-installed my 80 meter inverted vee after the
tree trimmers put up the wire supports Thursday. That antenna has been up nearly
20 years and used plastic end insulators. When I climbed the tower today to
attach the new Dacron support rope to the insulators, I found that the outer
layers had turned to a chalk-like substance to a considerable depth. I imagine
it is the effect of ultraviolet light, but I did not trust their mechanical
integrity, so I replaced them with porcelain egg-type insulators. I know that it
isn't considered good practice to use compression-type insulators on dipole
ends, but I've done it successfully on many antennas. And, I used a good size
compression insulator with a leakage path that's longer than the old plastic
I ran a series of sweeps with my HP8752B vector network analyzer
after re-hanging the antenna. Here are a couple of the more interesting ones.
SWR from 3.5 to 4.0 MHz. When installed, I cut the antenna to be resonant
around 3.6 MHz as my most common mode of operation is RTTY. That resonant
point is still present. The 3:1 SWR point on the upper end is 3862 KHz. With
the FCC's most recent frequency changes, it looks like it will be good for SSB
Smith chart as displayed on the HP8752B.
I also ran a sweep
on my M2
7-10-30LP8 "Skip" Log Periodic antenna. It's at 100 ft above ground and
provides continuous coverage 10-30 MHz and also a segment of the 40 meter band.
SWR plot of the log periodic. The red reference line is 2:1 and the antenna is
below 2:1 over the range 9.5 - 30 MHz and about a 150 KHz segment of the 40
meter band. The plot's frequency axis is logarithmatic, so the frequency lines
are 7, 8, 9, 20, 20 and 30 MHz.
This is the second log periodic antenna I've used. The first was a KLM
skip-band log periodic with similar frequency coverage. It lasted about 17 years
but, as Matt Strelow, KC1XX, owner of
XX Tower, said when he did the
replacement job, "the aluminum got tired" and it was falling apart. The
M2 antenna has higher quality construction and I expect it to last longer.
These compact log periodic antennas are adequate performers, and work as well as a
typical three element trapped tri-band beam for most purposes (not as much F/B
as a tri-bander) but permit full frequency coverage with a single antenna.
20 October 2006
I've started to bag and tag the hardware and miscellaneous
items. I should complete most of it over the weekend, although machining the
Z90's struts will take a bit longer. I cut the tin plate for the log amplifier
shields today. I have a large guillotine-type paper cutter that I use for
cutting PCB material. It did a nice job with the 0.008" tin plate as well.
I've had a chance to work more with the power supply
(wall-wart type) that I will provide as an option for purchasers. I purchased
and evaluated two power supplies. One is a very nice, small, efficient switching
supply, with universal voltage acceptance (100V to 240V, 50/60 Hz). The other is
of standard analog design and works only with 120V, 60 Hz.
After listening tests and some spectrum analyzer work, I
can only recommend the switching supply if your antennas are remote from your
receiver. Like all switching supplies, it generates broadband trash. Some of it
can be reduced with a common mode choke at the power supply, but there's still
pickup on the antenna unless it is some distance away and connected via coaxial
cable. Consequently, I'll provide the switching supply only if someone insists
on it. I'm disappointed, as my early tests showed it to be relatively noise
The linear supply has no trash problem, but of course it
is not as efficient and it is somewhat larger. Those are small prices to pay for
reduced noise, of course.
I was supposed to receive the graphic LCD modules
yesterday. When they did not arrive, I checked with Crystalfontz and found that
they had not yet been shipped. That problem is now corrected, and the displays
are en-route, to be delivered Monday.
After working with the production PCB for a week, I made a
couple of small changes in components. The kits that ship will have the changed
components. The main changes are increasing the value of the electrolytic
capacitor in the power feed to permit improved operation where the power source
has high ripple levels. My original design assumed a close to pure DC power
source and it's apparent that isn't necessarily the case. I also increased the
size of the heat sinks on the two 7805 regulators. The hottest temperature
measurement with the old heat sink was 171°F and with the new, larger one, the
highest reading is 134°F. I've run prototype units for the last six months with
the smaller heat sink without a problem, but cooler is better. The DDS board
runs about the same temperature, 130°F or so, a reasonable temperature for these
19 October 2006 PM
The tree service showed up a couple of hours late, but jumped into work
immediately. The trees intruding into my tower and the guy anchors are now a
memory. And, my inverted vee end attachments were installed about 45 feet in the
air. One pine tree and one oak tree. That won't make much of a difference in the
signal, I imagine, as the center is at 80 feet and the trees are quite some
distance from the end of the wire. Still, it's a better installation than
before. What remains is to climb the tower to the 20 ft level and attach the new
support Dacron rope to the end insulators. I may have to snake one inverted vee
end around the lowest guy wires as well.
On the Z90 front, the DDS modules arrived today from Mike at Kit Builders. I
checked all the assembled units by plugging them into one of my Z90 units and
found 100% functional.
I also prepared a hardware list for the Z90 and Z91 kits. This is an update
of my general hardware spreadsheet to reflect things that I had overlooked, such
An AD9851 installed on a Z90 DDS module by Mike at Kit
Builders. This is a much nicer soldering job than I can do on AD9851 size
19 October 2006 AM
I finished the Z90 Assembly Manual, version 2.0. It's
quite a bit better than version 1.0, even if I do say so myself. It has almost
all new photographs, showing the production PCB. It also includes the Z90 stages
(the earlier manual was Z91-oriented.) It's available for download by clicking
here, or from the
In order to keep the document at a manageable length for
download, I've selected 96 dpi graphic resolution. Purchasers will receive a
paper copy of the manual and a higher resolution PDF version on CD-ROM.
Version 2.0 is a lengthy document, 96 pages, and in the
original Microsoft Word format about 215 MB. While I like Microsoft Word, it is
grossly inefficient working with larger files. It takes close to two minutes for
an auto-save. And that is on a computer with 2 GB RAM.
I'm expecting the tree service company to arrive today to
remove some trees that have grown to the point where they are interfering with
other things. A couple are near my tower and guy wires and others to be removed
are blue spruce trees that were cute little things when planted 20 years ago but
are now 30 feet tall and obscure the front of our house.
While the tree service is here, I'm having them install
antenna supports for my 80 meter inverted "V" antenna. The ends are presently
supported at about 20 feet above ground, as high as I could reach
with an extension ladder.
18 October 2006
Another long day, started at 0530 and it's nearly 2000
now. Other than a couple of short trips to the train station to drop off my wife
and pick her up, I've worked on the Z90 project all day.
I made four sets of struts from Delrin square stock,
experimenting with techniques that will speed up producing the number needed for
the Z90 deliveries. The four sets will permit me to ship out two test assembly
kits later this week and allow me to assemble a Z90 in a cabinet as well. None
will have front or rear panels, of course.
The remainder of the day has been spent in further
photographs and revisions to the Assembly Manual. The remaining part to write is
the Z90 cabinet assembly. I hope to knock that out in a couple hours tomorrow.
The first real PCB assembled and in the Z90 cabinet, before
the display and switch boards are mounted.
17 October 2006
I picked up the sheared chassis pans from the sheet metal
shop this morning. They look good, nice clean cut with just a trace of a lip. I
also received the "linear grommet" material and verified that it fits over the
chassis pan edge.
The rest of the day was devoted to revising the Assembly
Manual. I have now finished all of the electronic stages and the remaining
sections relate to assembling the chassis, struts, displays and the like. I
cannot finish that until the front panels are here, but I will wrap up the rest
of the text tomorrow.
I also received a note that the DDS modules have been
completed and were shipped to me today. I should have them before the end of the
week and can test their functionality. My fingers are crossed, as these are VERY
expensive modules, considering the parts and assembly charges. I used Mike,
WA6OUW, at Kit Builders to do the DDS assembly, as he has extensive experience
with the similar DDS-60 module.
16 October 2006
I've spent most of the day working on updating the Z90
Assembly Manual. I have 100 or more revised photographs to work into the
document, and at least as many text changes, expansions, deletions and general
clean up work to do. I hope to have that finished by Wednesday evening and will
post it on the Documents page when completed.
In addition to new front and rear panels, the standard
TenTec BK-series enclosures require a modified chassis pan in order to provide
room for the Z90's display and, in the case of the Z91, to provide access for
the front panel LED. This requires trimming 1 inch (25 mm) from one side of
TenTec's stock chassis pan. (The chassis pan is the horizontal aluminum
structure to which the PCB is attached with stand-offs. It's shown in the middle
photograph of 15 October.) I've cut the 1" strip with my metalworking bandsaw in
making the prototypes, but the result required a great deal of cleanup afterward
to remove burrs. I opened all the TenTec boxes this morning and removed the
chassis pans and delivered them to a large sheet metal shop near Dulles Airport
today. They will trim the 1" strip using a power shear, and they did one sample
for me while I was there. The edge is very nice, no burrs. The rest of the
chassis pans should be finished tomorrow. This may seem like a small task, and
it is, but by the time it's finished, it will have consumed about six hours, all
I also asked the sheet metal shop to shear the 0.008"
(0.2mm) tinplate stock for the log amplifier shield. This may not be possible
with their equipment, as it is so thin and flexible that it bends rather than
shears, or if it does shear, it will is with a bent edge. If it can't be done
with machinery, I will cut the shield strips with hand shears. I received a
short lesson on how to do that job without burs and bends while hanging around
the shop waiting for the sample to be cut. The trick is to (a) use shears that
do not have a serrated edge and (more importantly) (b) take small cuts, with the
work near the hinge. Don't cut more than 25% of the jaw length in any single
The 0.008" stock is thin enough to be cut with a stout
pair of scissors. Part of the builder's job is to bend the 1" (25mm) strip of
stock into an open-top box, solder the edge together and then solder the
completed box onto the PCB. Depending on how good you are at making bends in the
strip, you may need to trim a bit off the supplied length.
If you really botch the job, stop at the local hobby shop
that sells model airplanes and look for the metal stock area. 0.008" Tinplate
should be available in 4" x 10" lengths for a couple dollars. That's where I
obtained the supply for the Z90 kits, via the Hobby Hanger in Chantilly VA.
happens to be located next door to Dancon electronics parts supply so I usually
look around the Hobby Hanger when I visit Dancon. Hobby shops are a good source
of some small tools and parts, such as short lengths of brass and aluminum
stock, 0-80 hardware and the like.
15 October 2006
I finished the remaining stages shortly after lunch today.
Total time between 10 and 11 hours, including photographs and annotating the
assembly manual. I believe the extra time involved in documenting changes in the
assembly manual offsets my experience in building Z90s, so your time will run
about the same. The Z91 will be a bit shorter, by perhaps an hour or so.
I had no problems with the build. Everything worked as I hoped it would.
By the way, I found a source of 6-32 black oxide pan head
screws at Fastener-Express.
http://www.fastener-express.com/ My usual sources, such as McMaster Carr or
MSC do not carry this length.
The completed Z90 in the enclosure, without the front and
rear panels and the top and bottom covers. It's running but no signal is
connected. The top and bottom struts support the display and soft key board
and allow the front panel to be made without screw holes, other than at the
Rear view looking at the display module. The front edge of
the chassis pan will be covered with a plastic edge protector to prevent
chafing the 20-pin ribbon cable. The cable is intentionally short to reduce
Completed PCB installed. The DDS module (on the left) is an
earlier prototype. I'm expecting the assembled DDS modules to arrive around
I've also increased the heat sink
size on the 7805 regulator feeding the CCFL inverter. The original heat sink
runs around 165 degrees F, which allows the 7805 to operate within its
ratings, but that's still hotter than my preference. The new heat sink runs
The next order of business is to revise the Assembly
Instructions and dispatch the two pre-release builds as soon as the displays
arrive. I have a good two days of work to revise the manual. And I also need to
machine several sets of support struts to go with the pre-release builds.
14 October 2006 PM
I've completed Stages 1 through 4 in about six hours. That
includes time to photograph and make notes, but since this is now the fifth Z90
I've built on a PCB, I'm further along the experience curve than most. I imagine
that most Z90 builders will run about five to six hours to complete stages 1-4.
No significant problems so far; all the parts were in the
correct bags. I did find an extra resistor that is necessary for the special
features of a prototype but omitted in the production version. I should have
deleted it from the parts list but failed to do so. Consequently, as a bonus Z90
kit builders will receive a 100 ohm, 1/4 resistor.
I'll provide a few photos of the build to date and comment
on my new Hakko 936 soldering stations first real use.
The PCB completed through Stage 4. The DDS module is an
early prototype, as the silk screened and solder masked DDS modules are still
with the assembler.
Output from the Aux Output port. It's un-terminated, so the
voltage is higher than will be delivered into a 50 ohm load. This establishes
that the DDS is functioning and that the output Gali-74 amplifier is working.
Terminal output seen at the end of Stage 2. This tests the
microcontroller and RS232 interface. Both are working.
And, yes, the firmware will ship with my callsign, but it
will not take you more than a few seconds to program in your call via the
Z90's serial data port. It's too much bookkeeping to program each PIC with a
different callsign and then keep track of them. And, it's unnecessary since
the firmware permits you to enter whatever call you wish, up to a maximum of
Hakko 936 soldering station with Macro handpiece and
soldering iron rest.
I've now used the Hakko 936 soldering station for four or
five hours. It's a better product than my Weller soldering station. The
handpieces are smaller, lighter and easier to handle. It heats up much faster,
about 45 seconds from cold start to ready to use versus about three minutes with
the Weller. Small parts do not stick to the tip, as there is no magnetic field
such as the Weller uses for temperature regulation.
I used both the Micro and Macro handpieces today. I
started out with the Micro handpiece, but soon found that it does not have
enough heat storage to handle soldering through-hole part ground pins. Although
the Z90 PCB's ground pads employ thermal relief design on both the top and
bottom, the Micro tips are too small to store enough heat to keep the solder
molten. The PCB ground plane acts as a massive heat sink and there's not enough
stored heat energy in the smaller Micro tips. I switched to the Macro handpiece
and had no problem soldering these connections. In both cases, I maintained the
adjustable temperature at 700 degrees F.
When building the surface mount sections, I switched back
to the Micro handpiece and found it pretty close to perfect. You still have to
be careful when soldering the ground connection on a surface mount part but it
isn't all that difficult after you've done the first two or three. It's a matter
of making a good thermal connection between the iron tip and the pad and part.
This, of course, is an essential part of all soldering.
If I were doing this for a living, Hakko's dual soldering
station would be the way to go. It has two independent controllers in one
enclosure�a Macro handpiece on one controller and a Micro handpiece on the
14 October 2006 AM
I'll start the experimental build later this morning,
after returning from the weekly excursion to the Burke VA farmer's market.
A few photos of the Z90 kit in its current stage:
Here is an almost complete Z90 kit. The missing components
are the assembled DDS modules and the front/rear panels and a small bag with
The cabinet is at the top, along with
the display module, installed in the support struts, along with the switch
module (upside down, as the switches are on the left when installed). The
layout includes a K2 interface kit, the K2 bandpass filter and all the Z90
Also not shown are the printed manuals.
The display and soft key switch board, looking at the side
towards the front panel. At the right of the display is the CCFL inverter
module that supplies about 600 volts to the illumination tube.
Reverse side of the display and soft key module mounted on
the support struts.
The image is of the old display unit I use for software
development, but the new RoHS compliant displays are physically identical.
13 October 2006
I've almost finished sorting and bagging parts. I found
myself short of a couple components needed for the last stage, so I bagged
everything else, and will go back and insert the short components when they
arrive mid-week. I also need to package the mechanical parts, e.g., the screws,
nuts, etc. that are not part of the standard TenTec enclosure.
Speaking of enclosures, I need to find a source of black
6-32 machine screws 1" long, fully threaded, Philips pan head, if possible. I
can find these in shorter lengths, but nothing beyond 1/2." Other types, such as
cap screws are available in black oxide finish, but not with the desired head
and/or not threaded for their full length. These are for the Z90's front panel
and I prefer a black screw if possible. If not, I have the required hardware on
hand in bright stainless steel and will supply that. If you know of a source
that will sell small quantities (200) of these, drop me a message.
Excellent news on the graphic LCD display front.
Crystalfontz shipped me two variants of their RoHS compliant displays for
approval and the first one I connected plays perfectly. No code changes, no
hardware changes. That's a major relief, as the last thing I need at this stage
of the project is to fix hardware or firmware to adjust to a new controller.
The new display model is CFAG320240C0-FMI-T and is one of
the two replacements for the CFAG320240C-FMI-T that I used during Z90
development. The new display uses an RA8835 controller chip that is RoHS
compliant and, more importantly, said to be fully compatible, pin-for-pin and
without software changes for Epson's SED1335 and S1D13305 controllers.
Crystalfontz's old "C" controller used Epson's S1D13305 controller. Apparently
Epson allowed these chips to go obsolete, rather than develop an RoHS version.
Other than the controller chip, the new display is physically and electrically
identical with the older one.
I phoned my approval and the displays will be shipped
Monday, 3rd day FedEx, so I will have them in my hands Thursday. I received the
CCFL inverters with the samples today. This leaves the front and rear panels as
the only open item of significance. I have about 60% of the enclosures and will
call TenTec next week to confirm when the last enclosures will be shipped.
I plan to grab a set of kitted parts at random from the
pile of completed kits and build a Z90 this weekend. I'll start tomorrow and
photograph the build to revise the assembly manual. I should be finished Sunday.
Of course, the cabinet will be without a front or rear panel, but otherwise it
should be complete. I'll post a selection of photos. If this goes as expected,
I'll send out two pre-release build kits Thursday for an independent test build.
I had a chance to use my new Hakko 936 soldering station
today. At Bob, K7HBG's recommendation, I also purchased the "micro" handpiece. I
like it a great deal. It's much handier than my old Weller station and it seems
to be ready to use within a minute or less of powering up. I'll take a photo or
two of the Weller and the Hakko and post them over the weekend. If you are in
the market for a new soldering station, I recommend the 936. If you can get it
with the micro handpiece, go for it. Otherwise, you will spend more for the
micro handpiece than for the complete 936 soldering station with a macro iron.
A follow-up on DigiKey. As promised, the correct
capacitors were shipped and showed up early the next day and I finished bagging
and packing that stage. A tip of the hat to DigiKey for excellent customer
12 October 2006
Another long day (about 10 hours total) sorting and
bagging parts. I've finished Stage 1 and almost finished Stage 2. (Both include
sub-stages as the builds are different for the Z90 and Z91.)
My intention was to make it easier for kit builders by
separately bagging the parts for each build stage. After thinking about it more,
this approach is likely counterproductive, or at least close to it, as the kit
can be built in about 8 or 9 hours and thus several stages are likely to be
built in any particular session. And, most kit builders wish to inventory all
the parts before starting work, hence they will open all the bags. (I do not
recommend this, but if you do this, pay very close attention to the surface
mount capacitors as they are unmarked and can be identified only via the
envelopes they are in or with a capacitance meter.) Hence, it would be little
additional work for the kit builder, for example, to receive a bag of marked
capacitors and sort them into value and then find the appropriate parts for any
particular build stage.
Packing the kit this way, instead of sorting and packaging
by build stage would save a great deal of my time, and probably be in keeping
with the way the majority of kits are packaged. For example, the Z90 must use 20
0.1uF bypass capacitors. Almost every stage uses three or four or five of these
parts. Instead of cutting 20 capacitors from the reel and putting them into the
"capacitors" bag, I cut four for this stage, three for another stage and so on.
This multiplies the number of times I have to handle parts several fold and
increases the overall error rate, as every time I count, cut and bag adds
another opportunity for a mistake.
In any event, I'm not going to change the packaging
approach on this project but probably will in the future, assuming I do
additional kits. I have a few things in mind, but can't even think about
starting a new project until this one is completed to my satisfaction. I also
have Z90 firmware improvements in mind and some modifications to the Z90 control
software that won't be started until after the current versions are released.
Plus, it will be helpful to have wider user feedback before undertaking these
firmware and software changes. One of the changes may be to de-couple the Z90
and Z91 software (presently identical) as there are some potentially worthwhile
things that I could do to the Z91 firmware that are incompatible with the LCD
display routines. This would, of course, increase the firmware maintenance and
development effort as I would have to support two parallel firmware loads.
Any comments from the kit building fraternity?
11 October 2006
I did my best to finish bagging and tagging Stage 6 today,
but my efforts were thwarted by DigiKey. Stage 6 is the crystal filter section.
I finished characterizing and packing all the crystals yesterday and today I
started on the other parts, a couple dozen capacitors and four inductors.
I had ordered all the parts a couple weeks ago and didn't
anticipate problems. However, when I opened the bag from DigiKey labeled 680 pF
I found the parts were marked "471" for 470 pF. (The bag had the correct DigiKey
part number for 680 pF printed on it.) I called DigiKey and spoke with a very
pleasant sales representative who said DigiKey would send the replacement parts
by overnight delivery and that she would call back with more information after
checking with the warehouse department. I received a call a couple hours later
and learned that 470 pF capacitors are binned next to the 680 pF parts and
apparently someone grabbed the wrong parts. Since the value of the parts was
modest, I was told to keep them.
Anyone can make a mistake and the real measure is how one
recovers from it, and I was very pleased with DigiKey.
I found 15 680 pF capacitors of the same part number left
over from my prototype builds, so I was able to finish kitting Stage 6 for 15
bags and the remainder are complete, save for the 680 pF capacitor that I will
add tomorrow when the replacements arrive.
I also had a conversation with one of Crystalfontz's
engineers about my order for the Z90's LCD displays. The model display used in
the development models recently became obsolete due to RoHS issues and is
replaced by two variants, with slightly different controller boards. Both are
supposed to be "compatible" with the older display, one more so than the other.
Crystalfontz is sending me one of each type for delivery Friday, so I should be
able to make a definitive choice on which variant I will order in quantity. Of
course, almost none of this information is explained on their web page, and in
fact, the obsolete display is still shown as an orderable part. Crystalfontz has
enough of the displays in stock to meet my order, once I decide with model to
The UPS man also delivered the 0.5" x 0.5" Delrin
stock to make the Z90's LCD support struts. I don't want to start machining
these until the front panels are here so I can double check my design against
the delivered panels.
I'll update the Swordfish DDS page later tonight.
10 October 2006
Today was "crystal filter day" at Clifton Laboratories. I
started at 0730 and finished a few minutes before 2000, a good 12 hour day with
a break for lunch and not much else. All the crystals for the 200 and 1000 Hz
filters are bagged, tagged and ready to go.
After making a couple trial measurements, I decided to
measure the crystal resonant frequency and Q using the automatic 3 dB bandwidth
measurement features of my HP87510A. If the crystal passed my minimum Q
standards, I marked it with the deviation from 8 MHz and put it into one of two
trays, each with subdivisions. One tray for ≥ 8 MHz and one for < 8 MHz. I
marked the tray divisions in 10 Hz increments and placed each crystal in the
appropriate tray bin. I was able to measure a crystal, write the deviation on it
and place it in the correct bin in about 25 seconds.
The bag of crystals waiting for measurement and sorting.
A crystal in my homebrew 12.5 ohm resistive pi test
After sorting all the crystals, I then grouped them by
frequency and tested them in either a 200 or 1000 Hz filter test fixture.
A group of crystals, marked with their frequency offset
from 8 MHz, ready to be grouped into fours to go into the test filter.
The filter test fixtures are on either side of the crystal
parameter fixture. The filter fixtures have variable trimming capacitors, but
these are not adjusted during the test.
A typical frequency response of a group of matched crystals
in the 1 KHz test filter. I found the measured bandwidth ran from about 1020 Hz
maximum to 915 Hz minimum. The bandwidth you will see in your Z90 will depend on
the tolerance of the capacitors and inductors in your particular Z90, of course,
but the prototypes I've built have all come in within this same range. The 200
Hz filters typically come in a bit narrower than the design value, usually
around 170-180 Hz.
I counted the distribution of crystals in each 10 Hz
bin, as an exercise to see if the expected Gaussian distribution would
materialize. The flanks certainly appear to follow a Gaussian distribution, but
the expected peak is not there -- in fact there's a dip, not a peak. I suppose
this could be a bi-modal distribution. Or, it's just the luck of the draw.
I allowed 30% rejects for poor Q. In fact, the rejection rate
I found today was almost exactly 10%, so I was a bit pessimistic.
For completeness, here's is a plot of one of the crystal
sets for a 200 Hz filter, measured in the filter test fixture. This is very
close to the response I've seen in the Z90 prototypes.
No Swordfish DDS update tonight. It's too late and
I'm ready to knock off for the evening.
09 October 2006 (PM)
Stage 5 is bagged, tagged and ready to go. For some reason, this was the most
difficult one to sort and bag so far. One of the cross-checks I use is to first
count out the number of components that go into a particular stage and put them
into trays. I then count out the number of bags or envelopes required for the
stage and apply the labels. Then fill the bags with the appropriate parts. At
the end of the process, the last part should go into the last bag and there will
be no parts or bags left over.
It's easy enough to make a mistake when counting out the parts, of course.
Stage 5 includes a Coilcraft WB1040 transformer and I opened the package today
and subtracted from the total the number of transformers required for Stage 5
and determined that I had 10 more than I needed, exactly as planned. I removed
10 transformers and put the rest into a tray. After bag stuffing, I found one
extra transformer in the tray. I went through all the completed bags (in clear
plastic zip-lock bags, so no need to open them up) and observed a transformer in
each bag. Counted the bags and that matched, not to mention the fact that the
only component left over from the several hundred in trays was the sole
transformer. I had my wife go through the bags and double check and she agrees
all have a transformer. Coilcraft must have shipped one extra, or my wife and I
both missed it. The real lesson, of course, is that I should not have trusted
I need a break from sorting parts, so tomorrow I'll start grading crystals.
Each Z90 or Z91 requires eight 8 MHz crystals, four for the 200 Hz filter
and four for the 1 KHz filter. Each crystal has to be graded for minimum Q and
and matched for frequency. The normal rule is to match the crystals to within
10% of the filter bandwidth, 20 Hz and 100 Hz, respectively. I'll use my
HP87510A and home made pi-style resistive crystal test fixture for the
Based on experience, I ordered about 30% extras. Extras are needed not for
frequency matching, but rather to take care of low Q rejection. In the past,
I've assigned each crystal a unique serial number and entered the Q and motional
parameters, including frequency, in an Excel spread sheet, if the crystal meets
the minimum Q standard. Then, sort for frequency and go down the list selecting
4 crystals in frequency order that are within the minimum spacing. That's a very
labor intensive process. I could automate some of it via the 87510's Instrument
Basic programming functions, or I could write a BASIC program to control the
87510A via its IEEE-488 interface. I'll give this more thought tomorrow, and see
how long it takes to do an abbreviated test via the 87510A's crystal
parameterization function. No need to record the crystal motional parameters, so
all I need to is select for Q and note the resonant frequency and write an
identifier on the crystal. Instead of a unique serial number, I could write the
offset in Hz from 8 MHz, further simplifying things.
The final test I'll make after I group and select crystals is to plug them
into a stand-alone test filter. These are duplicates of the 200 and 1000 Hz
filter circuits in the Z90, except they are connectorized and the crystals plug
into sockets. The performance in the test fixture is not necessarily equal to
that in any particular Z90 due to capacitor and inductor tolerance, strays,
socket effects and so forth. Still, it's a good final verification that the
particular crystals shipped have a good chance of working as expected when you
build your Z90.
Of course, if I were building several hundred Z90's, I would call up
International Crystal or another supplier and purchase crystals optimized for
filters, matched for frequency and all meeting my Q requirements. That's
scarcely practical at the Z90's current volume.
09 October 2006 (AM)
Bob, K7HBG, has alerted me to a couple of small discrepancies between the
notations on the Z10000 buffer amplifier silk screening and the schematics
relating to connector numbering. I've revised the schematics and updated the
Z10000 Assembly and Operating Manual and posted the revised manual at the
Documents page. The latest revision includes Bob's
dimensioned drawing showing where he mounted the SMA connector in his fully
If you have a Z10000 board and have not yet assembled it, no need for concern
as the discrepancies relate to schematic nomenclature. The schematics now
identify not just the individual input, output and power pads, but also
associates them with J90x connectors to track the printed circuit board's silk
08 October 2006 (PM)
I managed to complete the tasks I wanted to today--Stage 3
parts are bagged, tagged and ready to go. Also, Stage 4 parts are bagged, tagged
and ready to go. I also ordered the (I hope) last parts that I either missed or
failed to order earlier in sufficient quantity. By mid-week, all the parts and
packaging supplies I need to finish packing up the various stage parts bags will
Bob, K7HBG, has also supplied a dimensioned drawing
showing where he located the SMA bulkhead connector in his K2. Since his K2 has
every possible option, he had no unused holes. I will add his drawing to the
Z10000 documentation and post a revised copy later tonight or tomorrow.
A few photos of the work that went into preparing the
Stage 3 parts.
Spacer chucked into my Myford Super 7 lathe, ready to have
1/16th inch removed from its length.
I used a parting tool to reduce the spacer's length. When
you receiver your Z90 kit, you may notice some slight marking on the spacer
where it was held in the 3-jaw chuck.
After each spacer was cut to length, I ran a 4-40 tap
through it to ensure the threads were undamaged.
Holding the tap wrench perpendicular to the work is ensured by using a center
in the lathe tailstock. The center's point fits into a recess in the tap
wrench, preventing side thrust on the tap, which will, sooner or later, break
I like working with good tools, and have found that a cheap
tool is no bargain if it spoils the work. I'm far from proficient at
metalworking, but I have found a few things that help me get results far better
than when I started out building electronic equipment. With respect to tapping
holes, for example:
Don't depend on hardware store taps. For aluminum, I like
(no, make it love) Greenfield's EM-AL series taps, designed specially for
aluminum. This is a "gun flute" style tap and has a nitride surface finish.
These ain't cheap, but if you handle it right, it will last
a lifetime. Actually, it will be an inter-generational tool.
A good tap deserves a good tap holder. I like my Starrett
93A and 93B tap wrenches. The 93A is smaller and better suited for 4-40 and
The single largest cause of broken taps is side pressure.
If you do not start and maintain the tap exactly perpendicular to the work,
you will break it. Maybe not in the first hole, but before your job is done,
it will happen.
There are a variety of tools that hold the tap
perpendicular to the work. I made the one at the right as a copy of a
commercial product. It's a length of 1.25" steel bar stock that I turned down
and knurled and then drilled holes through, sized to fit common tap shank
The bottom of the fixture is counterbored to give room for
the chips thrown off during tapping to collect.
use this fixture, grab it by the knurled ring and place the counterbored side
to the work. With one hand, hold the fixture in place and with the other hand
slide the tap through the proper fixture hole and start tapping. This, of
course, assumes the work is flat.
Lastly, it's important to properly lubricate the tap. For
aluminum, I like Tap Magic Aluminum, and for other materials, regular Tap
The small plastic bottle is a needle
oilier. I found this gadget at a gun store and bought a few for general shop
use. I keep one filled with Tap Magic - Aluminum and a slight squeeze on the
bottle will deliver a small drop at the end of the long spout. Much better at
delivering precise quantities of a liquid than the normal drop-dispensing
spout that comes with the Tap Magic can.
And, of course, keep your tap clean; use a brush to
remove chips before you start tapping a hole and periodically clean it during
the tapping process.
I'll update the Swordfish DDS page later tonight.
08 October 2006 (AM)
Bob, K7HBG, has built the first Z10000-K2 buffer amplifier
"in the wild," i.e., that is not part of the test build program and has
made a few suggestions on attaching the 3-pin header socket to the underside of
the K2's Noise Blanker board. I've added Bob's recommendations to the Z10000
manual, which you may access by clicking
here or via the Documents page. Bob's
suggestions are in the section beginning on Page 31. The manual is a 3 Mb PDF
file. I also reduced the main text font size to 10 points to improve the
document's appearance and save a few trees if printed.
Today's plan includes making the 7/16" 4-40 threaded
spacers that support the DDS daughter card (part of Stage 3 construction). I
could not find a stock 7/16" spacer, so it's a matter of chucking the 1/2"
spacers into the lathe and taking off 0.062" or so with a parting tool. I'll
take a photo or two of the process and post later today.
After modifying the spacers, it's back to parts sorting
and stage assembly. Stage 3 was assembling the DDS board, but is now a matter of
adding an 8-pin header to the main PCB and plugging in the wired and tested DDS
module, so I should be able to get the Stage 3 parts bagged, tagged and ready to
go. Stage 3 parts are the header socket, the modified 7/16" spacer and two 4-40
x 1/4" stainless steel screws, so the limiting factor is modifying the spacers.
I hope to get a start, if not finish bagging and tagging Stage 4 as well.
07 October 2006 (PM)
A good part of the day was spent in sorting parts, and
assembling components into bead boxes. The parts for Stages 1 and 2, as
described in the Z90 Assembly
Manual, are in their bead boxes, ready for packaging as soon as a couple of
parts arrive. Stage 8, which is not in the on-line Assembly Manual yet, is
complete--sorted, bagged and tagged and ready to go. Stage 8 is the Z90's soft
key board. It's a rather simple stage, consisting of the PCB, six momentary
operation switches, the associated key caps, a 10-position shrouded header and a
10-position ribbon cable.
Switches before being packaged.
One switch, close up. The switches are 12 mm (about a
I'm taking photographs of each type of component and
adding it to the stage parts list. That's very likely unnecessary for the
experience level of Z90 kit builders. If you don't know what a resistor looks
like, building a Z90 is probably not the best way to start your kit
By the way, if you wish to "accessorize" your Z90, key caps
are available in a range of colors. I'm supplying basic black switch buttons,
but if you wish to order your own, white, red, green, blue and gray are
available. The correct part is a 9 x 9 mm key cap for a 12 mm switch. Omron's
part number is B32-12xx where xx are two digits identifying the color.
Mouser gets 18 cents each for them, and carries five
colors. DigiKey also gets 18 cents for a key cap and carries six colors. Of
course, if all you order from DigiKey is six key caps, their $25 minimum order
will make them a bit pricey.
I bought a dozen or so each of several colors and after
looking at them decided black was the best choice. White is not a bad
Basic black key cap that comes with the Z90.
07 October 2006 (AM)
I've posted updated operating manuals for both the
Z10000 buffer amplifier and the
Z10010 filter on
the Documents page.
I've also added a new page
Swordfish GLCD Module with source code for the library I wrote to control
the Z90's quarter-VGA display.
06 October 2006 (PM)
I've had an exchange of E-mail messages with
Emachineshop, the company I'm using
to make the front and rear panels. The good news is that they caught a mistake I
made. The front panels will be light gray (if you want to see the exact color,
http://www.emachineshop.com/finishing/powder.htm . It's "signal gray" color
ID RAL 7004.) I had earlier tried a darker color with white silk screen (and red
silk screen for the cautions) but decided the lighter gray was better.
Unfortunately, I forgot to change the white silkscreen labels to black, as white
letters against light gray is not a good combination. In any event, Emachineshop
caught this and asked if I really wanted white lettering on light gray,
suggesting black would work better. I agree and the change has been made.
So much for the good news from Emachineshop. The not so good news is that the
current delivery date is the first week in November, about three weeks behind
the original "55 days from August 23rd." The extra time means that I can finish
all the other work, including assembling one test kit myself and having
two "early assemblers" also put Z90's together. These will be without a front
and rear panel, but otherwise operational. Thus, the kits will be ready to ship
within a day or two of the panels arriving. (He said, assuming that the holes in
the panel line up with the parts on the PCB. This part, at least, I feel
reasonably confident about, as I've made paper templates from the CAD drawings
and they match perfectly with the PCB parts.)
I also have a query to Crystalfontz for an update on the LCD backorder
status, but have not yet received a reply.
I found a suitable fan at the MicroCenter and installed it this afternoon.
It's a generic single ball bearing 60 mm fan that cost $9.95, but it seems to
move enough air to keep the CPU happy, and that's the important thing.
The Geeks to Go repairman was here for a brief spell this morning, and I used
the time to discuss a few other minor issues that I've been experiencing with my
XP installation. I gave him a short look at Swordfish and he spotted an error in
the demo program up at my Swordfish DDS page. I
had started to modify the program but did not carry through and hence had
changed two variables in one place but not dimensioned them or initialized their
values the last time I saved it. I restored the program to its original form,
reassembled the test board and ran the restored code. I'll have more code
analysis later tonight.
I promised a photo of the living room and parts warehouse.
Here it is.
Fortunately, we do not use the living
room much, so it's not a great handicap to use it for temporary storage.
Speaking of storage, I highly recommend the plastic "bead organizer" boxes
made by Darice and carried at the Michaels Craft Stores in the bead department.
These have 17 storage divisions and are inexpensive. I bought five today at
$1.98 each and they are occasionally on sale at $1.50. I use them for parts
storage. Michaels carries similar storage boxes in other departments at two or
three times the price, so look carefully if you go there.
Here's a Bead Organizer box with some of the K2 bandpass
I'll update the Swordfish DDS page later tonight. I've fixed the code error
already but will also add text.
06 October 2006 (AM)
Computer problem diagnosed, if not solved. After thinking
about it more, the only explanation that made sense was the the CPU was
running much slower than it's rated speed, as the problem was independent of
Operating System. And, that the most likely explanation for that was that the
CPU cooling fan had stopped working. (Recent Intel chips slow the processor
speed way down as a power-reduction mechanism to prevent overheating.) Woke up
at 0400 thinking about it more and decided to get up and pop the cover off the
machine. Sure enough, the CPU cooling fan was not operating.
I removed the fan from the shroud and took it to the
basement workshop and applied +12V. Still would not run and rotating the blades
by hand showed some points of binding. After removing the nameplate sticker for
access to the bearings, I applied a couple drops of light oil and got it running
again. The fan is clearly on its last legs but with some luck it will last long
enough to get a replacement.
The fan is a standard part (NMB 2406GL-04W-B50) but it
does not show up at Mouser or DigiKey. A Google search is not promising either.
With some luck, COMPAQ will stock it, or the complete shroud/fan assembly. I
have a number of fans in my junkbox, removed from various computers and power
supplies but, of course, nothing remotely matching this part in size or voltage.
05 October 2006
Not a good day at all. The 1.7 GHz COMPAQ desktop machine
I use for E-mail and web browsing and as a general file and print server for the
rest of the computers in the house acted strange this morning--like the CPU was
immersed in molasses. CPU usage was pegged at 100% and moving the mouse caused
the pointer to lag by 5 seconds or more. Powering down and rebooting was even
more eventful. Booting took two hours and came up with a flag that the hardware
had been changed and Windows XP was looking to be re-validated with three days.
I spent the day trying various things, all of which were
almost impossible to accomplish as when it takes 20 minutes to launch a program
and two or three minutes to respond to a keystroke or mouse click, trouble
shooting is not easy. Windows Safe Mode has the same slowness problem.
I got out the Knoppix disk and managed to get the COMPAQ
to boot with Knoppix and it shows the same slowness. Perhaps not quite as bad as
Windows, but clearly not right. The Knoppix boot took nearly 30 minutes and
although I've only used Knoppix a handful of times, I don't remember a half-hour
At this point, I'm at a loss as to what the problem
is--possibly something BIOS related or a hardware problem seems most likely. The
files are intact and can be accessed over the local area network, albeit at a
glacially slow pace. All the Z90-related files are backed up on a separate
computer (the one I use to update this web site) so this is much more of a
problem for my normal computer usage (and my consulting activities) than it is
for progressing the Z90 project.
I finally threw my hands up and called "Geeks on Call."
Not cheap, but it's beyond my ability to diagnose and repair. I'll buy a new
computer tomorrow or Saturday, but I need to get the COMPAQ running well enough
to extract the data, or pull the two hard drives out and install them in the
replacement machine. My main backups are on a second hard drive internal to the
COMPAQ, which is probably not the optimum strategy, but I had not been happy
with the external USB drive I also have as a backup system.
As far as the Z90 project goes, I had little time to work
with it today. However, the DigiKey box arrived and that completes the major
parts order. I suspect tomorrow is going to be devoured by the COMPAQ problem as
04 October 2006
Quick update tonight as my consulting project of September
has returned for some additional work.
I've finished a few Z90 tasks before the message came in
to jump back into the consulting project for a day or so.
- I've packaged all the buffer amplifier kits into their
distribution bags, which speeds up the final shipping and, more importantly,
clears space to start on the main Z90 packaging.
- My large Mouser order arrived, which enabled me to
finish tuning and installing in their enclosures the Z10010 bandpass
filters. I was able to bring the one un-tunable filter into alignment after
reducing four of the resonating capacitors by 5%, so the filters are packed in
a box, ready to ship with the Z90/91s.
- The initial TenTec cabinet order arrived. It's two very
large boxes and one smaller box. In addition to the upper hallway being the
assembly area, our living room is now the warehouse.
- Shipped one more buffer amplifier, representing the
last of the advance shipment requests.
No time to do a Swordfish DDS update today or to take and
post any photos. Tomorrow should be back to Z90 work.
03 October 2006
Another vote for "Question Mark" has been received for the
"name this insect" photograph, so I see a consensus building.
Yesterday and today have been busy.
The final main PCBs arrived late this afternoon. I have not
yet carefully examined the boards, but there were no changes in part location
or placement from the last successful prototype, so I'm not anticipating
problems with the board.
The large rectangle is a
the bare PCB ground plane where the log amplifier shield is placed.
I've spent a good part of the day tuning and assembling
filters in their enclosures. I have 80% of the filters finished, and can wrap
up the rest as soon as I receive the bag of 1/2" x 28 hex nuts I ordered
Sunday. Each filter takes four hex nuts, as I use two as a spacer to control
the distance between the filter board and the enclosure top. I originally
thought the extra space was unnecessary and didn't have enough hex nuts on
hand. Each filter has a serial number and I'm capturing the filter
response to be provided as part of the user's documentation. So far only one
filter has failed to meet specification, although tolerance stack up means
that some filters have a cleaner passband response than others.
The filter on the right is the original prototype, done
with Manhattan-style construction using a PCB holder I made. I've discussed
prototyping techniques at my Prototyping page.
The filter on the left is one of the production units. The diagonal cuts on
the production PCB are to permit the board to fit into the Hammond 1590A
Yesterday, I received checks for two advance buffer amplifier
orders and shipped them out this morning.
Tomorrow's task is to kit up the rest of the buffer
amplifiers -- place the individually packaged bags into a larger plastic ziplock
bag comprising a complete Z10000-K2 or Z10000-U kit. This will let me clear the
decks at my kit packaging area for the avalanche of Z90 parts that will arrive
this week. If all goes according to schedule, I can start packaging the
individual Z90 build stages later this week. If the hex nuts arrive, I'll also
finish the remaining filters.
Yesterday's Z90 work started at 0700 and finished at 2300,
with a two hour break for errands and I hope to wrap up tonight a bit earlier as
I'm not used to these long hours any more.
If you have tried to access the
Swordfish page in the last
few days, you have likely experienced problems due to a nearly week-long,
system-wide failure by its web hosting service. The Swordfish site is mostly up
now, but it may be a day or two longer until the last bits are restored.
The second Swordfish news item is that its official launch
is scheduled for November 6th.
I'll add more to the Swordfish
DDS page tonight.
02 October 2006
I have two entries in 01 October's "name this insect"
I'm going with Larry on this one, mostly because the
Question Mark is found in this area according to some other Internet information
I found by searching under its Latin name, Polygonia interrogationis,
while Steve's suggestion, the Argynnis Paphia, seems to be a European
insect. Still, the silver washed fritillary has a strong resemblance to the
Question Mark. Perhaps they are related or it could be a case of parallel
evolution. In any event, it was an unusual insect to see land outside our
01 October 2006
As usual at the first of the month,
September's Updates have been moved to an archive page, reachable at the
link at the top of the page. I'll also stop placing all the text on this page in
I'm mentioned a few days ago that an important step was
verifying the DDS Daughter board was correct, and that I was not looking forward
to working with the AD9851 DDS chip, as I find it a bit on the small side for
One of the prospective Z90 purchasers, Bob, K7HBG, had
earlier asked if he could receive his DDS Daughter card as a kit, since he
enjoyed building circuits that use the AD9851. Bob recently agreed to build the
first DDS Daughter board with the new PCB layout and take burden that off my
hands. I awoke this morning to find a series of E-mails from Bob, reporting that
he had built the DDS Daughter board the previous evening and that it worked
exactly as it was supposed to. I was more than pleased to hear that. Now that
the PCB layout is validated, I plan to pack up the DDS boards and associated
parts and ship them off to the assembler in the next few days.
I've finished drilling the cases for the
auxiliary K2 IF filter, and have assembled more
filter boards. I should complete filter assembly by mid-week.
I also placed a major order with Mouser and DigiKey today,
completing the last parts buy. I'm sure I've missed some small items but those
can be obtained with a later order if necessary. The main Z90 PCBs have been
shipped and will arrive Tuesday, 03 October. I will built one and photograph it
to update the assembly manual, but I don't want to start building with the
leftover parts I've used to for the prototypes, as a few parts have changed,
mostly due to manufacturer discontinuation as RoHS parts replace those of older
design. The RoHS parts are, of course, supposed to be identical with the ones
they replace, but I still feel safer waiting until I can construct a test
assembly with the identical parts that I will ship. And, of course, the front
and rear panels are not yet shipped, the LCD modules are backordered until
mid-October and about half the enclosure order from TenTec will ship this week,
with the rest backordered until later in October. So, it still looks like the
second half of October for Z90 and Z91 shipping. It's possible that the Z91's
could go before the Z90's if the LCD modules are late.
I have a couple photographs of something totally unrelated
to the Z90, or, for that matter, radio at all.
I have no idea what it is, but whatever it is, it landed on
the railing along the back door. For a scale reference, the vertical
square post is 2" x 2". If you know what it is, drop me an E-mail. It resembles
an autumn leaf when its wings are folded. It very late in the season to see a
butterfly (or whatever this thing is) in Northern Virginia, as the flowering
plants have long since dropped their petals.
I'll also add a new
installment to the Swordfish DDS page tonight.