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December 2008 Archive


31 December 2008

Thanks to Dave, G3TJP, for letting me know that my new page Inductor Choice for Band Reject Filter was mangled.

I use Microsoft's Front Page to prepare and publish my web site and for a reason that remains unknown to me, it decided to swallow several paragraphs of text. I've rescued the page, which required copying the mangled material into Notepad and then pasting it back into Front Page, followed by reformatting to the way it should have been, upon which it became visible. Of course, the original test displayed perfectly in Front Page's "design" mode which leads me to suspect a bug in the way Front Page creates HTML from the design mode entries.

I also can't say that I care much for how my equations are rendered in Firefox. I create them in Microsoft  Word with Equation Editor and then copy/paste into Front Page. Instead of being rendered in nice fonts, they are converted into bit-mapped images with the usual jagged blocky appearance. Internet Explorer, in contrast, has fewer jaggies and a less blocky appearance.  I'm sure there's a way to do all of this more elegantly, but there's a limit on my time and interest in learning yet another piece of software.

I understand that Microsoft has dropped Front Page and is pushing another HTML editor, so perhaps my problems are not unique.


30 December 2008

As the year 2008 draws to a close, I've been working more on several new kits. One is an AM broadcast band rejection filter. I've added a new page discussing (at great length) why I picked the particular inductor cores that I did for the filter. You may read the page by clicking here or via the page links at the left.

If you are interested in purchasing one of these filters, drop me an E-mail at I'll have more details in the spring as the other kits are finalized. At the moment, I believe the AM band reject filter kit will require the  builder to have a method of accurately measuring inductance, such as a Q-meter or AADE's LC meter. I plan on providing a set of wound and measured inductors as an option for kit  builders without this test gear, as well as assembled and swept filters.

The filters will include a painted die-cast enclosure, which is not shown in at the linked page. I'll have full details including price and availability in the next month or two.


21 December 2008

I've added a new page K3 Power Setting Accuracy with the results of measurements I've made of my Elecraft K3's output power versus commanded power level. Updating the K3's firmware to the most recent version and recalibrating  the power associated parameters improved the agreement between commanded and measured power levels, but there remains a consistent error trend associated with power level and frequency.


16 December 2008

JFETs are notorious for having wide parameter spreads. It's not uncommon to see a 3:1 or even 5:1 ratio between the maximum and minimum parameter values.  I've spent the day measuring a collection of JFETs to see how much variation in transfer characteristics might be found. The details are at JFET Variation.


08 December 2008

I've added a new page WWV Short Term Jitter looking at changes in time of arrival of WWV at 10 and 5 MHz. Why look at this? It can tell us a bit about how signals arrive in terms of how many reflection points exist and also how much technology has changed since the 1959 HP Journal suggested the method I implemented. I've also used the measured data to calculate the distance between Ft. Collins CO and Clifton VA.


05 December 2008

I've corrected and expanded the discussion in using LTspice to simulate non-linear capacitance at Capacitor Voltage Change..


05 December 2008

I've added a significant section to my earlier page on capacitance change with voltage Capacitor Voltage Change to provide distortion data for Y5U ceramic, ceramic monokap and polyester parts (0.1uF) with and without DC bias. The new data and discussion is at the bottom of the page.


04 December 2008

I have an answer to the E-mail problem covered in yesterday's comments�when updating my storage space quota, XO turned off the "forward to main account" option for un-identified E-mail messages. I've now re-enabled the function. This option is not located in the normal E-mail setup and management page in XO's account access, explaining why I couldn't find the option selection yesterday. A helpful E-mail from XO support pointed me in the correct direction.

Since re-enabling the option yesterday evening, about 14 hours ago, I've received 114 junk messages sent mostly to random names at There's a delicate balance between the annoyance at having to scan all these junk messages after they are filtered versus missing a legitimate message mis-directed due to an error by the sender.


03 December 2008

This web site and my cliftonlaboratories E-mail are hosted by XO Communications and I've never had a problem with either the site pages or E-mail until a couple days ago. When setting up the Clifton Laboratories account, I had opted for all E-mail messages, regardless of the name, to be forwarded to me. This meant that messages that, for example, omitted the "dot" and were sent to jacksmith instead of jack.smith made it through. This also meant that hundreds of junk messages a day addressed to random names, such as accounting or accountspayable at clifton laboratories also made it through. However, Thunderbird, the E-mail client I use (and recommend), did a pretty good job at sorting through these messages and filtering the crud into a separate folder that I could quickly scan for legitimate messages.

However, beginning around the first of December, I noticed a major drop in these unwanted messages going to cliftonlaboratories addresses. I didn't think too much of this until I realized today that receiving almost no junk messages after typically seeing 100-200 per day meant that something changed.

It seems that XO changed my account to block all messages except those addressed to names that I have specifically identified as valid. I've asked XO whether this is a new system-wide policy and if not how I might return to receiving all messages, regardless of name, but have not yet  received a response.

This is a long way of saying that anyone who has sent a message to me in the last three or four days and failed to receive an answer should check the address and re-send it to jack.smith.

I've also had XO update my account to increase the storage from 250 MB to 2 GB. This will allow me to post higher resolution images and the like. (Believe it or not, I had used nearly 90% of the 250 MB limit at this site as of the end of November.)

I hope to have a new page with updated non-linear capacitance measurements completed tonight or tomorrow.


03 December 2008

As usual, I've moved the November 2008 Updates page to archives, reachable by clicking here or via the table at the top of this page.