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Software Updates
Softrock Lite 6.2
Adventures in Electronics and Radio
Elecraft K2 and K3 Transceivers



The Z10000B Buffer Amplifier is available for purchase.

NOTE - The Z10000 is replaced by the Z10000B as of November 2009. The design and performance specifications are identical with the original Z10000. There is no price change with the "B" version. The main differences are:
  • Changed to a surface mount voltage regulator
  • Slightly smaller printed circuit board
  • Rearranged parts layout for easier building
  • Bottom board surface now has silk screening
  • Component ID now starts with R1, C1, etc.

Since the performance specifications are not changed, I have not revised references to the Z10000 to add the "B" suffix on this page and elsewhere on this web site. Hence, unless otherwise specifically mentioned, information on the Z10000 applies equally to the "B."

Introduction to Z10000

The primary purpose of the Z10000 is to provide a method of extracting an isolated and buffered sample of the intermediate frequency (IF) signal out of a receiver or transceiver. The IF sample can then be fed into a spectrum analyzer or panadapter. The Z10000 is, however, also usable as a general purpose small signal amplifier with excellent reverse isolation and usable gain well above 100 MHz.

The Z10000 was developed to integrate into an Elecraft K2 transceiver and provide a buffered IF signal sample at 4.9 MHz.

One new use of the Z10000 is to provide additional reverse isolation between an Elecraft K3's IF output port and a Softrock receiver used as a panadapter. The extra isolation is necessary because the Softrock has a rather strong leakage signal (around -40 dBm) out of its antenna input port. As a matter of good engineering practice, it's desirable to keep strong signals like this out of the  receiver's IF chain. Although the K3's IF port is buffered, the reverse isolation of the internal source follower appears to be only around 20 dB. The Z10000 has a reverse isolation exceeding 70 dB.

How to Purchase the Necessary Softrock Kit

I've been asked how one acquires a Softrock Lite (now the Softrock Lite II) kit to be used as a panadapter for the K2 or K3. Tony Parks, KB9YIG, "Mr. Softrock" replied to my query as follows:

Hi Jack,
Yes, I can supply both of the IF kits you list below at a price of $12 per kit.  The K2 IF kit has a 4.898 MHz center frequency and the K3 kit has a 8.191 MHz center frequency.

I suggest you first visit Tony's web site which has the most recent availability and pricing data. . 

The offset from the nominal IF center frequencies of 4915 KHz (K2) and 8215 KHz (K3) is helpful as it places any residual local oscillator leakage outside the receiver's crystal filter.

I've also written extensively about how the Softrock Lite 6.2 can be used as a panadapter with the K2 at my Using Softrock as a Panadapter for the K2 page.

Z10010 Bandpass Filter

If additional out-of-band isolation is desired, Clifton Laboratories also offers the Z10010 coupled resonator bandpass filter. Stock designs are available for the K2 (4915 KHz, 200 KHz bandwidth) and the K3 (8215 KHz). Custom designs for other frequencies are possible. More information on the Z10010 can be found by clicking here or on the Z10010 link in the navigation bar at the left of the screen. These filters are normally supplied assembled and swept-aligned with a plot of the filter performance.

The options and pricing for the Z10000B are:

  • Base kit�printed circuit board, all electronic parts to build the broadband (universal) version of the PCB, including a complete set of gain-setting resistors. Price is $24.95.
  • K2 filter parts�Parts necessary to provide a bandpass filter shaped response, centered around 4.9 MHz for the K2's IF. The filter parts are installed on the printed  circuit board. $9.95. This option is desirable if you intend to use the Z10000 with an Elecraft K2.
  • Internal Installation parts�Parts necessary if you wish to install the Z10000 inside a receiver. Although intended for the K2, they can be adapted to work in most receivers. These include a pre-assembled SMA female bulkhead connector with 2 ft length of RG178 miniature Teflon coaxial cable, fish paper, stand-off and wire. Price is $14.95.
  • All inclusive kit�All three above. Price is $44.95.
  • Header pin connectors�In the most common installation mode, the Z10000 is hard wired into the circuit. However, the input, output and power pads are compatible with standard 2-pin, 0.1" spaced pin headers. A set of three 2-pin header pairs (three pin plugs and three sockets) is $2.50 if purchased at the same time as the Z10000. If the pin connector option is purchased at the same as as an assembled Z10000, there is no additional charge for installing the pin connectors.
  • TenTec Orion Installation Parts�I've developed an accessory installation parts set for anyone installing a Z10000 inside a TenTec Orion, following VE7TK's documentation, The installation part set consists of 2 feet (0.6m) of RG-178 miniature Teflon coaxial cable, and a 4-40x½" threaded M-F standoff, with lockwashers, a 4-40 small pattern stainless steel hex nut and a 4-40 stainless steel machine screw. The Orion Installation Parts set is $3.00 if purchased at the same time as the Z10000.
  • Jumper cable, male SMA to male BNC, approx. 3 ft (90 cm) length, RG-174 cable. $9.95.
  • Virginia Sales Tax�If your Z10000 is to be delivered within the Commonwealth of Virginia, don't forget to include 5% sales tax.
  • Assembly of Z10000. For an assembled and tested Z10000, add $12.50. The user is responsible for installing the Z10000. Please specify the desired gain setting when placing your order for an assembled Z10000. Assembled Z10000's will be shipped with a set of gain-setting resistors, should you wish to vary the gain later. Assembly does not include attaching cables to the board; it is the purchaser's  responsibility to attach the board to the coaxial cables and power wiring.

    Assembled Z10000 in enclosure. I can also provide a Z10000 assembled in a 2 inch x 2 inch die-cast enclosure, as illustrated below. The enclosure option for an assembled Z10000 is $25.00 and may add a few days to delivery. If you wish to build the Z10000 as a kit, I can also provide the enclosure, drilled and with connectors, etc. for an additional $22.50. Please contact me for RF and power connection options before ordering the enclosure.
  • Assembly in Europe. For Clifton Laboratories customers in the UK and other European countries, Dave, G3TJP, is willing to assemble kits for purchasers in exchange for a contribution to a suitable charity. Dave may be reached at
Optional enclosure for Z10000 amplifier

These prices include shipping via first class mail within the US. International shipping is available at extra charge. Based on the size and weight of the kit, international first class air-mail shipping should be around US$ 4.00 or less to most European countries. International purchasers should contact me via E-mail for an exact price quotation. Payment may be made by PayPal or check.

To order:
To order by PayPal, send the correct funds to Checks should be payable to Clifton Laboratories and sent to the address at the top of this page.

Please contact me to obtain a quotation on international shipping if you are outside the USA. International customers paying with an International Money Order will have a US$ 5.00 surcharge, as my bank charges $ 5.00 to deposit an international money order. PayPal is much more efficient and I encourage international customers to use it instead.

The price does not include a printed manual. You are responsible for downloading the assembly manual from this site.

There are three Z10000B manuals:

  • Assembly and operation of the "U" or universal version. Click here
  • Assembly and operation of the "K2" version. Click here
  • Installing the Z10000B-K2 inside an Elecraft K2 transceiver. Click here.

In order to make  the "B" version manuals shorter, I've deleted material covering surface mount construction techniques, K2 BFO leakage, gain versus frequency for varying gain settings and installation in other than K2 transceivers amongst other things. This material continues to apply to the B version and may be found by reading the original Z10000 manual, available by clicking here or via my Documents page.

These documents are also available at my Documents page. Installing the Z10000B in an FT-920 is discussed here.

If you have an IF output port on your receiver/transceiver and just want a Z10000 to provide isolation between your Softrock or other panadapter and the receiver, all you need is the base kit. The Z10000 PCB might be installed in the same enclosure as your Softrock.

If you have an Elecraft K2, then you likely will find the all inclusive kit  the best option.

If you have a receiver or transceiver other than a K2, but without an IF output port, then you will likely wish to purchase the base kit and  the internal installation parts. You would not need, nor find useful, the K2 filter parts.

One caveat must be made now�my measurements on a Softrock 6.2 Lite receiver show local oscillator leakage (crystal frequency / 4) at about -40 dBm, an extremely strong signal level. (Click here for details.) The Z10000 has a reverse gain (isolation) around -70 dB, depending on frequency. (Details are in the Z10000 documentation, available by clicking here.) Thus, the Z10000 will reduce the Softrock's leakage level to around -100 to -110 dBm, assuming proper attention is paid to shielding and bypassing. However, a -110 dBm signal is still quite audible when injected into a receiver's IF stage. Hence, either additional isolation will be necessary, or you will wish to intentionally shift the Softrock's center frequency to one side or the other of your receiver's IF bandpass filter. The Softrock kits supplied by Tony Parks have such an offset.

Some transceivers, such as Kenwood's TS940, employ a separate panadapter signal path and hence are less subject to this leakage problem than others. In the Elecraft K2, for example, you will wish to offset the Softrock several KHz from the nominal center.

Z10000 Specifications

Z10000 Specifications


Common to Z10000-K2 and Z10000-U

Physical size

Approx 1.4� (35 mm) x 1.25� (32 mm). Height approx 0.2� (5 mm) plus clearance for wiring.

Mounting hole: clearance for 4-40 machine screw.

Power Requirements

+12V at approx 20 mA.  On board regulator permits operation with 30V maximum supply voltage.


None. Direct wire (coaxial cable) connection via solder pads.


User settable via programming resistor. Different maximum and minimum for �K2 and �U models.

Output Impedance

50 ohms; short circuit protected.

Active Devices

78L09 voltage regulator

AD8007 amplifier

Reverse Isolation

Typically 90 dB at 4.915 MHz; depends on cable routing as stray coupling becomes important at this level of isolation. Less isolation at higher frequencies. See Section 1.3.3.

Harmonic Distortion (2nd and 3rd harmonic)

Typically 80 dB below carrier; depends on gain setting and input level

3rd order intermodulation distortion

For two equal level signals 9900 & 10100 KHz at -10 dBm input each, with 50 ohm through on Z10000 input, Z10000 set for +10 dB net gain, output IP3 is approximately +33 dBm.

Input Signal Level

DC not to exceed 25 volts; AC input level depends on gain setting; typically used with a less than 100 mV PP input.





Flat within ±1 dB over 200 KHz range centered on 4915 KHz. Rolled off above 6 MHz and below 4 MHz.

Depends on gain. If set for +6 dB net gain, usable bandwidth > 100 MHz. (See typical performance plot) Low frequency response extends to below 50 KHz.

Input Impedance

Depends on bias isolation resistor setting; used to provide extra roll off and loss; recommended values range from 1 K to 4.7K ohm

Depends on frequency and attachment technique. Greater than 1.5 K ohm to 10 MHz, (See typical performance plot)


Depends on R905 & R907 values. Typical maximum gain at 4915 KHz is +9 dB, typical minimum gain is -18 dB

Depends on R907 value. Typical maximum gain at 5 MHz is +14 dB, typical minimum gain is -4 dB


Photos of Assembled Z10000B
Z10000B top

Bottom view of the Z10000B-U version. Frequency shaping filter components are installed on the bottom surface in the Z10000B-K2 option.

Forward Gain and Reverse Isolation Data

I assembled the Z10000 pictured above for a nominal 6.7 dB gain, which is quite close to that measured over the range 1 - 100 MHz. The slight rise as 100 MHz approaches is due to a peaked high end frequency response. The nominal 6.7 dB gain is within 0.1 dB of the measured value at 8 MHz. The  data is taken with an HP8752B VNA, log frequency axis.

The reverse isolation measures 92 dB at 8.215 MHz, about 20 dB better than the figure I quote, which was based on a connectorized prototype version of the first PCB run nearly a year and a half ago.

I re-ran the forward and  reverse gain of the prototype Z10000 from which I based the 70 dB isolation value. The forward gain (with a 50 ohm through termination on the input) closely matches the above data. It's actually about 20 dB better, measuring -115 dB isolation.

At this point, I started to question my test equipment and/or sanity. As a check, I ran the reverse isolation with power disconnected to the connectorized amplifier.

Compare this data with my data from a year and a half ago for the same device.

March 2008 measurement - no power applied

September 2006 measurement

Interesting, no? The data matches quite well, with about a 5 dB offset. I now think that my September 2006 data was taken with the power inadvertently removed from the amplifier. 

To verify this, I ran both amplifiers in forward and  reverse with a completely different test setup, an HP8640B signal generator and an HP8557A spectrum analyzer. The data matches the VNA plots in both directions. Hence, I conclude that the Z10000 is providing considerably greater isolation than I thought.

Why would the amplifier measure much greater isolation when powered up than unpowered? I assume  this is because in the unpowered state, all PN junctions within the AD8007 chip are un-biased and hence are, for low signal levels, moderate value resistors, including parasitic or sneak path junctions. When powered up, many of  the sneak path  junctions are reverse biased and hence high impedance, which will greatly reduce unwanted signal coupling within the AD8007.

I'm still cautious about revising the Z10000's specifications to show the new reverse isolation figure without some independent verification.

Update on Isolation

I've received confirmation from Bob Friess, N6CM, that the Z10000's isolation is well above my earlier quoted 70 dB:

Hi Jack,

The amplifier seems to work very well.  I am limited here in the desert by an old analog network analyzer, but S12 is something greater than 80 dB.


S12 is, of course, reverse isolation, signal applied to port 2 (output), measured at port 1 (input).

Hence, the correct isolation is in 80-90 dB range, as it's now clear my lower quoted figure must have been made with the power inadvertently disconnected.

How much isolation does the Z10000-K2 provide when installed in a K2?

To determine how much isolation a Z10000-K2 buffer amplifier provides, I attached an HP8657A signal generator to my K2's IF sample output port. With the 8657A set to approximately 4915 KHz and the K2 in CW mode, I increased the generator's level until I could hear a weak CW beat tone. At this point, the signal generator's output was -10 dBm.

This is quite  remarkable isolation, and at this level of suppression details such as coaxial cable routing, etc. become important. I don't, therefore, warranty that you will see the same level of isolation when installed in your K2, but rather regard this value as typical.

3rd Order Intermodulation Performance

I set a prototype Z10000 buffer amplifier for +9.7 dB gain and  ran a 3rd order intermodulation test. The results confirm measurements I made when developing the Z10000; it's a high performance amplifier in many respects.

The test setup I used is below. The hybrid combiner is the one described at my 6 dB hybrid combiner page, Design 1. The low pass filters are also described at that page.

The AD8007 is set for high Z input, so I use a Pasternak Electronics 50 ohm through to properly terminate the hybrid combiner output.

The prototype Z10000 buffer amplifier I used for these tests is essentially identical with the production units, but is without an on-board voltage regulator and has BNC connectors for easy connection to test equipment. The first series of tests is run with +12V to the AD8007 amplifier. A later test shows that at +9V, performance is essentially unchanged. Hence, this data directly applies to the production Z10000 amplifiers.

The test signal out of the combiner is shown below. The level is set at -9.7 dbm so that the Z10000's output will be 0 dBm. There's just the slightest trace of a 3rd order product visible in the noise. or, then again I may be seeing  things that are not really there.

The image below is the Z10000's output at 0 dBm into the spectrum analyzer - but is the intermodulation from the Z10000 or  the Advantest R3463 spectrum analyzer?

We may easily answer  this question. I've placed a marker on the 9700 KHz 3rd order intermodulation product. Its level is -62.5 dBm. If we insert an external 3 dB attenuator between the Z10000's output and  the R3463's input, all signals generated by the Z10000 will drop 3 dB; the two test tones and  the two intermodulation products. If, however, the 3rd order intermodulation products are generated in the R3463 spectrum analyzer, the external 3 dB pad will drop the two tones 3 dB, but any 3rd order intermodulation products will drop 9 dB.


As can be seen below, the two test signals drop 3 dB, but the 3rd order intermodulation products drop considerably more. The 9700 KHz product went from -62.5 dBm to -71.0 dBm, an 8.5 dB reduction, pretty close to our predicted 9 dB change for 3rd order IMD internal to the R3463. We therefore may safely conclude that the products seen are generated inside the Advantest R3463 spectrum analyzer, not in the Z10000.

All spectrum analyzers will have internally generated intermodulation products if overdriven; that's why intelligent use of  the analyzer's built-in attenuator is necessary. Switching in an extra 10 dB attenuation will drop the 3rd order products 30 dB, if the products are spectrum analyzer generated. Hence, we will take our Z10000 performance measurements with a total of 33 dB input attenuation; 30 dB in the R3463's internal switchable attenuators and 3 dB in the outboard attenuator.

The image below shows the Z10000's output with an extra 10 dB attenuation switched into the R3463's input and the external 3 db attenuator in place. The Z10000's output is 0 dBm and the 3rd order intermodulation product at 9700 KHz is -73 dB with respect to the single  tone level.

The Z10000's 3rd order intercept is thus 0 dBm + 73dB/2 = +36.5 dBm.

Reducing the supply voltage to +9V makes a nearly imperceptible  change in the intermodulation product level.

Z10000 in an Enclosure

To use as general purpose laboratory amplifiers, I constructed two Z10000 boards. I made several changes to these boards to enhance their use as lab instruments:

  • Replaced 78L09 voltage regulator with 78L12 to increase the AD8007's supply voltage to its maximum rated value. Nominal supply voltage is 15-18 volts at the regulator input.
  • Replaced all 0.22µF 1206 capacitors with 1µ0 1206 parts to improve low frequency response.
  • Added 49.9Ω 1206 resistor across the input to make  the amplifier a 50 ohm input device.
  • DC supply is fed via a 0.01µF feedthrough capacitor and a RF choke wound on a Fair-Rite Type 43 material toroid.
DC Power and Output end of the amplifier
49R9 input resistor added. The resistors are fragile and crack easily, so add the resistor after the input wire is in place.
One of two completed amplifier. The ground lug is secured under one of the box mounting screws.

If you wish to duplicate my arrangement, use the following dimensions. Two cautions are appropriate:
  1. The amplifier must be centered along the lid as the enclosure opening has only a slight clearance on the narrow dimension. The dimensioned drawing shows the distance on the Y axis as 0.47 inches. It's actually 0.462 inches on  the two units I built.
  2. The dimensions are keyed to looking at the lid from the bottom, i.e., as shown in the two photos above.


As the sweep data shows, the 3 dB bandwidth is 3 KHz to 175 MHz. Both amplifiers have essentially identical performance.

I constructed these with 95.3Ω gain setting resistors. The  theoretical gain is thus 20Log((499+95.3)/95.3) = 15.90 dB. Since the amplifier has a series 49.9Ω series resistor to allow it to safely drive capacitive loads, the realizable gain into a 50 ohm load is 6 db less, or 9.90 dB.  The measured gain at 5 MHz is 9.76 dB, 0.14 dB less than theoretical.

The horizontal axis (frequency) in the plots below is logarithmic.



Installing a Z10000 in specific radios

I've added separate web pages showing how a Z10000 has been installed in specific transceivers. Click on the name for the link.

Rick, VE7TK, has written a tutorial on using a Z10000-U buffer amplifier to extract a wideband 9 MHz IF sample from a Ten-Tec Orion (model 565) as well as the Orion II (model 566), available from Rick's web site at (contents are subject to change, as Rick notes.)