Category Archives: Uncategorized

New order of PCB’s for the DG5 emulator has been placed

Based on the feedback and e-mails requesting a DG5 emulator board, I placed an order for another run of PC boards – should ship on the 11th from the PCB house here in the US. I’ll post here when the new boards arrive and are ready for shipment, and I’ll do my best to individually e-mail those who have written me over the past few months.

Thanks for your continued interest!


DG5 boards SOLD OUT.

I am out of the DG5 emulator boards. Given that the last few boards came in slowly, I am not planning on another board production run at this point. If enough folks want one (make a post below), I’ll look into another run of boards. Thanks to all who have purchased, and I hope you’re enjoying your Arduino AD5 emulator!

7/31/15 – I have received a lot of interest over the past few months, so I have put in a request for pricing on another order of boards – will let folks now if I pull the trigger! Thanks for your patience!


DG5 Emulator boards still available as of 2/8/15

DG5 Emulator boards are still available, 10 left as of this morning (2/8/15). Details on the project, with a link for ordering a board can be found here.

It sometimes takes me a day or two to respond to e-mails or posts made as I have a new job that’s keeping me busy. I took a position back in November managing a public safety radio system, an 800Mhz, P25 based trunked system with about 133 repeaters across 13 sites! There’s a lot going on, so I haven’t had a whole lot of time to play around with the TS-520S and the DG-5 emulator, however, one of the points to the open source movement is to allow for others to take a project and run with it. I had some code on the running on the Arduino late last year along with a AD9850 DDS board that added a DDS VFO to the 520S – there’s lots that could be done if someone want’s to put in the time!


UPDATE – as of 2/13 I only have 4 boards left. If there is continued interest once these are gone, I’ll make a 3rd run of them.

UPDATE – as of 2/15 I only have 2 boards left.

Digital readout for the original TS-520 by Mark Mohrmann, WA2FXM

Mark has written up a terrific document detailing how he added the Digital Display to his non “S”  TS-520.  There was a kit for the TS-520 back in the day to add the CAR/VFO/HET signal outputs, the TS-520S came with this option built in. Mark details how he built the interface, including the buffer amp necessary for the HET signal.  Thanks Mark!

New boards should be here any day, build pics from Mike, KD2DYY

To all those who have e-mailed me about boards, I should have the new run here soon, maybe even today! (UPDATE – FedEx says Tuesday, 12/2)  I’ll send each who requested an e-mail when I have them in hand.

Mike, KD2DYY sent me some pics of his build – nice work!  He did have some issues with the version of code, and the cable sets he was using – make sure you’re using the latest code (V1.5) that can be found on the build page:

Also, do make sure that the RCA cables you are using are good – I am using a set of cables that were from an old AV piece of gear. It’s original use was to carry Left and Right audio, and composite video, and it seems to work fine in this application.  Mike had to try 3 different cable sets before he got it working.  Here are some pics of his build:




Nice work, Mike!


DG5 Emulator Boards stock status

UPDATE 11/17/14 – new run of boards have been ordered today from AccuTrace, with a scheduled ship date (to me) of 11/24/14.  Rather than accepting orders right now, I’ll ship first come, first served to those who express interest via a post here.  No commitment, but if your interested please post a reply to this post (below) and I’ll reach out to you first.  After those orders have been fulfilled, I’ll reactivate the “buy now” link on the project page.  Thanks!

UPDATE – SOLD OUT as of 11/13/14. Please post here if you’re interested in a board – I’ll make more if folks want them!

I only have one more board (my original order was for 20), when that one is sold, the PayPal button should direct folks who want to buy a board here.  If you’re interested in a PCB for this project, please leave me a note – if there’s enough interest I’ll have another run of boards made an e-mail you when they come in.

Steve build video

Todd over at has posted a new video, part 5 in his Arduino Frequency Display For Kenwood TS-520S HF Ham Radio series:

In the video, he solders up the project, mounts it in a chassis, and tests it out.  You can also see the previous 4 parts on how he came up with the design on his website.  Nice to see it built and working out side of my bench!

They did have an issue with the frequency appearing to be slightly off, that might have been the version of code he was running – the gate time seems to work best (and be most accurate) at 125mS, the original code was using 100mS.  Another issue that I have run into is that the later Arduino’s (like the UNO) do NOT use a crystal for the clock – they use a ceramic resonator.  Fine if you want to blink some LED’s, not so good if you want to measure a frequency.  Todd and I both used Arduino  Duemilanove’s – they can still be purchased at places like

This is all open source – you can download the project, the BOM and the code from this page.

Great to see the end product. Let me know if you build one!


DG5 mounted and ready to go!

I ordered up a 2″x4″x 5″ extruded aluminum chassis off of eBay, and mounted the DG5 and the LCD display.



It’s looks good, and the metal shielding eliminated some slight RFI from the board.  There are multiple, HF signals on the board being amplified and switched – a metal chassis is recommended!


Looks good on top of the TS-520S!

Strange dreams about VFO drift.

I have strange dreams.  I often awake with new ideas on something that I am working on, which really isn’t all that strange, but when I try to explain my dreams to my wife, well…. they’re strange.

Yesterday morning I woke up thinking about other things I could do with the DG5 shield, and one of the things I dreamed about was making VFO drift measurements.  Using the DG5 emulator and the USB communications with the computer, I could log the calculated VFO frequency over time, and see how my VFO drifted during warmup.  This was pretty straight forward, instead of scanning thru three frequencies to measure, I just locked the board to the VFO and increased the gate time to 1 second, and took a measurement every 6 seconds.  I printed these results to the serial port and captured them with my computer.

Now, there’s another source of drift in this setup, and that’s the crystal oscillator on the Arduino itself.  The crystal’s I have used for other ATMega328 based project boards are rated at 20ppm at 16Mhz – the clock frequency the Arduino uses. 20ppm works out to be +/- 320 Hz = quite a bit of potential measurement error!  But crystals don’t usually drift all over the place in short periods of time, with relativity stable temperatures.  I had the Arduino and the shield powered up overnight with the TS-520S off, so I figured it would be pretty stable for a measurement of the TS-520S VFO drift during warm-up.


Here’s the drift plot over about 3 hours of warmup.  I suspect most of the calculated drift is the TS-520S VFO, and not the Arduino. But we can actually eliminate the Arduino’s error using one of the DG5’s other inputs.

By using an external frequency reference, we can eliminate the Arduino as a source of the error.  The DG5 emulater can select from 3 inputs for measuring (2 direct, 1 prescaled by a divide by 8 counter), so I used my HP 8924C as an external frequency reference. It uses an OCXO (Oven Controlled Crystal Oscillator) for it’s frequency source, which is much better than the $0.39 Arduino crystal. I don’t have the spec’s in front of me, but if I remember correctly, it’s something like 0.05 ppm or better.  I have used it to obtain sub 1 Hz measurements in the ARRL Frequency Measurement Test (, so it’s pretty good at these frequencies.

This time I had the program select the VFO input, make a measurement, then select the external frequency reference (which was set to 5.000000 Mhz) , and make another measurement, Since we know the input frequency is 5.000000 Mhz we can calculate the error, then apply that error to the measured VFO frequency.  The data of the Arduino looks like this:


That’s the fist minute or so of data out of the Arduino.  The columns are VFO (the raw measured frequency), the Ref (the 5 Mhz reference frequency as measured by the Arduino), The calculated error (REF – 5,000,000), the corrected VFO frequency (Measured VFO + ERROR), and lastly the millis() function out of the Arduino which gives us the Millis counter value – how many milliseconds we’ve been running.

Put this in to Excel, and we get this:


Here’s the calculated error in Hz over about 7 1/2 hours (I left it running overnight).  Looks like the Arduino is -59.512 Hz low on average, but drifted only about 5Hz during the test.  Not bad, and perhaps I should add a frequency error compensation factor in the DG5 code.

Here’s the corrected VFO drift over 7 1/2 hours:



Even after running all day, the TS-520S’s VFO continues to drift appreciably – about 40Hz over this time frame.  No big deal – it’s amazingly stable for the technology – but it’s sure nice to be able to characterize it!

Points learned:

  • It looks like the Arduino frequency stability is about 10x better than the TS-520’s VFO in this setup, which is good since we’re looking to the Arduino to measure the VFO.
  • I have only measured the VFO so far, I’ll probably do a similar exercise with the BFO (which mixes with the VFO to obtain the IF frequency) and the Hetrodyne oscillator (HET) to see how stable they are.

The DG5 shield can be a useful tool as well as a frequency display!