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EU1KY AA Firmware stabilization version update (V0.4) and mores about v0.4

EU1KY AA Firmware stabilization version update (V0.4) and mores about v0.4

V0.4 has been changed to the stable version without changing the version number.

I and testers tested for about a week and did not have any problems, so I added V0.4 to the stable version list.

1.Download stabilization version
Click below for more information on the stabilization version.

Version 0.4

How to create AA
(Information is constantly being updated)

2.Additions about digital mode with Antenna Analyzer
From V0.4, WSPR, FT8 and JT65 transmission functions have been added.

There were reports that the antenna analyzer alone succeeded in the WSPR beacon without any hardware modifications or additional circuitry.

For low power WSPR, please refer to the link below.

If your antenna performance is OK, connect the antenna connector to S2 of the Antenna Analyzer and try to transmit the WSPR.

2.1 If you want to increase the output, see below.
  If your antenna performance is not as good as me, you can use WSPR by increasing the output as shown below.

  You may be able to increase the output with just a few parts.

 The simpler method is to use the following parts.

  It is an LNA that can be purchased for about $ 6 to $ 8 on eBay or AliExpress.

 When I tested it, the output was about 300mW. I used this and a car whip antenna and got a pretty long distance WSPR report.
It is very weak, but you can add LPF if you need it.

3.Things working on these days
Various experiments related to VNA (S2 -> S1)

3.1 I used a short coaxial cable when testing the S21-Gain.
  It is possible to measure about -40 ~ -50dB up to about ~ 150Mhz.

3.2. If a diode is added as shown below, connect a -10dB attenuator between S2 and S1.

If you do not use a diode like me, you do not need to add anything.

 3.3 There was an experiment that adjusted impedance using BGA616
 (thanks dummy load). The tester switched the impedance by changing the switch.
He says there is no need to this mod.

3.4 Experiment S21-Gain with controllable atteunator
I and DH1AKF talked about controllable attenuators a few weeks ago.

Below is a photograph of the experiment sent to me by DH1AKF.

Below is another form of PE4302 that arrived to me today.
This is only for attenuation experiments, so there is no need to use Antenna Analyzer.

Again say, this module is not required for using the Antenna Analyzer. You do not have to buy it.

Thank you for reading



  1. Hi Ian!
    Today i try to use classical bridge.
    I have a question. Why the author of this device did not use such a bridge scheme. What problems did he encounter?
    My demo video:

    1. Hi Vitaly,
      A very good idea! It would be very interesting, haw some known impedances (e.g. 200 Ohm with 50 pF in series...) were measured with your bridge.

    2. Great experimentation and PCB ideas are great.

      There are several ways to measure the antenna.
      The method of measuring the antenna in EU1KY's AA uses a phase difference, so the circuit is different. The impedance is measured by the phase of the signal returned from the antenna.
      Therefore, not only 50 ohm antennas but also other antennas such as 75 ohms can be measured by setting values. This approach requires an OSL calibration method.

      Ian KD8CEC

  2. maybe we just don’t know something about that pitfall that caused the author to make a circuit on a transformer ...

    1. I'll add a little more to the explanation above.
      'classical bridge' methods transmit one signal over two lines. The circuits connected to the two lines are identical. Only 50 ohms are connected on one side and the actual antenna is connected on the other side.
      If the antenna is 50 ohms, the signal passing through the two lines will have the same intensity (because on side's 50ohm resistor == other side's 50ohm antenna). So the 50 ohm resistor that is the basis of the antenna is important.

      The phase measurement method uses the calibration to store the reference value. The 50ohm Calibration Kit was used.
      If the antenna is 50 ohms, it will be the same as the calibrated value.
      (because measured value using 50ohm resistor == measured value using 50ohm antenna)
      This way, the calibration kit becomes important.
      (This is an example - in fact, 50 ohms is not absolutely necessary when OSL calibrating)

      I will post this in detail later.
      Ian KD8CEC

  3. Hi Ian,
    would it be possible to add more bands for digimodes? 144 MHz, 474 kHz, 136 kHz?

    1. Mirek

      sure, it's very simple work. just add frequency for morebands.
      i will added more bands for digimode at version 0.5
      but, It may not be used at 144Mhz. This is because the Si5351 generates errors at high frequencies.
      It is expected to be possible if the frequency stabilizes.

      Ian KD8CEC

  4. Thanks Ian,
    I think there will be no problem on 144 MHz, I use TCXO.

    1. Mirek
      I will add it to the next version. please let me know the test results.
      Ian KD8CEC

  5. Hello Ian,

    This is Joe, HL5KY from South Korea. Thanks for the great job with firmware. There are quite big group of Korean hams experimenting with many ham radio devices. They discuss what they want to make and one of them (Shin, DS5TUK) makes it basically by group order. Lately they are making EU1KY AA with your firmware. Interestingly, we understood you are a Korean from your name on QRZ.COM. Some people thought it would be good to have Korean letters on the LCD and we wanted to contact you but no email address or something found on the net so this is the only way we can contact you.

    They share all the ideas through one of DAUM cafes.
    You can only see the list of the articles as the cafe is only open to the members. You can still find what kind of devices they are experimenting with.

    If it is ok for you, we would like to contact you through email. Maybe you can give me a line to my email ( Hope this does not put you to trouble.

    Joe HL5KY

    1. HL5KY
      Thank you for giving me some good info.
      I have not thought about multilingual yet.
      However, if users want a multilingual version, after the development of Version 1.0, I can prepare for conversion to another language.

      If you have a good idea, you can always send me an e-mail.

      Ian KD8CEC

    2. Thank you Ian,
      I've just checked your reply and understood your thought about the multilingual. I will talk to DS5TUK and if he has any offer for anything, he may contact you via email.

      Joe HL5KY.

  6. Hi, Ian!
    I noticed one artifact in LC measurement mode. it occurs sometimes.

    1. Thanks for the info, it's probably my mistake. I will change it in the next version.
      Please test in the next version.

      Ian KD8CEC

  7. Hello Ian I have one question. Is it possible to change the frequency of WSPR beaconing? No change band only change frequency(7,040100 or other?)


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