Amateur Radio

WSPR portable tests with HF loop antenna

Did some WSPR portable tests today during my lunch break with OM0ET MC-20 HF loop antenna. WSPR TRX from ZachTek controlled and powered by GPD MicroPC.

87 unique spotters in 12 minutes on 20 meter. Output is 200 mW.

Amateur Radio

FT8 contact with VK on 28 MHz

My first Australian contact on HF was done via FT8 on 28 MHz 2021-10-27 with VK6EI.

10 watt with IC-705 and EFHW 40-10 antenna.

Amateur Radio

WSPR with Sdrplay RSP1a

Testing RX of WSPR on 20 meter (14 MHz) with Sdrplay RSP1a, SDR Console v3 and WSJT-X.

Amateur Radio

Change broken relay Rot2Prog

The Rot2Prog rotor controller from AlfaSpid has four simple relays that several users has reported to be broken. This has also happened to me – I have a relay that has not function very well for several years. So I decided to try to replaced it.

These releay are very cheap and I found replacement at TME:

l:12VDC;16A/250VAC;16A/24VDC ROHS
Przekaźnik:elektromagnetyczny;SPDT;Ucewki :12VDC;16A/250VAC
Mfr: RELPOL Original part number:



Unmount the board

First remove the top cover by removing the four screws at the side of the chassi. Then remove the two screws holding the board, see image below:

The board is built nice, with ferrite on the input and output cable to prevent RF-noice. If needed to change the board, this can be easy done.

Remove relay

Then desolder the faulty relay. For me, it was one of the azimut direction relay, the one to the left:

It was a pain in the *** to desolder and remove this relay! I was close to give up and nearly destroyed the board. But finally, after two hours, I did managed to remove it. I can not understand why AlfaSpid did not mount a relay socket for easy change…

Solder the new relay

This was an easy task, just solder the 8 legs:

Function test

Now connect all the cables and try it. Hopefully it will now work again!

Good luck!

Amateur Radio

LNA and antenna switch with ESP8266

This is my first ESP8266 project, for control of my LNAs and antenna relays via a web interface. More info and code at my Github:

Amateur Radio

Simple full duplex relay switch

My setup for amateur radio satellites is SDR for receiving (RX) and Icom IC-705 for transmitting (TX). To my antennas I have two separate coax feedlines. Before, when switching band between RX and TX I was forced to manually change the coax feedlines connectors between SDR and IC-705.

I started to plan a simple relay switch to be able to switch fast and easy between TX/RX and UHF/VHF antenna – I call this a ”Simple full duplex relay switch”. The plan was this:

  • When no power to the relays the SDR is connected to the UHF antennas and IC-705 connected to the VHF antennas.
  • When 12V power to the relays the SDR is connected to the VHF antennas and IC-705 connected to the UHF antennas.

The relay used was this mini SMA relay by OK1CDJ. It can handle 10 watts (up to 20 watts according to hamshop.cz). The short coax between the relays are RG-405.
I have done SWR and loss measurements and it is very low. The original design and measurements can be found here:

This is the result, it works very good. Todo: put the relays in a nice box.

Amateur Radio IC-705

IC-705 WLAN doppler with OmniRig PstRotator

I got the PstRotator to work with OmniRig and IC-705 over WLAN. I’m using ”Icom Remote Utility” on Windows to set up the virtual COM-port. And I’m setting up OmniRig like this:

I had several problem getting the OmniRig to communicate with IC-705 via WLAN, but after re-installing to the OmniRig supplied with PstRotator (v1.18) I got it working OK. It is also working from SDR-Console V3.

So now it is possible to do doppler control of the IC-705 without any cables for true portable operations! See short video below: