Calibrating the KX2 by ear
I knew multiple radios would be useful!
On my last SOTA activiation, a couple of reports said I was off-frequency. At the weekend I setup the KX2 in the garden and arranged for a friend to listen to me and see if I was really off-frequency or if I’d somehow managed to knock the VFO or turn on XIT etc. on the mountain top and not realise.
We had a QSO and he recorded me a few times, once “normally” with the KX2, once with XIT on and then again using the G90. This was very helpful as I could hear my voice was a little high normally, and so I needed to XIT down. I’d guessed at 0.5 MHz but that was slightly too much. The G90 QSO was a nice benchmark as well. Whilst I was swapping to the G90 a US station called Micheal and he ended up talking to him for a while! It was Micheal who then suggested that as I’ve got two radios I can just use them to test myself, without having to deal with propagation and everything else!
The KX2 manual details what needs to be done to calibrate the radio. It’s fairly straight forward to do, but you need a reference frequency in order to calibrate it. This can either be from a signal generator or a known accurate broadcast. A well known one is WWV, the time station from America, which broadcasts on 5, 10, 15, 20 and 25 MHz. It announces the time and has a nice carrier to lock onto. I tried listening for WWV but had no luck on any bands. I did think I heard a carrier on 10 MHz and tried to use it to calibrate the radio but that put me wildly off.
However, all is not lost, as you can just manually adjust the reference frequency on the radio via the VFO dial, and that’s where listening to my own voice is beneficial.
It’s pretty straight forward to do, you put a dummy load on the transceiver you want to transmit from and I just had some wire plugged into the other. Perhaps they’ll both work with dummy loads, or perhaps even no antenna on the receiving station! I found that 40m was fine but 20m and higher frequencies were off by 0.3-0.4 MHz. So I iterated back and forth between changing the reference calibration frequency and then testing my audio again. After a few attempts I was pretty happy and everything sounded good to me.
In the end I went from 24,999,380 to 24,999,440. I’ve yet to try it on the air but my tests sounded good to me. I think if I wanted to improve the accuracy, I’d used CW and then I could lock onto the signal. I might still do that but for now my “by ear” will do.