4

It might be harmonics of the oscillator, as you suppose, but it also might be that any mixer doesn't only produce the difference frequency of its two inputs ($|f_\text{RF}-f_\text{local oscillator}|$, here), but also higher-order intermodulation products (like $|2f_\text{RF}-f_\text{LO}|$ and $|f_\text{RF}-2f_\text{LO}|$). I think I've posted multiple ...


2

Everything works very well, but on some frequencies I hear loud AM broadcast stations. I think this is caused by harmonics from the VFO, but I am not sure. What you're possibly hearing is intermodulation distortions created by your receiver from the mixer and amplifier. A local AM broadcasting station has high radiated power, making the problem even worse. ...


2

After reverting MARS/CAP mod everything works as expected. I don't know whether the problem was caused by the mod per se or maybe just one of FCC cables was a little bit misplaced when the mod was made.


1

Found out what it is. Something really stupid. Before I had a TNC-PI. That TNC-PI modem just starts sending as sook as it gets data. The Kenwood on the other hand checks for a signal on the waves. If any; no packet transmission. And apparently this controlled by the squelch. I had the squelch set to "always listen" but then the radio things there's ...


1

SSB requires a signal from the microphone: only when you are talking there is a signal generated. For CW you need to connect a morse key or paddle to have output signal. When FM and AM are operational there is nothing wrong with your power amplifier. In case of a defect: check the microphone by listening to the AM or FM output signal and when that is ok and ...


1

That's an oddball receiver, employing a so-called Polyakov mixer. Its local oscillator is supposed to run at half the received frequency. For 80M, the local oscillator runs at about 1.8 MHz. The RF amplifier ahead of the mixer should be very linear...this one is biased weakly, and could easily distort when presented with strong input signals. This type ...


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