I have decided to make the transceiver for 80 meter only. I may reconsider but I don't want to spend too much time on this radio
I intend to use it as a signals source for experiments with IRF510 based amplifier for 80 meter.
The power amplifier need some cooling. I have some PC fans that should be usable. They work great but they introduce hum in the audio. It comes via the power supply. No problem was seen when the fan was powered from outside the enclosure. Even when using the same power supply. Getting the fan power from within the radio causes a big hum. Adding capacitors does not help. I don't understand this.
One of the problems with this radio is that the audio is low in volume. So I have added an additional preamp. It works audio is at an acceptable level. I would like a bit more but it is Ok for now.
Unfortunately
My 20Ampere power supply has a problem. Once in a while it is not 13.8 V as it should be but 18+ V instead. That power is then stable at 18V for a while. Unfortunately this broke the audio PA. Smoke can out of it,
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