SW/MW only Radio to FM Radio

DickCappels

Joined Aug 21, 2008
10,153
As you might gather Dodgydave's comment, there is little in common between an AM/SW receiver and a broadcast band FM radio until you get to the audio stage. Converting would require massive rework that probably won't work well when you are done with it.

The local oscillators, front ends, IFs and detectors are all different and are designed to operate at different frequencies. .
 

BR-549

Joined Sep 22, 2013
4,928
It will depend on the SW/MW receiver. And it would not be high quality audio, like FM usually is.

The AM receiver would be set at a constant frequency. A tunable oscillator(down convertor).....this feeds the AM ant. input. This negates the AM tuning bandwidth.

How the receiver behaves, depends on the IF bandpass slope. If the bandpass is sharp(not bandwidth...the slope of the bandwidth)......narrow band FM is probably the only FM that could be received. If the IF bandwidth slope is wide, then wideband reception should be possible. Not high quality though, but understandable.

One would tune the down converter until you hear the characteristic thump of a dead carrier on AM.

Now slightly tune the AM receiver.......it acts like a band-spread control. One would want to tune off center of the dead carrier. Try both sides of slope.

But anybody this is serious about FM, would not fool with this. They would use a properly designed FM radio.

Converting a AM rig to FM that way...........is only meant for zombie times.
 

dendad

Joined Feb 20, 2016
4,451
If you want to mod the radio to FM, about all that you can make use of is the case and speaker. Toss all the rest. Buy an FM radio, and put its guts in the old case.
As everyone else has said, it is just not worth it.
Maybe if you had a really nice classic wooden cabinet radio that you liked the look, then go for it, but for the radio shown, it is an exercise in frustration. Start from scratch and make yourself a decent case with good speakers. That would be a better way to go if you don't just want to buy an FM radio. They can be found tossed out or purchased for almost no money.
 
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