Richard wrote:
I hear that FM RX's are pretty complicated affairs. Most FM DXers it seems
just modify commercial sets. Reduce bandwidth from say 230Khz to 110 Khz. I
suppose that going this way has quite a lot of merit. Cheaper probably.

It's certainly the most bang for the buck. Really, a good FM receiver
isn't much more complicated than a good AM receiver -- but a
bare-bones-just-barely-receives-the-strongest-stations FM receiver is
quite a bit more complicated than a bare-bones-..... AM set.

Usually you can reduce the bandwidth of a FM receiver by simply removing
the monolithic ceramic filters and replacing them. I've done that on my
Technics ST-G50; at my location 30 miles outside Nashville, I have
received at least one DX station on every frequency that doesn't have a
local. (yes, that includes the frequencies adjacent to 100,000-watt
locals)

Forget what I paid for the filters - it was definitely less than $5
apiece. My tuner needed two.

=============================

Regarding going to 20KHz bandwidth...

In DX situations with heavy interference, a very narrow bandwidth might
be helpful for identifying DX stations. The programming will be mostly
unintelligible in a 20KHz bandwidth, but maybe it'll be more
intelligible than it would be against the interference from adjacent
channels in a more reasonable bandwidth.

I occasionally use the narrow filters in my TH-F6 HT to DX television
audio. Nobody would dream of listening to that audio for entertainment
but one can identify things they'd never ID on a TV set.

Don't know anyone who's tried putting a 10.7MHz IF 20KHz or similar
bandwidth filter in a FM broadcast tuner. You'd want it to be one of
multiple bandwidths, so you could select something more reasonable for
stronger signals.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com