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Old January 1st 04, 12:38 AM
Frank Dresser
 
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"R.F. Collins" wrote in message
...
This is a common problem with single conversion. If your front end is
too sensitive as on some Grundigs, you can overload the IF and get a
mixing product generated at 2 x IF frequency (455kHz) = 910 kHz. This
gives you the image at 910kHz above and below the actual frequency.
This is why more expensive radios are dual and triple conversion.

Jim



Images have nothing to do with overloading.

I read the linked web page and it says:

"Earlier in the year 2003, we made the mistake of taking seriously some
very enthusiastic posts on rec.radio.shortwave -- "the trailer-park
shortwave newsgroup" according to one of our acquaintances -- by
dim-wits who were overjoyed with a ten-dollar multiband radio with the
unexpected brand name "Bell & Howell""

"dim-wits"? "the trailer-park shortwave newsgroup" ?

As far as images go, there's only one. The signal mixes with the local
oscillator. Either the sum or difference signal is the desired signal.
The other signal is the image.

There may be other false signals from oscillator harmonics. But these
will be totally out of band, even VHF signals.

The page's insults and cheap shots on cheap radios continue:

http://www.home.earthlink.net/~srw-s...rundig-100.htm

It's just one crackpot's opinion, but I find insult humor unimaginative.

There's is a another image at the bottom of the page:

"by Steve Waldee, retired broadcast consultant, AM-FM transmitter
engineer, and audio specialist;"

If the original poster is still reading this, I'll suggest the problem
with FM DXing has little to do with PLLs and more to do with stereo. It
takes a lot more signal to get adaquate quieting with FM stereo.

I used to receive a Green Bay public radio station from Chicago with a
DX-440 on a semiregular basis. No more, the local stations around 88 -
89 Mhz are broadcasting almost full time now.

All the radios on the webpage, aside from the old Grundig, were bottom
end in both price and performance. There might be a pattern there.

Frank "trailer park" Dresser