It's not overly amazing that particularly simple radios aren't overly
impressive on FM; my ICF-7601 is an example for such a design: After an
antenna matching circuit, signals are fed directly to an IC that does
mixing to 10.7 MHz, has stuff filtered by a single IF filter (280 kHz or
whatnot) and then demodulates it with the help of a 2nd filter for
discrimination. The sensitivity to overload depends entirely on the IC
used, and with only one filter, selectivity isn't great.

The ICF-SW7600G(R) already uses a better design with an FM pre-amp and
two cascaded filters (though both are still rather wide at a spec'd 280
kHz). It can still overload quite a bit (that's the downside of the
rather good sensitivity), but fitting narrower filters (I had mine
changed to 110 and 150 kHz parts, respectively) improves selectivity
significantly, allowing some DX. (Same goes for the ATS-909, which,
modified with two 110 kHz filters, seems to be quite a popular choice
among FM DXers here.) I can only recommend such a modification if you're
regularly using the FM part. (The YB-400 apparently uses better filters
out of the box.)

Grundig's Satellits, BTW, used three cascaded FM IF filters. (The old
Sony ICF-5900 - along with the older ICF-5500 - also did, but these were
rather wide at - guess what - 280 kHz.)

For top performance, nothing beats a bunch of cascaded filters and
discrete components, of course. High-end FM tuners use(d) as much as
four cascaded filters.

Stephan
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Stephan Grossklass schrieb:

(Same goes for the ATS-909, which,
modified with two 110 kHz filters, seems to be quite a popular choice
among FM DXers here.)

And for real DX work, even narrower filters exist - 95 kHz, 80 kHz or
even 60 kHz. (Apparently for RDS to work properly with 80 kHz filters,
realignment of the receiver is necessary. Below 60 kHz, you obviously
get distortion - but which real DXer cares about that? .) Still, for
normal needs 110 kHz should be fine. A nice thing about that particular
receiver seems to be that you can also receive in the OIRT band (used to
be situated at 67 ... 73 MHz) used in Eastern Europe and Russia.

Stephan
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The Sangean ATS606A has very good FM but I've never tried to DX with
it.

On Thu, 1 Jan 2004 21:24:36 -0000, "Richard"
wrote:

David wrote:
Tivoli Model One has the best tough-signal performance of any 3 digit
FM radio I've run across. I can get 3,000 Watt stations 40+ miles
away perfectly.

http://www.tivoliaudio.com/pM1CLA.htm

On Wed, 31 Dec 2003 18:07:15 -0000, "Richard"
wrote:



I'm wanting a pockety sized PLL radio that will, on FM performance,
actually equal, at least an, old Grundig radio for sensitivity,
cross-modulation and image rejection!

Great :But not PLL or small portable.:c)