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FM Overload

M

MarioMania

I'm in Citrus Height

I'm near like 4 Stations KYRV/KRXQ/KKDO/KUDL

My Sony AM/FM Walkmans & my Sony ICF-P26 Overload like crazy on Open Channels

My Grundig doesn't or any other GE Radio I have
 
This is a good start for a thread for all use FM dxers out their. Thanks Mario...

I'd be curious to see which radios can discriminate better than others, for FM DXing.

To be honest, i'm not sure what it's official name is for it, be it overload or imaging. I use both terms.

I can't say I've heard it on my GE SR-2, but the selectivity is not the greatest, near strong stations.

Both my Sangeans ( D5 and D4W ) are excellent on discrimination, but they are just not as sensitive as my Tecsun PL880. My Sony ICF-EX5MKII has serious issues with imaging/overloading. Jay Allen rates this radio as a 4 star on FM, not sure why. He also gives the PL660 the same rating ( 5 stars ) as the 880. The 880 walks all over the 660 when it comes to DXing FM. Both my little Tecsun radios though ( 398MP and 310et ) are also excellent when it comes to discrimination, and they are very sensitive and selective as well.

Lastly, the revered Panasonic RF-2200 is outstanding on FM, but this radio is not easy to come by today.

I'd like to know what radios are just as good as the PL880 or the Sangeans, when it comes to FM discrimination.
 
Sounds like it could be RITOIE also (2A-B and 2B-A where A and B are two strong signal frequencies). Some radios need a preselector to reduce this, even if excellent in other ways. The MR-78 and MR-80 are all but immune to RITOIE, but since IBOC, the selectivity is no longer as useful for first adjacents in many areas. I don't know if anyone has come up with a method to reduce IBOC sidebands.
 
Let me add to this question, does anyone have problems with stations that are separated by the standard intermediate frequency?
That was never an issue with full power stations, but I do not think that spacing is considered for translators and LPFM's.
In Miami - Fort Lauderdale, short-spaced stations are on 88½ and 99.1, but they seem to co-exist OK.
 
The IF Beat Frequency problem seems to be most noticeable on distant grandfathered high ERP stations during strong tropospheric events. Under certain conditions, the distant station is heard all over the dial, particularly when a nearby station without compression plays Classical Music with very soft passages. Tropo can make any 10.6/10.8 MHz separated station as strong as it would be if it were at less than the required distance apart. A nearby radio with a strong radiated local oscillator tuned to the same station can also create the same effect, hearing a station all over the dial. This has been a puzzle for many engineers until they figure out what is happening. My next door neighbor, the accountant who did the financial inventory when WAPC/WHRF and WPAC/WBLI when Metrocom sold them, had this happen every night, probably because a neighbor was tuned to the same station, WGMZ/WCRZ. She called their engineer out from our local Metrocom station, WGMZ, to investigate. Metrocom sold some of their properties to Beck-Ross Communications. Ross, attorney George H. Ross, later became famous on The Apprentice and as Donald J. Trump's right hand man. WAPC and WPAC were where Rick Sklar worked early in his career. There's always a story to connect the dots.
 
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MarioMania said:
But I don't understand why Sony Radios built like that on FM

AM is fine
Click to expand...

(Thought I answered this earlier, but it must have erased itself....)

Sony portables usually have pretty hot IF chips, which may cause them to overload on FM sometimes, especially if you are within a couple miles of the towers.

The CXA1019 chip -- common to many Sony Walkmen, clock radios (Dream Machines) and the Sony ICF-38 -- is pretty hot on both AM and FM. The CXA1019 has RF amp sections on both FM and AM.

I think Sony used this chip in their portable radios because of the smaller loopsticks in those radios; and because when Walkmen came out, one of the complaints about FM reception was dead spots while moving around. Hence, the high gain on FM.
 
Now that's better

I'm going to Vallejo prob this weekend, So I bring my Sony ICF-P26

I don't think I will have a problem there on FM
 
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