[BC] Overcrowding & noise floor on AM

[WFIFeng@aol.com]

In a message dated 03/19/2007 11:51:50 PM Eastern Standard Time, 
amstereoexp at yahoo.com writes:

> In fact, I have one Panasonic
>  stereo system whose dial is marked from 530 to 1700 kHz, but there's so
>  much extra range on its dial that I think it could tune from 450 to 1800
>  kHz if there was anything to hear!

You may be surprised... it may only go from 520 to 1730 or so. The physical 
construction of the variable capacitor is the limiting factor, here. It is not 
uncommon to have that style tuner actually start to "fold back" a little at 
the band edges. For example, as you dial down, it will reach, maybe, 520Khz, 
then move back up to maybe 530 before reaching the end-stop. At the other end o
f 
the dial, it may go up to 1730, but then drop back to 1710 as you hit the 
other end-stop. Pop the cover, and watch the action of the variable capacitor, 
and 
this behavior will make more sense as you watch the mechanics of the plates 
meshing and unmeshing. That's why they would often leave a portion of the dial 
scale unmarked at the far extremes... the actual tuning range there is "odd".

Willie...




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