Re: Dx-ing

[Dan Strassberg <dan.strassberg@worldnet.att.net>]

At 05:48 PM 3/15/99 +0000, you wrote:

>There is one *major* image freq per station, = xmtr
>freq - 5.35 (?--10.7-:-2?):
>
>          107.9 = 102.55
>          106.7 = 101.35 (yes, on 'FNX xltr freq!)
>          105.7 = 100.35
>          104.1 =  98.75
>          100.7 =  95.35
>           96.9 =  91.55
>
I think you have that backwards. There is one major imaging frequency per
station and it's the station frequency plus (or is it minus?) (10.7 MHz
_times_ two). I forget whether the local oscillator (LO) on FM radios runs
above or below the frequency to which the radio is tuned. But the LO
frequency differs from the tuned frequency by the intermediate frequency
(IF). As far as I know the IF on FM radios is 10.7 MHz. In the absence of a
tuned amplifier ahead of the mixer, the radio is also sensitive to the
frequency 10.7 MHz on the other side of the LO frequency. In other words,
the two frequencies to which the radio is sensitive are separated by twice
the IF, that is, by 21.4 MHz--not 10.7.

- -------------------------------
Dan Strassberg (Note: Address is CASE SENSITIVE!)
ALL _LOWER_ CASE!!!--> dan.strassberg@worldnet.att.net
(617) 558-4205; Fax (617) 928-4205

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