The biggest issue with having two receivers with the same IF is local
oscillator leakage into the other receiver, causing it to have some
sensitivity on the opposite frequency. Good shielding between the
receivers is important.
--
Jim Barbour
WD8CHL
Neil McKie wrote:
>
> Hey Michael ...
>
> I think you got it wrong this time, not a first but almost ...
>
> Motorola Manual Part Number 68P81045E70-O-01 dated 8/1/82:
>
> Page "Receiver Alignment Procedure" Motorola No. PEPS-26663-C
>
> Left side of the page - bottom:
>
>
> F R E Q U E N C Y C A L C U L A T I O N S
>
> FREQUENCY (MHz) CALCULATION
> ----------------- -------------
>
> Fc - 10.7
> 136-174 Fo = -----------
> 3
>
> Where Fo = crystal frequency; Fc = carrier frequency
>
> ---------
>
>
> instruction manual revision WMR-0070 dated 12-17-82
>
> Page "Receiver Alignment Procedure" Motorola No. PEPS-26663-C
>
> ... says the same thing ...
>
>
> Looks like low side injection to me.
>
> Go to bed Mike .... it's 1:20am your time ... 73,
>
> Neil - WA6KLA
>
>
> Mike WA6ILQ wrote:
>
>>At 02:52 PM 11/29/04, you wrote:
>>
>>
>>>I have read a few comments in the past about the need for changing
>>>the crystal from one side of the operating frequency to the other in
>>>a Mitrek.
>>>I am not sure I will be wording this properly so please be patient.
>>>
>>>I will have two repeaters at the same site which are Mitrek
>>>conversions.
>>>One repeater is on 145.210 MHz (neg. offset) and the other repeater
>>>is on 147.240 (pos. offset).
>>>At present the 145.210 repeater is not a Mitrek but when I am
>>>finished the conversion it will be replaced by the second Mitrek.
>>>
>>>I would appreciate comments re experiences (ie problems) encountered
>>>if both receivers have the same frequency crystal.
>>>
>>>thanks
>>>
>>>Bruce, VE1II
>>
>>The standard 136-174Mhz Mitrek configuration uses high
>>side injection, with a 10.7 MHz IF.
>>
>>And remember, the 147.24 repeater will be listening
>>to 147.84, and the 145.21 repeater will be listening to
>>144.61 - with over 3mhz of RX to RX separation I don't
>>see a problem at all.
>>
>>And if you are referring to the two repeaters being on
>>the same channel simultaneously, well, that's what
>>two different PL tones are for - set up repeater 1 on
>>tone A and repeater 2 on tone B.
>>
>>Or am I not understanding the question?
>>
>>Mike WA6ILQ
>>
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