[ARC5] Receiver Drift

[millerke6f at aol.com]

Based on an experience I had some years back with a Motorola UHF commercial mobile radio that was being interfered with by Cell systems ut was determined that the mix was internal to the radio (Image of 2X LO and cell assignment).  However, the Cell signal was not entering the receiver via the antenna, but by the external power and control wiring.  The technicians that worked on the problem wanted to blame the Cell operator and it took a lot of "It's a Motorola Problem and not the Cell operator demonstrations" to make the point.  Motorola was not happy about the problem and it took a bit of documentation to make the point that their radio had a shielding problem or bypassing problem in connection with their wiring.  Motorola's solution was to move the IF and associated crystal filters away from the "Mix."  But my folks had to supply the labor.  tsk tsk.  The moral of this diatribe is to make sure the 920 KHz signal is entering via the Antenna system.


73


Bob, KE6F



-----Original Message-----
From: Robert Eleazer <releazer at earthlink.net>
To: arc5 <arc5 at mailman.qth.net>
Sent: Sat, May 18, 2013 2:42 pm
Subject: Re: [ARC5] Receiver Drift


A 915 KHZ trap sounds like a good idea; that's the only thing I can think of 
that might work.  That at least should get most of it.  The case has some large 
holes with copper (!) wire mesh over them for power supply cooling and it might 
let in some.

I have retuned an entire IF on an NC-155 to a different frequency and would 
prefer to avoid doing that again on anything.  And given that the 348 has a 
pretty good crystal filter it would be durn near impossible anyway.

Not sure why the AM interference is so much worse than it was.  

But anyway, I turned it on this morning and there was WWV right where it was 
last night!

Thanks

Wayne  
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