[R-390] Mech Filters/Ohm Reading

[Cecil Acuff]

Jon,

        I've not heard that a failure mode of the filters is shorted but 
more commonly open.  I haven't looked at the schematic for that area so I'm 
not sure what they do there but it's possible the unselected filters are 
shorted by the selectivity switch....just a guess though.  I'll try to find 
some time to take a look at the schematic and see if there is an explanation 
for what you are measuring.

Cecil....
----- Original Message ----- 
From: "Jon" <jonklinkhamer at comcast.net>
To: <r-390 at mailman.qth.net>
Sent: Friday, April 15, 2005 10:30 PM
Subject: [R-390] Mech Filters/Ohm Reading


> Hello,
>
> I'm wondering if anyone can answer a question for me. I'm basically going
> over the IF Deck, which is out of the radio and at this point.  I'm taking
> some ohm readings at J512 and everything checks out. Great. Now I took the
> cover off the Mech filters and looking across the terminals expected about
> 40ohms according to the book. However I'm reading 0ohms across 3 out of 
> the
> 4 filters. I'm getting nervous at this point. The 4th filter (4K) does
> actually read 41 ohms. Another data point is that I lifted the cap off one
> terminal of a filter that reads 0ohms and also took the wire off it. It
> turns out that with the wire off I'm reading about 58 ohms with or without
> the cap.  I'm going to bed now and saying a little pray. I guess I'm 
> looking
> for some help from the group. I'm preparing myself for the worst.
> Thanks in advance,
> Jon, KB1DC
>
>
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