[R-390] IF module - snap on touch

[jrfke5ri at aol.com]

Try short spurts of "freeze" spray to pinpoint the problem.


John
KE5RI



-----Original Message-----
From: Bob Camp <ham at kb8tq.com>
To: r-390 at mailman.qth.net Group <r-390 at mailman.qth.net>
Sent: Fri, Feb 8, 2013 4:20 pm
Subject: Re: [R-390] IF module - snap on touch


Hi

It can also be a cracked cap or a fractured solder joint. Lots of light and good 
magnification are your friend ….

Bob

On Feb 8, 2013, at 8:12 AM, Gordon Hayward <ghayward at uoguelph.ca> wrote:

> To me this sounds like a bad connection where touching discharges a cap then 
things work until the cap saturates again.
> I've seen this before and this type of a problem is a bear to diagnose.
> 
> Cheers, Gord VE3EOS
> 
>> I had the IF module out while watching a 3 hr movie.  Put it in cold, turned 
it on, and gain was low.  Touched the 4K filter out
>> connection and snap, the gain came right up.  Let it warm up for a while and 
gain dropped off, touched the 4K filter again and
>> snap, gain came back up.  Did this 3 times but final time the gain did not 
come back up fully to -7V diode load with the 4K.  The
>> other filters were still at set gain.  Looks like for some reason the 4K 
filter is doing something, but maybe the switch is doing
>> something bad too?  When I touch any of the other filter output connections 
in their respective BW position, nothing happens except
>> a tiny pop.
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