[R-390] Testing Collins Mechanical filters:

[Dennis Wade]

Does anyone offer a filter rebuilding service?  I have a 16, 8 and
possibly a 4 kc filters in need of repair.


         Dennis


On Fri, Apr 24, 2009 at 1:47 PM, Tim  Shoppa <tshoppa at wmata.com> wrote:
> KIORQ writes:
>> But the audio is not very loud.
>> Anyone have any ideas?
>
> Ohmmeter tests:
>
> Across input and output coils of each filter, it should
> be 50 to 100 ohms. (Web says 50 to 60 ohms, my
> memory says closer to 100 ohms...). This is the
> DC resistance of the transducer coil.
>
> Between the signal pins and can should be
> very very high resistance, bigger than megohms.
> If it's leaky at the megohm level AGC action will
> reduce the gain.
>
> If there is leakage but only between one end and
> ground, it may be possible to isolate the filter can
> from ground.
>
> Standard reference on rebuilding filters: http://www.delphelectronics.co.uk/filter390a/
>
> I kinda wish that I would get laid off of my job
> so that I could have time to fix my bad mechanical filters
> (and all the other old radios laying about the shack.)
> As it is others are getting laid off and I have to work extra
> hard to pick up the slack.
>
> Tim N3QE
>
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-- 
Dennis L. Wade
KG6ZI
Carmichael, CA