[R-390] Cosmos PTO question

[Walter Wilson]

Phil,

Yes, there is a single linearity adjust screw to the right if the big screw
that covers the linearity screws.  It's more behind the can than in the
Collins PTO.  You'll probably only get about 3 to 5 KC adjustment out of the
endpoint adjustment screw.  Cosmos PTOs usually require removing one turn
from the endpoint adjust coil, which requires taking the cover off the PTO
to get inside and CAREFULLY making removing one turn from this coil.  One
turn is usually good for about 10 KC adjustment.  I have had one Cosmos PTO
where removing a whole turn was too much, but it sounds like yours needs
about one whole turn removed.

Of course after you've gone to all this trouble, you'll probably also want
to tweak the linearity screws.

I personally love having a Cosmos PTO in my own rigs, but they do require
more effort.  But once set, the linearity is better than any other, because
of the ease (relatively speaking) of the linearity adjustments.

Walter Wilson - KK4DF
http://r-390a.us
(REAL Radios: R-390A, R-390, T-368E, Ranger, Thunderbolt, KWM-2A)

----- Original Message -----
From: "Philip B Atchley" <ko6bb@juno.com>
To: <r-390@mailman.qth.net>
Sent: Wednesday, September 04, 2002 2:18 PM
Subject: [R-390] Cosmos PTO question


> Hello all.
>
> Well, I still have Dons R-390A on the test bench being worked on.  This
> is the receiver that has the Cosmos PTO.  As it turns out this sucker has
> the endpoint out by about 11kHz, and I thought the 6kHz on my Collins PTO
> was terrible before I corrected it!
>
> Anyway, I read through the Cosmos setup that I downloaded and it looks
> like a REAL pain in the rump to align.  I 'thought' that there might be
> an endpoint adjustment separate from the linearity adjustments and so
> removed the cap screw.  Apparently this is NOT the case.  But I'll ask
> anyway.
>
> QUESTION:  Is there a way to set up the endpoints separate from the
> linearity adjustments?
>
> 73 de Phil  KO6BB
> Loving home provided for wayward Boatanchor Receivers
> ko6bb@juno.com
> Merced, Central California
> 37.18N  120.29W  CM97sh
>
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