[R-390] Cosmos PTO question

[Roy Morgan]

At 06:18 PM 9/4/02 +0000, Philip B Atchley wrote:
>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.
>QUESTION:  Is there a way to set up the endpoints separate from the
>linearity adjustments?


Below is an earlier post from Tom Marcotte which indicates that changing 
the turns on the corrector inductor, or making a new inductor is the thing 
to do. I suspect that getting the thing out of the case and locating some 
wire the right size is the hardest part of this procedure.

(Apparently the corrector disk runs the slug of the corrector inductor in 
and out as the thing goes through its range.)

Tom may well have a response.

If you are loathe to take the thing apart, email me.  I might be talked 
into working on it for you.

Roy
Who recently got an unused Cosmos.


>From: "Tom M." <courir26@yahoo.com>
>Subject: Re: [R-390] R-392 Dubrow PTO endpoint
>To: Francesco Ledda <frledda@attbi.com>, r-390@mailman.qth.net
>Sender: r-390-admin@mailman.qth.net
>Date: Mon, 8 Apr 2002 05:56:43 -0700 (PDT)
>
>I've never worked on a Dubrow, but I think it is the same as a Collins.
>
>This is a very common problem.  One author wrote that this mod is not worth
>doing, but I can't disagree more.
>
>What you'll need to do is remove the cover, find the PTO endpoint adjusting
>coil, and remove one turn from it, and then start over.
>
>I find on some PTO's that it is easier to make a new coil than to trim the old
>(Cosmos in particular), but that will be your call.
>
>This will keep you in business for the news 30 years or so.
>
>73 Tom N5OFF



>--- Francesco Ledda <frledda@attbi.com> wrote:
> > All,
> >
> > I am struggling with a Dubrow PTO for my 392.
> >
> > The endpoint is about 3 kHz off, and I am at the limit with the coil
> > adjustment.
> >
> > Any suggestions?
> >
> > Best Regards,
> >
> > Francesco Ledda


- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
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