[R-390] 390-A VFO Rebuilders?

[Cecil Acuff]

Also make sure it's not just driven hard against one of it's end stops which 
can happen if it is reinstalled out of sync and it reaches it's stop before 
the mechanical drive train reaches the 10 turn stop point.

That can make it appear to be locked up...

It can also be permanently damaged that way also if taken too far.

Disassembly and a visual inspection should help to figure out if it's stuck 
all the way in or all the way out.

Just my 2 cents worth...

Cecil...
----- Original Message ----- 
From: "Paul H. Anderson" <paul at pdq.com>
To: "W Gladhart III" <willysgarage at cox.net>
Cc: <r-390 at mailman.qth.net>
Sent: Saturday, April 21, 2007 8:25 AM
Subject: Re: [R-390] 390-A VFO Rebuilders?


>
>
> On Fri, 20 Apr 2007, W Gladhart III wrote:
>
>> Hello Group, I've been awarded the care of a Collins R-390A. It was 
>> received upside down with the VFO removed. The VFO shaft is stuck solid. 
>> I picked up a beater replacement from Fair mainly for a set of 
>> bearings(?) but I don't think I should attempt messing with it. Can 
>> anyone recommend someone that can repair and align this VFO so I can 
>> power the unit up and find what other surprises it holds in store?
>
> Wes,
>
> I suggest this strategy...
>
> Make sure it is the VFO and not the front panel bushings or other parts of 
> the RF deck.  Do this by removing the VFO from the radio.  The tuning 
> shaft should turn freely with light fingertip pressure (do not force). You 
> have an example from Fair to help you see what might be normal.
>
> If it is stuck then, you are most likely doing triage on it - it likely is 
> corroded inside, badly bent, or otherwise generally unrepairable, IMHO.
>
> You can check for this by taking the cover off, which is fairly safe to 
> do - in my opinion you're just looking to see if there is something 
> grossly wrong that can be readily fixed.  So, pull stuff off, save the 
> parts, and see if you can locate the problem - bent shaft, corroded 
> bushings, broken parts.
>
> Another perfectly reasonable approach, if the VFO itself is stuck, is to 
> set it aside as a spare (or mid-winter repair project), buy another one 
> that can be restored or used, and go with that one.
>
> I lean towards replacement rather than repair because R-390A VFO's are 
> relatively available at not too much money, and repair of this type of 
> problem is best done 'because you want to' - not because it makes time or 
> money sense to do so.
>
> This is all my opinion, and clearly, there are many reasonable points of 
> view on this.
>
> Paul
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