[R-390] Will it ever be the same?

Thu, 26 Jun 2003 21:19:05 -0400

Yes, and better!  I have done that service on a Comos, it's not that bad
once you get the can taken off.  The slug can be screwed back into the coil
when you open it.  I have an article on Dave Medley's page
http://www.davemed.com/

showing how I had to completely rebuild a Cosmos.  You arent faced with that
much however just to remove a turn from the adjustment coil.    However if
the linearity or tracking is off, adjusting all the little screws can be a
daunting task.  However, adjusting Cosmos linearity with those screws is far
easier (to me) than the linearity stack in a Collins PTO (I have done both).

There is some PTO information on this page:
 http://www.r-390a.net/Pearls/

Also try http://www.r390a.com/

73 Jim N4BE
----- Original Message -----
From: "Phil Atchley" <[email protected]>
To: <[email protected]>
Sent: Thursday, June 26, 2003 8:14 PM
Subject: [R-390] Will it ever be the same?

Hi.
Well, today I replaced the deadly capacitors in the IF strip as I wanted to
check out the PTO thoroughly and didn't want to risk taking out a mechanical
filter.  I'm going to have to wait till the first of the month to order all
the parts needed to re-cap this set properly, though I had enough to do
"most" of the IF strip.  (I've been working to too many BA's lately and ran
out of new parts).

Anyway, to make a short story long, the endpoint of this Cosmos was off by
about 6KHz.  I thought, aha! I should be able to pull it that far.  WRONG!!
I got it to where the error is about 3 KHz and I think the slug dropped down
into the PTO 8^((  At least that is the way it appears and the unit
"rattles" when I shake it.

SO, now I have pulled the PTO, removed the outer cover and am faced with
having to pull the entire unit apart.

I had previously downloaded a LOT (250 MB worth) of R-390 information and
found the two files on calibrating the Cosmos PTO.  I remember reading about
removing a turn from the coil, I just haven't found that "page" yet.  I
"thought" I had complete teardown/service information on this too but
haven't found it yet.  Anybody know where that info might be located?

QUESTION;  Will this poor thing ever be the same again?  I was sorry to see
a Cosmos PTO in this receiver and it looks like I wasn't far wrong. All my
personal R-390A's to date had Collins PTO's, set the end point and forget
it, they worked fine and were well within specs on linearity.

73 de Phil, KO6BB

****************************************************
*  DXing THE WORLD WITH THE FOLLOWING EQUIPMENT.   *
*  RECEIVERS:                                      *
*    '67 EAC R-390/URR Surplus Receiver with a     *
*            HAMMARLUND HC-10 Sideband adapter.    *
*    YAESU VR-5000 Wideband,  REALISTIC DX-392.    *
*    Home built Longwave "Hybrid" CW receiver.     *
*    Others which pass thru or are waiting repair. *
*  ANTENNAS:                                       *
*    Coil Loaded 18.5 Meter Long Sloper.           *
*    Roof mounted Hustler 6BTV 6 band Vertical.    *
*    Scantenna Scanner antenna at 7 Meters high.   *
*  LOCATION: Merced, Central California.           *
****************************************************

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