[R-390] Need value of R235 from a RF deck

[Craig C. Heaton]

                                                                 Stop The
Presses

Hello All,

Major announcement follows! The Motorola and Amelco have come to a
compromise! Hence forth known as the "Springfield Compromise". 

To refresh memories, the Amelco followed me home I think sometime late 2006.
It was in almost new condition, original tubes, green head captive screws
untouched, etc. But like most/all R-390A's, had those BBOD's to deal with. 

So it got the recap treatment and a good alignment. At this point I noticed
the crystal calibrator was not working properly. I tried a few things; like
the H202 from the Motorola, different tubes, De-Oxit on the pins of H202 &
tubes, etc. Really didn't feel up to pulling the RF deck out so soon. I'd
deal with it later. Another tid-bit, in attempts to trouble shoot the
crystal calibration issue I was prying the 200KC crystal from the H202 when
it popped out and bounced on the floor several times. Didn't work at all
after that. Tried a crystal that someone sent me and no luck there either.
Even the crystal from International hasn't worked in the Amelco. 

Tonight I tried the H202 from the Motorola again. It worked in the Amelco;
the adjustment for the air variable zero beats WWV about mid-range. Strange
enough the H202 from the Amelco works in the Motorola with no adjustment
needed. 

So, with a few new silver micas, couple resistors, and the H202 from the
Motorola; I now have everything working on the Amelco. The Motorola is happy
with a crystal from International. And I getting pretty good at removing &
replacing RF decks in R-390A's. 

Goes to show you, one R-390A isn't enough, gotta have at least two. 

Thanks for any & all support/ideas.

73's
wd8kdg
Craig

PS: Hope it still works in the morning!

-----Original Message-----
From: DJED1 at aol.com [mailto:DJED1 at aol.com] 
Sent: Wednesday, July 30, 2008 6:40 PM
To: wd8kdg at worldnet.att.net; Flowertime01 at wmconnect.com;
r-390 at mailman.qth.net
Subject: Re: [R-390] Need value of R235 from a RF deck

Boy Craig- you've got an interesting problem, but the diagnostics are very  
helpful.  You've narrowed it down to the crystal oscillator, IMO.   When the

crystal is running at 200, you get a good 100 KHz multivibrator  signal.  It

clearly shouldn't start at a non-crystal frequency.  There's only a few 
components in the crystal oscillator, and you've  checked them all, so I
would suspect 
either a bad crystal or connection.   Have you cleaned the tube pins and the

crystal oven and socket pins, and checked  the tube?  You might try swapping

other 5814s in and see if one gives  better behavior. And try again swapping
the 
crystal. something is loading the  feedback path through the crystal.  I'd 
leave V206 out and work on getting  the 200 KHz oscillator to start up on 
frequency every time.  Good  luck
Ed 



**************Get fantasy football with free live scoring. Sign up for 
FanHouse Fantasy Football today.      
(http://www.fanhouse.com/fantasyaffair?ncid=aolspr00050000000020)