I've been 'PTO-ing'.... There are no fewer than 17 variations in 4 series PTOs.!! And that does
NOT take into account semiconductor changes.
MANY are merely changes in the decoupling of the DC power input, but there are a lot of other
changes as well. Looks like we were a little too optimistic thinking that you could just 'mix and
match' PTOs from different radios..........
I think your R-4A is an early one, and the first change is from the Common-Base buffer stage to the
Common-Emitter buffer in the 'late' R-4A'. There are a couple of differences in the T-4XB units,
but shouldn't be significant.
I assume you have tried subbing V8??????? Swap with V2? The PTO drives a 470 ohm resistor in the
cathode of that stage, noisy tube? Noisy resistor?
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Steve Wedge wrote:
That's the thing: it's a different PTO that was working properly before I
transplanted it.
Looks like I've got to try replacing the components on the filter board. Something is pulling the
frequency...
Steve Wedge, W1ES/4
"I can't complain, but sometimes I still do."
- Joe Walsh
If the above message appears, it came from Steve's Son of Laptop!
----- Original Message -----
*From:* Eddy Swynar <mailto:[email protected]>
*To:* Steve Wedge <mailto:[email protected]>
*Cc:* [email protected] <mailto:[email protected]>
*Sent:* Sunday, August 21, 2011 5:16 PM
*Subject:* Re: [Drakelist] You just know I'm not going to have any hair
left...
*/Hi Steve,/*
Well, I'm almost hesitant to say this, but ever since I re-soldered that
connection of the
33-pfd. temperature compensating tubular capacitor in the PTO of my
/T-4X/transmitter, I have
not---*/FINGERS/**/CROSSED!/*---experienced anymore warbling of my signal...
...In fact, I just checked it again a couple of hours ago. Still sounds
A-OK.
Now, that is /NOT/to say that the situation is 100% cured---I know better
than to publicly
proclaim anything like that, having been "burned" so many times in the
past! Hi Hi.
Best get that ailing PTO into a mailing container & ship it */POSTE
HASTE/*to Garey
first-thing Monday morning, for his evaluation of the doggone thing (and to
think that I once
thought that only my old /Heathkit SB-102 /was the proverbial ".../rig from
hell"!)/. *: >)*
*/~73~ de Eddy VE3CUI - VE3XZ/*
*/
/*
********************************************************************************************************************
On 2011-08-21, at 4:57 PM, Steve Wedge wrote:
Turned the R-4A on, with the replacement PTO from the T-4XB, and I am back
to square one. :-(
The frequency is jumping all over, occasionally chirps, then un-chirps.
Any suggestions aside from selling it cheap?
Steve Wedge, W1ES/4
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