[R-390] R-390A Alternatives for regulator 3TF7 - 12BH7, 12BY7, etc

[Jacques Fortin]

The two solutions work equally well, but using 12BA6s consume less power(!).
I always had concerns about replacing the 3TF7 with solid-state
"substitutes".
I tried this on the HRO-60 also but never been satisfied with the results...
using a 6V6 there is the most convenient.
About the 3TF7: if ever someone runs across a 2HTF11B, it can be used,
because it measures identical to the 3TF7.
For the ones that have doubts, just look in the Collins R-390 manual (order
14214-P-51) dated Oct. 23, 1953 or the TM 11-856 on page 10, fig. 11 and
just read what is stamped on the IF chassis for RT512.

73 to all,
Jacques, VE2JFE


-----Message d'origine-----
De : R-390 [mailto:r-390-bounces at mailman.qth.net] De la part de Craig
Envoyé : 8 avril 2016 09:25
À : 'Larry H' <dinlarh at att.net>; '390 List' <r-390 at mailman.qth.net>
Objet : Re: [R-390] R-390A Alternatives for regulator 3TF7 - 12BH7, 12BY7,
etc

Another option to replace the 3TF7, thus saving money for good whiskey:
Jumper pins 2 & 7 on the 3TF7 socket and replace the 6BA6 tubes for the BFO
& PTO with 12BA6 tubes. 

Regards,
Craig

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Larry H
Sent: Thursday, April 07, 2016 9:35 PM
To: 390 List
Subject: [R-390] R-390A Alternatives for regulator 3TF7 - 12BH7, 12BY7, etc

If you have the 2 wire change on the regulator socket, these can be plugged
in and work well: 12BH7, 12BY7, 12CT8, 12DQ7, and 12FX8. Regards, Larry

     
  
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