[Milsurplus] R-390 3TF7 Ballast tube or substitute

[Al Klase]

Hi Robert,

Working from memory here:

Short across the 3TF7 socket, and substitute 12BA6's for the two 6BA6's 
in series with the ballast.

Add a wire or two to the ballast socket, and plug in a random 12-volt 
tube with a 300mA heater. E.g., 12BG7.

The current regulation here is only important if you have wild 
excursions of the AC line voltage.

Regards,
Al

WA5CAB at cs.com wrote:
> If anyone has an extra 3TF7 for sale, I just had a guy call me looking 
> for one. Also, I have a dim recollection of a thread on this subject 
> here where some substitutes were suggested or recommended. Anyone 
> recall that and what they were?
>
>
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-- 
Al Klase – N3FRQ
Flemington, NJ
http://www.skywaves.ar88.net/