[R-390] RT301 current regulator tube

[wc4g@knology.net]

I have a couple more part numbers you can add to the list of substitutes:
Amperite TJ311M01     excellent substitute
Amperite  1HTF10        I'm checking, see pearls "ballast tube"

Happy New year
Regards,
Don WC4G

On Fri, Dec 31, 2021 at 2:53 PM Jacques Fortin <jacques.f at videotron.ca>
wrote:

> Hi all,
> I just found the V-I plot I made in 1984 from the 2HTF11B that came with my
> R390/URR when I found it.
> For the record, the Amperite 2HTF11B is a functional equivalent of the
> 3TF7.
> And for the sceptic ones, look at the TM 11-856, page 12, figure 11.
> At that time, it was right on the 300mA target between 10 and 18V.
> I will attach the pdf, but not sure it will "pass".
>
> And about beating that dead horse: Dallas Lankford already published in
> 2004
> that the best BFO + PTO stability was obtained by powering the filaments
> with a voltage regulator (he used a 7812, I believe).
>
> 73, Jacques, VE2JFE in Montreal
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