[R-390] 12BH7A

[Todd, KA1KAQ]

>
> kinda like getting sumpin' for nuttin'
>


But if you have to remove a module to solder jumpers into place, swap PTO
tubes or whatever else, it's no longer something for nothing. (o:

I understand that Ron's radio has apparently been modified already, but it
still baffles me that more folks either don't use or perhaps aren't aware
of the simple resistor substitution solution (RSS), particulalry since the
ballast tube is referred to as a 'current limiting resistor'. A basic 40-50
ohm 5-10 watt  resistor (think I used 43 or 45 ohms) is all that is
required. Simply bend the leads so they don't come into contact with
anything nearby (or dress them with spaghetti if you're really worried) and
insert into pins 2 and 7 of the socket. No soldering required, the leads
plug in just as tube pins would. Allen Bradley carbon comps might not be
the best choice if you receiver lives in a humid environment.

If you've ever overcome with guilt or insanity and want to reinstall a 3TF7
in the socket, just yank out the resistor. It'll take more time to align
and stuff the tube back in. Beyond completing the circuit, the ballast tube
serves no real function in today's world. Elevated line voltage is far more
of a concern than poor regulation. It was supposed to be removed from the
cost-reduced R-390A design but somehow managed to hang around.

You can even hide said resistor inside of a tube shield if the Originality
Police have you staked out.

de Todd/'Boomer'  KA1KAQ/4