[R-390] 12BH7A

[Bernie Doran]

If one is really fussy about appearing totally stock, carefull bend some 
small wires around the pins on the 3tf7, then rub the 12 of of the 12 volt 
replacements. Isn't that being a little silly though? perhaps  you might 
have a larger problem if you are that concerned.   Bernie W8RPW
----- Original Message ----- 
From: "Todd, KA1KAQ" <ka1kaq at gmail.com>
To: "R-390-List" <r-390 at mailman.qth.net>
Sent: Sunday, January 27, 2013 12:14 AM
Subject: Re: [R-390] 12BH7A


> >
>> 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
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