[R-390] 3TF7 Ballast Tubes

[rbethman]

Ben,

There is not a "collective" viewpoint regarding these.

My view is *IF* you can get them, and don't have to give up an "arm and 
a Leg" to get them, then I'd stick with the 3TF7s.

The other possible method would be to place a 40 to 50 ohm 10 Watt 
resistor in its place.

I haven't gone the route of using a 12BA6 as of yet.

The resistor came in my '67 EAC, and worked just fine.  Currently I have 
one NOS 3TF7 left that is going into my St. J's restoration of the first 
contract Collins.

As is true in just about all instances, YMMV!

Bob - N0DGN

On 2/18/2011 4:35 PM, Ben Loper wrote:
>
> I came across some NOS 3TF7 Amperite tubes.  Should I make an offer on them
> or is the conventional wisdom to replace them with a 12BA6 tube.