[Boatanchors] EF Johnson thunderbolt

[KA2PTE]

Ok got a line on some used chokes and will be ordering soon.

Meanwhile I am trying to remember where I left off on this as far as the VR 
bias tubes go.

The original setup was a VR75 neon type for the operating bias tube, and (2) 
VR150 plus (2) VR100
in series totalling 550Vdc for the screen supply.

At one point another guy who restored a Tbolt said you can try a VR100 for 
the bias tube, which I did, but did not get good results.
I am not sure if I had left the screen tubes in the original config for that 
though.

I did seem to get somewhat better results with all the screen tubes as VR150 
types, and also I think with the operating bias tube
as a 150 as well, but at some point L8 gave out as its done 3 times so far.

I have the tube sheet, and I think for AB1 which the amps been modded for, 
using (2) 1K dropping resistors in series with the operating bias tube,
I am told thats good, but I also read the more screen volts the better. the 
only reason I can think that the VR100 tube was not a good one for the bias
are those dropping resistors? I am guessing there is a region I need to hit 
for the "sweet spot" on the bias for AB2 and 75 is the closest?

--
Steve Hearns
KA2PTE