[Hammarlund] HQ-129x RF Amp. 6SS7 pin 3

[RJ Mattson]

Hi Joel,
It seems the 6SS7's were chosen for economic reasons?
This poor HQ-129x was loaded with mods that I removed.
I alway restore my HQ-129x's to original sow's ear condition.
If I want a silk purse I use a later stock HQ-180AC :-)
bob...w2ami

----- Original Message ----- 
From: joel hallas

An interesting fact I noticed about 6SS7s when I was setting up my '129X was 
that their filament current was about half of most other RF/IF pentodes of 
the day. So even though others may work in their place, I would worry about 
the power transformer if I changed them out!

73, Joel, W1ZR

RJ Mattson wrote:

I think I found the answer. A popular mod was replacing the 6SS7 RF amp with 
a 6SG7. This mod only requires lifting pin 3 from ground on the RF stage 
socket. Why tying pin 3 to pin 5 is a mystery since both are 6SG7 cathode 
connections. Maybe it makes both tube types function in this circuit?