[Hammarlund] Drift of Newer Hammarlunds? was Re: Old Hammarlunds - 6K8

[Kenneth G. Gordon]

BTW, I must make a clarification: although the HQ-129X and many other 
receivers use the 6K8 (or the 12K8) as the mixer/oscillator, that tube is 
possibly the noisiest mixer tube ever designed, and I thoroughly hate it.

ENR (Equivalent Noise Resistance) of the 6/12K8 as a mixer is something 
like 360,000 ohms, while using a 6AC7 as a mixer is on the order of 1500 
ohms, and the mixer mod using a 6ES8 as used in the 75A4 has an ENR of 
160 ohms. 

Nonetheless, the 6/12K8 has exhibited very stable operation as an oscillator. 
Witness the ARC-5 and SCR-274N series of receivers, which ALL used a 
12K8.

Ken W7EKB