Quote:
Originally Posted by old_coot88
Um.. by convention, in a series heater string, the first audio tube is usually at the bottom (ground) end of the string to minimize hum pickup. The OP might want to verify that the 1st audio tube's heater is indeed at the bottom of the string, in regards to his hum problem.
(Edit) Also, the rectifier (e.g., 35W4 etc.) is conventionally at the top of the heater string to minimize heater-to-cathode voltage. The audio output (e.g., 50C5 etc.) is usually the next one down the string.
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^^^ Interesting and makes sense electrically unless the fundamentals have changed since I was in school
IIRC even some transformer heater wiring and lead dress was very specific in something like a boat anchor comm radio or spendy audio gear and a there were
a only a few AA5 variants and virtually AA6 radios , the pre 1936 AA5 variants and the different tube envelopes & sockets for the same bloody AA5 circuits and the superior Zenith T.O. variants
Your edit that makes perfect sense . I tried to stay away from AA5 and AC/DC rubbish in the hobby but my 2 exceptions today are this deaf SWL specific model Hallicraftors S120 nostalgia radio for me and maybe a Zenith
Transoceanic H500 legitimate AA6 variant .
Benching TV & radios at a Magnavox AD when I was doing that there at 1967-1970 , Most of us understood a given signal path or output path tube order to function because you had to know it to fix the bloody things and where to start anyway .
we didnt have all these web forums and web sites or FUD
But your info here is not FUD .☺
EDIT 08.15.2017 20:30 PDT
I just assumed anyone replying to me would know the mid century AA4-AA5 tube order to function order correlation that hasn't changed much since
1936 and we had had to know all that in our sleep in school and how to to build an AA5 in the lab too .and that was H.S. advanced electronics lab before college which wasn't tubes anyway 3 periods a day BTY