12-12-2025, 06:51 PM
Rob;
The specs I found give the plate current as 32 ma at 250 vdc, and the screen grid at 10 ma, at 100 vdc the plate is 9 ma, and the screen 3 ma, so the 180 vdc B+ volts for B+ was obviously chosen to get the maximum performance they could out of an #84/6X5 based power supply without blowing it up. https://frank.yueksel.org/sheets/155/6/6K6G.pdf This was from a Brimar tube manual which was a division of ITT over in Britain. Unfortunately it doesn't give a push pull rating.
Another trick Philco did was to use loctals with 150 ma heaters in them, the same as what they used in their AC/DC sets, that likely reduced the burden on their power supply as well, at least the heater winding. I must say that they did a good job, unlike the contemporary Brand Z models of that era most of the Philcos I encountered still have their original power transformers.
Regards
Arran
The specs I found give the plate current as 32 ma at 250 vdc, and the screen grid at 10 ma, at 100 vdc the plate is 9 ma, and the screen 3 ma, so the 180 vdc B+ volts for B+ was obviously chosen to get the maximum performance they could out of an #84/6X5 based power supply without blowing it up. https://frank.yueksel.org/sheets/155/6/6K6G.pdf This was from a Brimar tube manual which was a division of ITT over in Britain. Unfortunately it doesn't give a push pull rating.
Another trick Philco did was to use loctals with 150 ma heaters in them, the same as what they used in their AC/DC sets, that likely reduced the burden on their power supply as well, at least the heater winding. I must say that they did a good job, unlike the contemporary Brand Z models of that era most of the Philcos I encountered still have their original power transformers.
Regards
Arran
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