12-06-2017, 01:01 AM
Russ;
I seem to recall that 6C4s were used in TV sets, so that may explain why they are cheap and easy to come by. I'm not sure what the specs are however, I will have to look them up in one of my tube manuals. You are right about the heater voltage not really being an issue, though I'm not sure how an indirectly heated tube will respond to being operated through a rheostat. Along these same lines I wonder if you could use another common, though slightly more expensive tube such as a 6K6G/GT, with the plate and grids tied together, those are 300 ma tubes as opposed to 250 ma for a 01A, though they might not work dues to the B+ in a 20s battery set being capped at 135 vdc.
Regards
Arran
I seem to recall that 6C4s were used in TV sets, so that may explain why they are cheap and easy to come by. I'm not sure what the specs are however, I will have to look them up in one of my tube manuals. You are right about the heater voltage not really being an issue, though I'm not sure how an indirectly heated tube will respond to being operated through a rheostat. Along these same lines I wonder if you could use another common, though slightly more expensive tube such as a 6K6G/GT, with the plate and grids tied together, those are 300 ma tubes as opposed to 250 ma for a 01A, though they might not work dues to the B+ in a 20s battery set being capped at 135 vdc.
Regards
Arran
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