In Reply to: RE: Measure heater voltage---Important!! posted by drlowmu on January 26, 2015 at 06:24:30:
There's another potential problem with the 40M design regarding the 6SL7. At least in the version I had, the 6SL7 heaters were referenced to ground which put the heater-cathode voltage over the max rating due to the split load inverter. As I recall, the H-K was around 110 or 130v. I burned up a couple NOS 6SL7 tubes before figuring out that issue. Fortunately the tubes I liked best in that spot (Brimar CV1985) were not bothered by the high H-K voltage. Had I kept the amps, I would have added a divider network off the B+ with roughly a 65vdc tap and connected it to one leg of the heater supply, which would have allowed more flexibility with other 6SL7 types.
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Follow Ups
- RE: Measure heater voltage---Important!! - Salectric 07:25:46 01/26/15 (5)
- Dennis Had .....reach him ......??? - drlowmu 07:49:35 01/26/15 (4)
- RE: Dennis Had .....reach him ......??? - lovetube 16:12:02 01/26/15 (3)
- Just a LITTLE more please ..... - drlowmu 16:59:21 01/26/15 (2)
- RE: Just a LITTLE more please ..... - lovetube 17:28:51 01/26/15 (1)
- RE: Just a LITTLE more please ..... - Tre' 18:34:37 01/26/15 (0)