Hi all
Surfing on the web I’ve found a schematic of an interesting pse amplifier. In the output stage there are three 6550 in UL. I’ve never seen before such a solution, so I’d like to know what you think about the connection of more than one screen grid to the same UL tap (43%).
Do you think it could produce any problem to the local feedback mechanism?
Thanks
Mark
Surfing on the web I’ve found a schematic of an interesting pse amplifier. In the output stage there are three 6550 in UL. I’ve never seen before such a solution, so I’d like to know what you think about the connection of more than one screen grid to the same UL tap (43%).
Do you think it could produce any problem to the local feedback mechanism?
Thanks
Mark
Mark,
I don't see why it can't be made to work well. The 3 paralleled O/P tubes need to be very closely matched for gm and reasonably well matched for plate current. "Fixed" bias, with an individual adjustment for each tube, allows the idle current for each tube to be set, "perfectly". "Fixed" bias implies modestly sized grid leak resistors. So, low impedance driver circuitry is in order.
I don't see why it can't be made to work well. The 3 paralleled O/P tubes need to be very closely matched for gm and reasonably well matched for plate current. "Fixed" bias, with an individual adjustment for each tube, allows the idle current for each tube to be set, "perfectly". "Fixed" bias implies modestly sized grid leak resistors. So, low impedance driver circuitry is in order.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.