[Amps] Ten-Tec Centurion Mod. 422 Tubes Look Biased on at Turn on

[James Colville]

Sounds like an intermittently shorted tube. Most likely the grid is shorting to the filament (cathode).

Let us know.
73
Jim W7RY


Sent from Mail for Windows 10

From: n7wbjohn
Sent: Wednesday, July 11, 2018 7:07 AM
To: amps at contesting.com
Subject: [Amps] Ten-Tec Centurion Mod. 422 Tubes Look Biased on at Turn on

In standby at power on, reading the front panel meters

Plate current reads about 50 mA should be zero

Plate voltage about 2400 or 2500V should be 3100

Ig goes negative about 40 mils

Four five minutes amp is trying for space heater status - plates get red
and exhaust is hot.

PPT/VOX to QSK switch no effect.

That was yesterday but today all normal reading and not hot so there's an
intermittent - moved the amp a few feet on a rolling bench was all the
shaking it got and it started behaving.

Where to start? (At turn on, point K on the Filament AC Board did shoot up
to 55 or 60V at turn on then dropped to 34V and there was some Ip but it
zeroed out and all was cool.)

I did look at the archives but I could of missed something.

Tnx de N7WB John
_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps