Sounds like no fils or the cut off bias is still up. Check to see if the fils
are drawing current. I usually do this buy putting an ac voltmeter right at the
fils and turn on from a cold start, you should see the filament voltage
increase as the tube warms up. As for the bias, make sure the fuse if there is
one, is good and that your PTT Relay is closing the resistor in series with the
bias.
----- Original Message -----
From: W.F van Wyk<mailto:zs6arf@telkomsa.net>
To: amps@contesting.com<mailto:amps@contesting.com>
Sent: Thursday, April 12, 2007 11:01 AM
Subject: [Amps] 2M 8877 Amplifier: No grid or plate current
Greetings,
I am attempting to commission an 2 meter 8877 home built amplifier.
As I did not do the construction I have to reverse engineer.
The mechanical and electronic construction do look sound and according to
the schematic I have with the amp.
There is about 2,200 Volts on the anode and 4,7 Volts on the filaments.
Problem is with or without drive I get to see not Grid or Plate current on
the meter (which is functioning).
Also I get to see the RF through but when I initiate the AMP the RF through
decreases and no setting will get any response.
Other than the tube being damaged what else can I look for to be the
problem?
Any tests I can do on the tube?
73
Wynand
ZS6ARF
_______________________________________________
Amps mailing list
Amps@contesting.com<mailto:Amps@contesting.com>
http://lists.contesting.com/mailman/listinfo/amps<http://lists.contestingcom/mailman/listinfo/amps>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|