I'm looking for some help in troubleshooting an Ameritron AL-811
amplifier (600 watt version) and am hoping someone on the reflector can
help.
I can only seem to get about 200 to 300 watts of output power into a
good 50 ohm load in CW mode. After tuning the amplifier to the
manufacturers specification I increase the drive to the amp and can run
it up to about 300 watts when the output stops increasing. The Ip
stops increasing after getting up to about 300 to 350 mA. The Ig
starts to increase very rapidly at this point.
The plate voltage is resting at about 1500 volts with no drive (a bit
low) and decreases to 1350 volts under the described drive. I have
verified that the line voltage is 120 VAC and only drops to 118 VAC
when the amp is driven. All the diodes in the high voltage circuit
appear to be good (measured using a DVM) in both the forward and
reverse directions.
I have also substituted a different 811 one at a time for each of the
tubes with no difference in the results.
Any suggestions on where to head next?
Thanks,
Mark K2AY
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|