[Amps] HF-2000 amp problem?

[TexasRF at aol.com]

Sounds like you need to increase the drive to 50-75w like 20m and load  
heavier (less load C) for maximum output.
 
If this scares you, load heavier first and then increase the drive  power.
 
73,
Gerald K5GW
 
In a message dated 4/14/2007 10:25:05 A.M. Central Daylight Time,  
Paul at PaulFerguson.us writes:

I have a  10-year-old QRO HF-2000 amp. It has two Amperex 3-500Z 
tubes. You can see  info on it at: http://www.qrotec.com/

It used to output 1,000 watts or  so on all bands. Now it outputs 
1,000 watts up to 20 meters, but only  about 500 watts on 17 meters 
thru 10 meters.

On 20 meters and  lower, grid current runs about 150 ma and plate 
current about 500 ma.  Plate voltage is about 2,800. Input power runs 
50 - 75 watts. 

On  17 meters and higher, grid current is about 100 - 150 ma and plate 
current  is 250 - 300 ma. A small increase in input power gives a 
large increase in  grid current and little additional output power. 
Input power is 30 - 40  watts.

The amps tuned inputs seem OK as the transceiver sees an SWR of  1.1 - 
1.3.

All measurements were taken using a 50 ohm dummy  load.

Any ideas as to what might be the problem?

73,
Paul -  K5ESW
Raleigh, NC  





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