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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