Along these lines, you can isolate the K2 from the amp by putting a pad
between them. You can then run the K2 in a more linear range, and
guarantee a good load at all times. I would try 6 dB. Of course,
efficiency will suffer.
Larry N8LP
Don Wilhelm wrote:
Steve,
Remove the KAT2 and the external wattmeter and try the following experiment.
Compare the output variation possible from the K2 when driving a 50 ohm
dummy load with the K2 output developed when driving the amplifier. If you
obtain the same results, blame the K2, but if you find different results,
blame the amplifier. Analyze that data first and correct whatever is wrong.
You may have to swamp the input of the amplifier to obtain a stable 50 ohm
load for the K2. The power control circuitry in the K1 is different than
that used in the K2, so a comparison with the K1 will not provide valid
conclusions - the K2 will seek to provide an RF voltage across the antenna
terminals which matches that required to obtain the requested power into a
50 ohm load. I suspect your amp does not present a constant 50 ohm load to
the K2, and the KAT2 and external wattmeter each may be adding its own piece
of the action too.
With the KAT2 and external wattmeter in line and driving the amplifier,
there are just too many variables to deal with and still draw valid
conclusions - each element may be contributing to the effects you are
seeing. After you narrow things down, you can start adding each piece one
at a time and analyze any changes in behavior due to adding that element.
73,
Don W3FPR
-----Original Message-----
I am trying to use my K2 to drive a little HFPacker amp I built. The
amp needs 2-2.5W input, but I am having trouble setting the K2 output.
For requested levels around 2W, I get 1.5-1.7W as measured by both
internal and external wattmeters and a simple RF voltage probe. This is
into both a good dummy load and the packer using key down and CALP. My
K1 is spot on with output into the amp. When I increase the requested
power to 2.2-2.5 W, power out jumps to 3-3.6W, so I am unable to get 2
to 2.5W. Above and below this range, the requested vs actual output is
fine. I've read most of the archives about requested vs actual power,
but I didn't find anything about too much output at low requested
levels. So before digging into this, I thought someone might have some
ideas about the problem, if it actually is a problem.
Thanks,
73, steve, kx7r
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