[Elecraft] K2/100 Power dither and R98

Bill Coleman aa4lr at arrl.net
Tue Aug 30 19:34:25 EDT 2005


In setting up to use the K2/100 with my newly acquired AL-80A, I  
found that the K2/100 power output 'dithers' about 5-9 watts a few  
seconds after being keyed, depending on the band a power level. This  
makes it difficult to tune the amplifier, as the shifts in power  
output cause changes in Ip, Ig and power out that are unrelated to  
the tuning adjustments.

I found the technical article on adjusting for this by changing the  
value of R98. Rather than go through the complicated procedure, I  
just changed the value of R98 to 1k, then re-checked the power output.

Interestingly, before the change, the output on 10m was about 90  
watts, max. After the change to 1k, it is still about 90 watts.

The amount of dither has decreased quite a bit, but it is still  
evident enough when tuning the amplifier. I wonder if it would be OK  
to try larger values, such as 1.5 or 2 k. What's the limiting factor  
in choosing this resistor?

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901



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