When you put the KPA500 into transmit there is some fixed (FET) drain current
regardless of whether you are driving the PA or not. Likewise, the power supply
is supplying this current. So the efficiency is zero and all of this DC power
is converted to heat, not RF. Efficiency increases with drive.
So what you are doing is poor practice. Furthermore, IMD performance of the
driver (K3) is likely better at higher power. It's for sure better at 20W than 10W.
Wes N7WS
On 1/16/2017 7:22 AM, [email protected] wrote:
For the NAQP cw party this past weekend, I ran low power. Rather than
'stress' the K3s with 100W, I chose to run 6W thru KPA500, giving me 100w.
During a one hour run period, 125+ Qs on 15m, I noticed the KPA500 temp
at 51C which surprised me. Idle temp in the shack is generally around 33
to 35C. I expected much lower temp at 100w output.
Why the higher temp and is it not related to power out?
73
Tom
HP1XT
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