[Elecraft] Transmitting low power through the PA

[hb9brj]

I have recently become interested in the WSPR beacon mode (http://physics.princeton.edu/pulsar/K1JT), which involves transmitting a continuous signal for periods of 2 minutes. At a level of 5W the underside of the K3 gets uncomfortably hot. Since this is the sort of thing you want to leave running all day, I'd prefer the 100W PA with its big heatsink and pair of fans to take most of the strain. Is this possible?


Julian, I'm quite active in WSPR and can confirm that the LPA module is getting hot. When I contacted Elecraft, they sent me a procedure to align several bias currents on the LPA board. To get access, you have to remove the KPA3. I realigned the bias currents but did not notice any significant difference in the temperature of the bottom cover.

As a workaround, you can set PWR to let's say 15W and reduce the LINE IN (MIC) setting.

Playing with PWR and MIC I can reduce my power all the way down to 100mW (measured with an OHR WM-2 QRP wattmeter). And to my surprise my signal was heard 2500km away...

73, Markus
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