[Elecraft] K3 : Unstable output power in DATA A mode

[Keith Onishi]

Output power of my K3/100, SN 79xx, without KAT3 is very unstable in DATA A mode. The symptom is;

1. With setting 100W output on 14MHz and 10MHz, I get 100W output for a couple of seconds, then suddenly the output goes down to 10W or so.
2. On 7MHz and below, the output power never go up to 100W with setting 100W output.
3. With setting around 20W output, actual output sometimes stay around 10W. Upon holding TUNE button a couple of seconds, the output goes up to desired level.

I guessed this might be caused by RF interfere. However, checking with dummy road gave the same results.

These happen only in DATA A mode (I have not tried in AFSK A mode). 
I got stable 100W and a little up in FSK D and PSK D as well as CW. (I have not tried SSB yet.)

I manually made Transmitter Gain calibration without error since K3Utility calibration capability does not work with K3 with 60m disabled for Japan use.

Any thought on this problem?

73 de JH3SIF, Keith