[Elecraft] K2 CW tone

[Michael Lawton]

I have completed K2 #4185 to the basic level, and it checks out correctly. However, on-air tests have showed up a very rough T6 or thereabouts CW note. The transmitted TUNE signal is clean, only the keyed signal and memory playbacks are affected. At first I thought it was due to excess ripple on the power supply, but changing to the internal battery made no difference. It's a constant raspy note, not mains hum or (apparently) modulation. 

Baffled.

Any ideas, anyone?

73, Mike GW4IQP