[GCARC] Elecraft K4 problem

[Robert Pantazes]

I started the CQ WW Phone contest and the 3rd contact told me that my
Transmit audio is breaking up.I switched to a dummy load and started to
monitor my TX audio with a headset, sure enough it was breaking up. I
plugged in the Heil Headset microphone to the same jack on the rear of the
K4 and had the same problem. I cleaned out the jack on the K4 with contact
cleaner and that was not the problem.
I built an adapter for the front jack (8 pin round connector) and plugged
the mic into the front jack, the problem cleared up. I went back to the
contest but I was bothered by this problem.
On Monday I plugged into the rear jack and monitored the break up. If I
turn off the preamp the break up stops. I emailed Elecraft and explained my
situation. Doug at Elecraft answered me and asked for a recording of the
problem, so I emailed a MP3 file. Later that day I received an email to
check for RF leakage. I was transmitting with only 5 watts and did not see
RF on the field strength meter.
The K4 has menus to monitor voltages, I noticed that on TX the input
voltage drops to 10 volts. A BAD power supply! I changed the power supply
and had 13.7 volts at full power and the TX audio sounded great. Why this
happens only on the rear mic input is a mystery for Elecraft to figure out.
I did let Doug know my solution and he thanked me.
That's how I spent my Monday after CQ WW.
One last thought the bad power supply maker will go nameless but they have
3 letters in their name and are out of business from Starkville MS.
73,
Robert "Bob" Pantazes, W2ARP

-- 
A. Robert Pantazes, SBE CBT, Retired Broadcast Engineer from Broadcast
Science.
E-mail address is W2ARP at arrl.net or robert.pantazes at gmail.com
Our new address as of March 1, 2024 is,
5505 Greenlee Road
Greensboro, NC 27410
Cell phone (609) 338-7038
------------------------------------------------------
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