Hi Martin;
The RX path goes thru the KPA3 above 12Watts (8W on 6meters).
Look for any burnt parts on the business side of the KPA3.
Check the legs very carefully on the big red coils, they can break yet
still seem good due to the silicone holding them.
Below are some notes;
Keith WE6R K3/K4 Tech
Poor receive RX and NO TX above 12w watts, OK below 12W.
Most likely something on KPA3, like D7,8,9 or 10. Or broken leg on one
of the big red coils.
Or; the relay on the KPAIO3 riser board.
Or; Also peer in thru the fan blades to see if the KPA3 has lifted out
of the sockets.
Or; **On KPA3”A” , rev A thru C, check R5. On Rev D & E, check R19. On
R5, the pads don’t fit the resistors and some earlier resistors only
have solder on the underside at the very ends.
On both; this resistor runs hot and makes the solder underneath crystalline.
Correct part is E500486, 100 ohm 2w ,
HOWEVER, a better fix is; (February 2021-all upgraded KPA3As)
Look for heated resistor and crystalline solder under pads, just gently
pry it, it will pop off if bad;
R5 on Rev C and older,
R19 on rev D and E;
Fix: Remove surface mount 100 ohm, add E500118 100ohm 3 watt leaded as
seen in picture.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
