[Elecraft] K2 #3338 intermittent problem

[Steve Ratzlaff]

Hi,
K2 #3338 construction was just going too well--an intermittent problem
on receive has appeared, doing the Part III Receiver Prealignment. First
noticed that the receiver was practically deaf; flexing the coax cable
on the antenna connector caused the receiver to cut in and out. Removing
the heat sink, and putting coax cable from sig gen back onto antenna
connector, flexing the rear of the PCB even slightly causes the
intermittent. (This is the same configuration for a Part II receive
check which was fine, with no intermittent noted then--certainly the
board is flexed then, with no heat sink in place.) Preceding 40m
transmitter alignment (p.72), was normal; only when beginning the
receiver prealignment did the intermittent show up. Have only checked 40
and 80m, but both are affected by the intermittent on receive (have not
tried transmit on 80m).
Initially just tapping on the rear of the PCB with the eraser end of a
pencil caused almost-microphonic-like intermittents. I reheated all the
solder joints on the last ~1.5 inches of the PCB. This didn't change the
intermittent, but now more than just tapping on the board is needed for
the intermittent to show up--it needs to be flexed slightly by hand.
Each solder joint during assembly was inspected prior to cutting the
component lead off. I've inspected both top and bottom again. No relay
leads were cut off after soldering.
Please reply directly (I get the delayed digest mode of the list), if
you have suggestions!
Steve