Bob,
Great work.
The EL5146 can be ordered from Elecraft, and if it has been discontinued
in the DIP package, the SMD equivalent will be supplied mounted on a
carrier board to adapt it for thru-hole use.
If you have the K60XV installed in your K2, the use of a non tri-state
op amp will interfere with the K60XV transceiver output power control.
I really don't know the cause of these failures, I just don't have
enough information about the circumstances of operation when the failure
takes place. I have seen a few of them, but it is a small percentage -
you were one of the unlucky ones.
73,
Don W3FPR
Bob G3PJT wrote:
Hi Don
I was just about to send something to the reflector. Both the 1406 and
the 5146 had failed but I do not know why.
However the solution was :-
- find out which chip was crowbarring the 5v line. Pull the PIC - it
was OK in my case. Cut pin 16 on the 1406, check and resolder if OK
(it was OK in my case) Do the same with pin 7 of the EL5146 which
showed that it was that chip which had failed. Extract the 5146 by
cutting the pins and clean up the board with desoldering tape.
Sacrifice the chip not the PCB. Replace with a 8 pin socket as EL5146
is discontinued here. Use almost any op amp with the same pinout
except for pin 8 and clip off pin 8.
- I determined which channels of the 1406 were not working using a
prototype board type interface and then rewired the 1406 to use the
unused 232/TTL interfaces, only the pin5/12 circuit had failed in my case
- replace the 78L05 as its not clear how much abuse it had suffered.
73 Bob G3PJT
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