[Elecraft] Field repair of blown K3 front end?

[Joe Subich, W4TV]

Randy,

Is the main RX dead all the time (when using only Main RX - Sub RX
off)?

Two quick things to check ...

1) if the Main RX is dead all the time and you have KXV3/A/B boards
    in each rig, swap them.  If the problem moves with the KXV3, the
    problem is most likely D5.

2) If the Main RX works if the Sub RX is off and you have KRX3 in
    in each rig, swap the SUB IN boards.  This eliminates an issue
    with T1 (the splitter) and D1/D2 T/R switch PIN Diodes.

The first thing to check is the KXV3 ... If you don't have a second
KXV3, check the schematics for bypassing the potentially defective
one (J66, pins 13 & 15 and pins 8 & 10).

73,

    ... Joe, W4TV


On 3/12/2016 10:36 AM, Randy Farmer wrote:
> Due to an unlucky combination of station configuration and a bad TX gain
> calibration in my K3s (since corrected) I've managed to burn out
> something in the front end chain in my second station K3. I've verified
> the problem is in the signal path between the ATU inputs and the input
> to the main receiver. The Sub receiver is working correctly when
> connected via the AUX RF input connector, but dead in normal split mode.
> I've had a look at the schematic and can see a couple of probable points
> of failure.
>
> But... I wonder if anyone else has encountered the problem and done a
> successful field repair. I'd have no particular trouble replacing one or
> two parts on the main board, but without a board layout it would take a
> fair amount of effort to find the suspect parts. I'm also not interested
> in completely dismantling the radio if that's what it would take to
> effect the repair.
>
> Has anyone else found and fixed such a problem? I'd be very interested
> in hearing your experience.
>
> 73...
> Randy, W8FN
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