KAT2 not switching antennas after precipitation static event

[ArtLinux]

Initially this KAT2 worked well, switching between ant1 & ant2. During  
a lighthouse portable weekend, in hard driving rain, it may have  
suffered from a precipitation static discharge via the connected  
antenna. Since then, ant2 is always connected. The K-2 (#6155)  
otherwise operates normally.

Believing that relay K18 may have had contacts damaged, it has been  
replaced but with no change in operation.

Operating the switch for ant1 to ant2 results in a relay operation  
sound. Measuring the contacts confirms that the K-18 does not change  
position. The tune function operates normally.

In troubleshooting, the DMM indicates the K-18 coil pin 10 to ant  
connector shell ground reads 208 ohms while the same reading for K-17  
shows 24 ohms.

While tuning the connected antenna: K-18 coil pin 10 to pin 1 reads a  
transient 200 mV and K-17 similar reading is a transient 10 mV. The  
two relay coils measure about 245 ohms each.

Should I assume that U1 is failing to provide the signal to K-18 and  
the relay sound is from another relay possibly also due to U-1 fault?

Your thoughts are appreciated.

Arthur VE9BP


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[Don Wilhelm-4]

Arthur,

I believe you are on the right track in suspecting the firmware.  I
would simply obtain a replacement chip from Elecraft and change it -
that is the only way to be certain unless you have access to a digital
'scope that can record the latching pulses for the latching relays.  It
is very difficult to tell what is going on with an analog 'scope display
since the latching action is a one-time occurrence with each cycle of
the ANT1/2 pushbutton.

73,
Don W3FPR

Arthur Gunn wrote:

> Initially this KAT2 worked well, switching between ant1 & ant2. During
> a lighthouse portable weekend, in hard driving rain, it may have
> suffered from a precipitation static discharge via the connected
> antenna. Since then, ant2 is always connected. The K-2 (#6155)
> otherwise operates normally.
>
> Believing that relay K18 may have had contacts damaged, it has been
> replaced but with no change in operation.
>
> Operating the switch for ant1 to ant2 results in a relay operation
> sound. Measuring the contacts confirms that the K-18 does not change
> position. The tune function operates normally.
>
> In troubleshooting, the DMM indicates the K-18 coil pin 10 to ant
> connector shell ground reads 208 ohms while the same reading for K-17
> shows 24 ohms.
>
> While tuning the connected antenna: K-18 coil pin 10 to pin 1 reads a
> transient 200 mV and K-17 similar reading is a transient 10 mV. The
> two relay coils measure about 245 ohms each.
>
> Should I assume that U1 is failing to provide the signal to K-18 and
> the relay sound is from another relay possibly also due to U-1 fault?
>
> Your thoughts are appreciated.
>
>

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