[Elecraft] Elecraft K3 problem

[Martin Sole]

Apologies, I just saw the serial number  7818, quite a bit newer so 
maybe not a failed capacitor, yet :)

Martin, H0ZED


On 27/7/63 23:32, Martin Sole wrote:
> Hi,
>
> What Serial number?
>
> I have found on my own and a friends K3, both very low S/N around 300, 
> that the KREF3 board has been the culprit for this exact problem.
> First check the all the TMP cables to and from the KREF3 board and the 
> synths. If all look good you should examine the K3REF board.
>
> In both cases I have found 100nF (0.1uF) capacitors on this board to 
> be essentially a low DC resistance. Look in particular at the 5 volt 
> line. This supply affect IC6 the divide by 6 which provides both the 
> second LO for the receivers and one input to the mixer for the TXIF1. 
> Measure the resistance to ground from either side of L1 and L2 to 
> figure out which capacitor is likely the cause of the problem.
>
> Please keep the list posted on what you find.
>
> Martin, HS0ZED
>
>
>
> On 27/7/63 19:50, LA7NO wrote:
>> Hello,
>>
>> The K3 suddenly stopped working.
>> One day all OK, the next day serious problems.
>>
>> Serial no.: 07818.
>> It has ATU and 100 W PA installed, and also a P3 connected.
>> Both K3 and P3 were earlier well calibrated.
>> Supply: 14,5 VDC.
>>
>> Symptoms:
>> - Rx seriously reduced sensitivity, only strong signals to be heard.
>> - No Tx output. Tuning not successful, no SWR indicated (only the 3
>> hyphens).
>> - Same on all bands.
>> - All displays, controls and menus apparently working normal.
>> - Mic-gain & ALC normal indication on SSB.
>>
>> All menu settings seem to be OK.
>>
>> Connected an XG3 and injected a -73 dBm signal.
>> It showed up on all bands with signal level about -100 dBm, so around 30 dB
>> attenuation.
>>
>> Connected a LP-100A and a 50 ohm dummy load.
>> Whatever we tried, the LP-100A indicated zero power out on all bands.
>> Same on both Ant1 and Ant2.
>> Bypassed the ATU: no change.
>> Set power to < 10 W, effectively bypassing the PA: no change.
>>
>> It is clearly something that is common for both Rx and Tx.
>> It is independent of the selected band.
>> Apparently not related to ATU or PA.
>>
>> So, it could be some relay problem, or related to the SWR bridge or
>> LP-filters.
>>
>> Hope you can give some helpful ideas on how to proceed.
>>
>> Best regards & 73 from Norway,
>>
>> Per-Tore / LA7NO
>>
>>
>>
>>
>> -----
>> 73,
>>
>> Per-Tore / LA7NO
>>
>> --
>> Sent from:http://elecraft.365791.n2.nabble.com/
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>