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
--
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