Hi, the KPA100 is alive. I startet to desolder D16 and D17 but D16
broke. D17 was OK. I soldered two new 1N5711 and now after some minor
adjustments the KPA100 is back!
best regards
Holger. DL9HDA
Am 2014-05-05 22:20, schrieb Don Wilhelm:
Holger,
That indicates that D11 is shorted. I would replace D11, D12 and D14
and remeasure.
Do not substitute - use only 1N4007s. While those are normally power
diodes, they work well for switching purposes too, and that is not
true of most other diode types.
73,
Don W3FPR
On 5/5/2014 4:05 PM, dl9...@dl9hda.de wrote:
Dear Don,
thank you very much for your answer. I checked it with an wattmeter
and a dummy load. Nothing.
But I checked the voltages at the diodes especially D11, D12, D13 and
D14 in receive-mode:
D12 and D14 have the right voltages at the anodes and cathodes when I
switch from low-power to high-power and vice-versa.
But the voltages at D11 and D13 are wrong. The voltages at the anodes
and cathodes are always 13,8V. There are no voltages about ~140V. At
D12 and D14 I can measure this high voltages at the cathodes.
best regards
Holger, DL9HDA
Am 2014-05-05 21:55, schrieb Don Wilhelm:
Holger,
Those resistance values indicate that D16 and D17 in the KPA100 are
faulty. The resistance in the forward direction should normally be
much lower. You can check to see if your ohmmeter is reading
properly
by measuring a new or known good small signal diode.
I believe if you check the power output with an external wattmeter
and
connected to a dummy load, you will find a higher than normal power
even though the K2 display and LED Bargraph indicate no power.
You might want to check D1 and D2 in the KAT100 as well.
73,
Don W3FPR
On 5/5/2014 3:09 PM, dl9...@dl9hda.de wrote:
Hi,
my K2 works well but I have issues with my KPA100. KPA100 and KAT100
are both situated in an external enclosure but the KAT100 is
permanently disabled (cal-mode). I used the KPA100 to drive my
tube-amplifier ...
I cannot exactly say what happend but for a year or so the maximum
output power on all bands has been only 60W. It's enough for the
tube-pa but now the output is zero.
If I change the band or hit the antenna-switch the relays are
working. So the communication seems to be OK.
While pressing tune the K2 says high current and there is absolutely
no output-power an the K2 and of course at the KPA100. (The K2
without any connections to the second enclosure works pretty
well!!!).
So the first guess was to check the diodes D16 and D17. I did not
desolder them but I made some measurements with mit Fluke 177.
D16: Diode-Voltage zero and the other direction shows 0.390 V. The
resistor-values are 95.7 KOhms and 104,6 KOhms
D17: Diode-Voltage zero and the other direction shows 0.387 V. The
resistor-values are 95.5 KOhms and 105,2 KOhms
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