Posted by
John Huffman-2 on
Nov 18, 2006; 10:36pm
URL: http://elecraft.85.s1.nabble.com/KPA100-Upgrade-and-KAT100-Problem-tp440984p440986.html
Don -
I have gone from bad to worse. I remelted some solder joints, replaced
the 1n5711 diodes, and re-calibrated the tuner. It seemed to work for a
bit, but problems returned. But now the K2/100 also has problems.
With the KAT100 I tuned the antenna to 80m. It worked OK on QRP, but
with the KPA100 engaged the amp shows high reflected and locks on transmit.
I removed the KAT100 and used a manual tuner. Tunes fine at QRP, but
with the KPA100 on, it is like the K2/100 is on a different frequency.
The tuner setting that was fine in QRP now has high SWR. When I go from
20w to full power, the K2 locks in transmit at full power out. I have
to power it off to quit transmitting.
This same set-up, manual tuner, and antenna have worked fine since it
was setup weeks ago.
With a dummy load on the K2/100 all works well. Tried other cables and
yet another tuner with no success. The K2/100 locks up.
Could I have blown diodes in the KPA100 SWR bridge?
Status - KAT100 has wild LEDs and doesn't like high power.
KPA100 doesn't like 80m and locks in transmit.
73 de K1ESE
John
Don Wilhelm wrote:
> John,
>
> I believe the problem is entirely in your KAT100.
>
> Check all your connecting cables first thing (do a continuity test on both
> the center conductor and shield and check for shorts). It sounds like your
> tuner is operating into an open circuit or a shorted one.
>
> If you have an antenna analyzer, check each cable with it while connected at
> the far end to a dummy load.
>
> After checking the cables, if you still have problems, try re-calibrating
> the wattmeter in the KAT100. Also check the soldering in the KAT100 control
> and wattmeter sections - particularly RP1 and the pins of U3. In fact check
> all the soldering in the KAT100.
>
> Pins 6 and 7 of U3 must go to a low level (to scale the wattmeter readings)
> when high power is active. Check to be certain that is happening and that
> the low level scaling signals are getting to pins 2 and 4 of RP1.
>
> 73,
> Don W3FPR
>
>> -----Original Message-----
>>
>>
>> I had been having problems with my KAT100 and hoped the KPA100 upgrade
>> would help. I installed the upgrade and all works well with an external
>> tuner other than the KAT100. But, the KAT100 problems persist.
>>
>> Here's the problem. The KAT100 tunes fine on all bands into my 50 ohm
>> dummy load if I set the power to 10 watts. But, if I set it to 11
>> watts, engaging the KPA100 build into my K2, the bands 160m through 40m
>> won't tune correctly.
>>
>>
>
>
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