KPA100 problem

[Luca Valer]

Hello from north Italy.
I have a K2 sn 6822.
With my 1nd KPA100 it's ok (Rev F Oct 2009)
With my 2nd KPA100 (Rev B June 2003) , I have a little problem.

If > 11 WATT work fine.

If < 11 WATT, I have HI CUR on display, for a bit moment, 5 watt on
display is reality abt 15 watt

Need I upgrade my KPA100 ?
Let me konw
Tnx vy 73
in3acv, Luva


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[Don Wilhelm-4]

Luca,

I believe you also have a problem at >11 watts.  If you check the actual
power I believe you will find it is always high (>100 watts) at any
setting of the power control above 11 watts.

The problem is that the power output from the KPA100 is not being
reported to the base K2 microprocessor.  Yes, this also happens at low
power.  The result is that the microprocessor detects no power output
and ramps up the drive to full in an attempt to obtain more power.

The most likely problem source is that the diodes D16 and D17 have been
damaged - probable cause is a lightning (or rain or wind or snow)
static.  The normal recommendation is to remove the antenna when not in
use.  Other possible failure points are U5 and U6 in the KPA100.

If you do find the diodes damaged, it may be a wise step to put a 100
uHy inductor in your antenna system, located near the K2.  Inside an
antenna switch or relay box is one possibility, but lacking that, put
the inductor inside the barrel of a PL-259 connector (one inductor lead
to the center conductor, the other to the shell), then connect that
assembly to the feedline using a coax TEE adapter.  I will not guarantee
that the added inductor will prevent all future diode failures, but it
will reduce the probability of failure.

73,
Don W3FPR

73,
Don W3FPR

Luca Valer wrote:

> Hello from north Italy.
> I have a K2 sn 6822.
> With my 1nd KPA100 it's ok (Rev F Oct 2009)
> With my 2nd KPA100 (Rev B June 2003) , I have a little problem.
>
> If > 11 WATT work fine.
>
> If < 11 WATT, I have HI CUR on display, for a bit moment, 5 watt on
> display is reality abt 15 watt
>
> Need I upgrade my KPA100 ?
> Let me konw
> Tnx vy 73
> in3acv, Luva
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>  

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