[Elecraft] KPA100 problem

[Don Wilhelm]

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:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>