[Elecraft] KAT100 Troubleshooting

[Logan Zintsmaster]

Rolf,

If the diodes were blown, there is a possibility that the op amps connected
to them were also blown. In the KAT100 and KPA100 this would be U5 and maybe
U6. U5 provides the FWD and REFL power voltages for the SWR measurement and
U6 provides the RF level signal VRFDET.  If any of these voltages are wrong
"funny" things may happen.  A blown U6 drove me crazy for about a week, so I
am very familiar with this part of the K2.

Hope this helps.
73
Logan, KZ6O
#1609



-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of TWC
Sent: Tuesday, July 15, 2008 7:41 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] KAT100 Troubleshooting

Hi All,


I have my KAT100 & KPA100 in a separate EC2 enclosure. And I have been 
QRP for a while.

The feeder to my dipole antenna on the roof was made of two RG-58 cables 
with BNC connectors.
The connection between these two cables was not properly made since I 
had used ordinary electrical tape
instead of volcanic tape.

However, then the first snow came this year something went very wrong. I 
was using my K2 in PSK31 &
PSK63 mode in about 40 Watts and the KPA100 get warmer than usual It 
became so hot so I could actually
smell it. But no smoke. After I short while when I tried to tune the 
KAT100 it sounded 'funny' and the SWR
leds went a little crazy.

The cable connection was deep in the snow and I have learned from Don, 
W3FPR, to be aware that snow
generated static can cause a large surge on the antenna (just like 
lightning), which can zap the 1N5711 diodes
in the watt meters in the KPA100 and KAT100.  

Three of four 1N5711 in the SWR Bridges were blown. One in the KAT100 
and two in the KAP100. They
are now replaced.

But something is still wrong.

I have tested Relays, Inductors and Capacitors (page 35 in the Manual) 
and all relays are switching.

When tuning in AUTO mode at 10 watts or less the display on the K2 shows 
the power and 1.0 - 1 for all bands
and antennas. When tuning at higher power the display only shows 20 and 
I have to stop the tuning manually.
Sometimes the relays are switching but only SWR led #1 is turned on.

I really need some assistance here!

Best 73's,

Rolf  SMØYQC
K2 #4979
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