[Elecraft] KAT100 Problem

[Dale Putnam]

I'm wondering, kinda thinking in the blind, if there might be a coil not making contact, either a lead at the solder point, or a relay contact not good any more..???
Have a great day, 
Dale - WC7S

-----Original Message-----
From: richardjwiltgen at aol.com
Date: Mon, 8 Jul 2013 00:09:05 
To: <don at w3fpr.com>
Cc: <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] KAT100 Problem



 Don,
 
 Thanks for your prompt response.  Yes, I reduced everything to its bare minimum and tested it on a dry dummy load.  I am sorry; I should have stated that.  I also used about different jumper cables to connect to the dummy load, all yielding the same results on both 20 and 40. I also tested 10 and 80. It went off scale with much sooner on 10 meters as I progressed through the capacitors, but there didn't seem to be any dramatic change on 80.  The results with the dummy load almost precisely mirror those experienced with the antenna on 20 meters.  I was just using it with the antenna on 30 and 17 with excellent results.  It loads the antenna beautifully on all bands 10 through 160, with the exception of 20.  I will check the capacitors again on 30 meters later this evening.  Unfortunately, I do not have a capacity meter.  I am in Florida with the bare minimum of test equipment and scheduled to follow the snow birds north this week.  i'lllet you know what results I find on 30 me
  ters.
 
 73,
 
 Dick
 
 
 
 
 
 -----Original Message-----
 From: Don Wilhelm <w3fpr at embarqmail.com>
 To: richardjwiltgen <richardjwiltgen at aol.com>
 Cc: elecraft <elecraft at mailman.qth.net>
 Sent: Sun, Jul 7, 2013 7:45 pm
 Subject: Re: [Elecraft] KAT100 Problem
 
 
 Dick,
 
 Are you doing the component tests (C5 to C6 for example) into a dummy 
 load or into your antenna.
 Trying that test into an antenna just adds a lot of other unknowns into 
 the formula - use a dummy load.
 Not only that, check the dummy load and the coax going to it - if you 
 have an antenna analyzer, put it on the end of the coax that you are 
 connecting to the KAT100 and see what the impedance is - it should be 50 
 ohms resistive and zero ohms reactive (or very close). Bad coax is a 
 frequently overlooked problem spot as are PL-259 connectors that are not 
 fully tightened.
 
 In other words, reduce the system to its bare essentials when doing any 
 tests.
 With the known good dummy load and coax, now try the manual instructions 
 again.
 If you get the same results on 20 meters, drop down to 40 meters and try 
 the same test.  Often the switch between one capacitor and another will 
 cause the SWR to 'go offscale' on a higher frequency, but be just fine 
 at a lower frequency.
 The jump in capacity between C5 and C6 is quite large - C5 is 150 pF 
 while C6 is 300 pF, and that is a LOT on 20 meters.  Your results when 
 dropping down to 40 meters seem to be in line with reality.
 
 There is an alternative test (not in the manual) that you can do if you 
 have a capacity meter.  Connect the capacity meter between the center 
 conductor and the shell of the input jack.  With C0 selected, zero the 
 meter (or record the stray capacitance shown), then cycle through the C1 
 thru C8.  The capacitance should approximately double with each step 
 upward in Cx.  If you are not using a capacity meter that has a zero 
 capability, subtract the capacitance measured at C0 from the reading at 
 the other capacitors to arrive at the real capacitance value that the 
 KAT100 is connecting.
 
 Yes, your RF-in-the-shack can be confusing things a lot.
 
 73,
 Don W3FPR
 
 On 7/7/2013 7:06 PM, richardjwiltgen at aol.com wrote:
 > I have encountered difficulty with the KAT100.  I am pretty sure the problem 
 resulted from RF feedback in the shack from a Zero-Five flagpole antenna with an 
 unun at its base, an ugly balun with Polyphaser ground after 80 feet of coax 
 prior to entry into the shack, and a Balun Designs isolation balun following the 
 20 feet or so of coax that enters the shack.  The isolation balun is inside the 
 shack for stealth reasons because of a very intrusive HOA.  Thae KAT100 would 
 not tune the antenna or a dry dummy load on 20 meters. It will indicate a high 
 SWR and the K2 registers a hot power amplifier. If I run it for a while, the RF 
 gets into the radio and the other bands may be affected.  As a consequence, I 
 will eventually move the isolation balun between the KAT100 and the K2/100 and 
 place another one on the line that leads into the shack.  I tested the 
 components as stipulated in the manual.  When I switch from C5 to C6, the SWR 
 jumps from 2.5 to off scale (9.9) on 20 meters and
 >   1.4 to 7.0 on  40 meters.  Based on the knowledge and past experience of 
 others,  does it seem reasonable to assume that C6 is defective and the cause of 
 the problem?  Many thanks beforehand for any advice you folks have to offer.  Vy 
 73, Dick, K8RBW.
 >
 
 
 
  
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