[Elecraft] K3/KPA500/KAT500 SWR problem

[Bill Johnson]

Silence doesn't mean there are those of us who haven't had issues with other automatics.  I have had issues using other tuners, MFJ, Etc.  I still use an MFJ 998 external to the shack, and I have some issues with weather; rain, ice and snow with any tuner.  I did get MFJ to replace my first 998 after a yearlong hassle.  The replacement seems to be better. 

Using high power requires lots more care.  I know Dick D. will get some of this fixed for the K-Line in firmware, but the antenna, connectors and common current issues are our problems.  Running troublesome antenna setups can be hazardous at high power.  I have a couple of burned insulators to demonstrate the power of high power RF.  Antenna failure can happen.   I think it best to focus on the Elecraft equipment rather than get into a discussion of other brands as these are not at issue.  
73,
Bill
K9YEQ

-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Richard Solomon
Sent: Tuesday, December 31, 2013 9:05 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3/KPA500/KAT500 SWR problem

What concerns me about all this talk of Reflected Power, local High Power Stations, etc., is that none of the other users of Automatic Antenna Tuners (non-Elecraft) have reported similar problems.

I hope the issue can be corrected via firmware. We will be awaiting the results of their studies.

73 es HNY, Dick, W1KSZ




On 12/31/2013 5:41 AM, Phil & Debbie Salas wrote:
> I haven’t had this problem.  However, in addition to Igor’s thoughts on a high reflected signal, here is another thought.  A strong signal (like you can have in contest environment and/or multi-transmitter/multi-antenna set-up) could be counted by the KAT500 frequency counter resulting in the KAT500 jumping to a different memorized frequency setting.  I don’t know what the threshold sensitivity of the KAT500 counter is, but incoming signals can be very high under some conditions.  I wonder if disabling the internal KAT500 frequency counter might be something to try – especially when band data is provided by the auxbus cable.
>
> Phil – AD5X
>
> “It may be not relevant to this particular case but another reason for weird KAT500 behavior can be strong interfering signal of a neighbor or nearby broadcasting station. I did run into situations where such signals induced up to 5 volts into low band antenna. Then KAT500 counts that signal as reflected and thinks that SWR is very high. One may try to connect broadband spectrum analyzer to the antenna and see what is going on. If it is broadcasting signal well below ham bands then high pass filter between the tuner and antenna can help.73, Igor UA9CDC”
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