[Elecraft] K3/KPA500/KAT500 SWR problem UPDATE

[Tom]

If you are working the bands 30m and below and have the room you can
use inverted V antennas that all have the same feed point.  The power
will be distributed to the the antenna that is resonent at the
transmit frequency.

Until I was able to get room and funds for rotable antennas and
longer wire antennas I used inverted V antennas fed from the same
point.



On Wed, 08 Jan 2014 15:45:48 -0500, you wrote:

>An OCF is an unbalanced antenna and it must have a choke to keep RF off 
>the feed line into the shack.  I use about ten turns of coax on a 4 inch 
>PVC pipe right outside the wall where the feed comes into the house.  It 
>might be more or less, I am not at home to look. You can research it.  
>Other choke baluns would help, if they present a high enough impedance.
>
>That seems to have cured RFI problems for me but I have occasionally 
>felt like I needed more isolation.  Many people have advised me to get 
>rid of the OCF and go with something balanced but it suits my multi-band 
>needs for now.
>
>I am pretty sure RF on the feed line would cause the tuning circuits in 
>the KAT to act crazy.  I'll leave that one for the Elecraft gurus to 
>answer.
>
>Buck
>k4ia
>
>On 1/8/2014 5:57 AM, Ray Coles wrote:
>> As the original poster under this heading I figured you might be interested
>> to know what I have achieved so far, even though I am not yet ready to send
>> the white smoke up the chimney.  Briefly, my problem was that my KAT500
>> would go into uncommanded tunes during a QSO, usually on digital modes.The
>> practical result was that I had to restrict TX power to less than 40Watts on
>> most bands to avoid a burst from the Chicago Piano in the KAT. I had assumed
>> an antenna/feeder problem and had changed every last connector, wire, balun
>> and insulator in my system before asking for help from the Reflector Brains
>> Trust. All of the other people who subsequently reported a similar problem
>> made me feel a little better, and I also received a lot of diagnoses and
>> practical advice which I have followed or will follow soon. One of the
>> simplest was from Ron WB4OOA: Carry out a K3 Gain Calibration via the K3
>> Utility (I had to download the latest Utility version to make this work
>> properly) then Install the KAT500 V1.42 Beta (Not quite as easy as it
>> sounds). After this things were better, and my power setting on the K3
>> always appeared on the KPA500 wattmeter. I could now operate at higher power
>> on some bands but had to stay below 40W on 40m. I had also adjusted the per
>> band retune trigger SWRs upwards via the KAT500 Utility which also helped a
>> little.
>>
>> I remain convinced though, that the basic trigger problem lies with the
>> antenna system (an OCF multiband dipole) and I am continuing to work on this
>> aspect using my analyser. Why it should have suddenly kicked off after many
>> months of solid performance, and why changing everything hasn't yet cured it
>> remains a mystery. My next steps are to try a choke balun on the feeder
>> (parts now to hand) and to prune the antenna to get a better resonance on
>> the bands of interest. Now if only this darn rain would stop! (I still think
>> some tweaking of the KAT500 software might also help!)
>>
>>   
>>
>> Ray Coles, C.Eng. M0XDL
>>
>> 10 Littlemoor Road,
>>
>> Weymouth DT3 6AA
>>
>> Tel: +44 (0) 1305 833699
>>
>> Mob: 07831 516517
>>
>>   
>>
>>   
>>
>>   
>>
>> ______________________________________________________________
>> 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
>
>______________________________________________________________
>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
Amateure Radio Operator N5GE