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Summary: grounding parasitic elements on KT34XA

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Subject: Summary: grounding parasitic elements on KT34XA
From: (Lynn D. Osterbur)
Date: Wed, 9 Oct 1996 20:30:12 -0500 (CDT)

Here is the summary of responses I received regarding grounding parasitic

elemnets on the KT34XA  fyi

curious, Lynn.  Why are the elements insulated from the boom?  73

                              Stu Greene WA2MOE 

                            7537 North 28th Avenue

                          Phoenix, Arizona 85051  USA




>  Now that I have my KT34XA on the ground for the 3rd time, I was thinking

>of grounding the center of the parasitic elemnts to the boom.  The books

>say there will not be any change in performance.  I was wondering about

>static build up.   Anyone have any experience or comments regarding

>grounding or not grounding the reflector and the directors?  

>Thanks    73  Lynn     NO9Z


I asked Mike Staal K6MYC (the inventor) that same question and he said

"leave it like it is."

Would like to hear what you get back from the many experts on towertalk.

Mine is coming down for the third time in 12 years for new caps and the

second balun.  Boy I wish I could find someone with the elements so I could

replace them and fix the old element at my leisure rather than rush to get

them back on.  I do have a crank up and take the elements off one at a time

from my roof.

Dave K4JRB   

Id advise against it, or at least recommend that you document the VSWR

bandwidth and F/B performance of the antenna before and after your

proposed modification to be sure that no unintended degradation has


Multiband Yagis using elements grounded to the boom are subject to

spurious undesired resonances.  This is caused by currents flowing in

adjacent elements and the boom - for example 1/2 half of the last

director, the intervening boom section, and the opposite 1/2 of the

adjacent element.  The "books" you refer to probably referred to monoband

Yagis where such spurious resonances are much less likely.  

I'd don't want to discourage you from trying your idea - but to encourage

you to do so with due attention to detail.




Lynn, I have grounded the end elements on my KT34XA with no change in SWR.

I grounded them at the center via a 2 turn loop of 1/4" copper so they would

act as end loading so the boom could be used as a 40M dipole.  I feed the

boom with a gamma match.  Works very well (>250 on 40 with it.)  GL 73 Clay,

KF4IX (for now.)

curious, Lynn.  Why are the elements insulated from the boom?  73


a postscript...why not ask klm?  73

                              Stu Greene WA2MOE 

                            7537 North 28th Avenue

                          Phoenix, Arizona 85051  USA

You might ask Bruce at KLM    he has been most

Shown 90%, press <SPACE> for more, 'q' to quit, or 'h' for helphelpful to me 
during my resent rebuild. He is THE KT-34 expert.

73s de Ed


Don't even THINK about it....  

"Bad Boy! Bad Boy!"  <whap , whap, whap, - sound of rolled up newspaper>  <g>



Thanks to all who responded......


Now the facts per Bruce at KLM

   Bruce recommends not grounding the parasitic elements unless you are 

   having static build up problems.  He noted that this occurrs most

   frequently along the coast and in very dry areas like Phenoix, AZ.

   In those cases where a popping or crackling noise can be heard on the

   receiver, it is then recommended.  He was of the opinion that the 

   antenna is somewhat quieter with non-grounded elements.  

   I will leave my elements ungrounded, but for those with static problems

   you now have the answer.

   73  Lynn

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