[TowerTalk] TH3MK4 15M SWR fluctuation

George Cortez Jr ne2i at optonline.net
Wed Apr 2 10:45:20 EDT 2014

they are pretty easy to disassemble Use new ss hardware and clean them out. Insects love these traps and make nests in them.

George NE2I

On Apr 2, 2014, at 7:21 AM, Gary Smith <Gary at ka1j.com> wrote:

> I rehabbed my father's old TH3MK4, renewing the electrical contacts, 
> replacing the traps and installing a new DXE-BAL050-H10-A balun. It 
> worked well on all three bands for the last week and its really a 
> pleasure to have access to a beam again as I've only been able to use 
> vertical wires since 1995.
> But last night I noticed the SWR was wildly swinging up to 5:1 on 15M 
> when using the amp and when running barefoot it dropped back to 1.2 
> as it had been at before. More testing finds that anything over 
> 70-80W raises the SWR and it remains stable at 1.2 below that power 
> level. 10 & 20 are unaffected and have a 1.2 SWR. I ran the amp into 
> a separate 15M antenna and there was no issue with SWR so it appears 
> isolated to the TH3.
> I'm suspecting a 15M trap has failed and I either need to replace it 
> or rehab it. I don't know how to tell if it is the driven element 
> trap or one of the parasitic traps that has failed. Deciding which 
> trap is involved is the first problem, my guess is it would be the 
> driven element trap. 
> Once I have that sorted out, are these traps easily reparable & if 
> so, any caveats? I've done a google search but haven't found that 
> answer yet.
> Suggestions on how to determine which trap & how to best rehab it?
> 73,
> Gary
> KA1J
> ---
> This email is free from viruses and malware because avast! Antivirus protection is active.
> http://www.avast.com
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

More information about the TowerTalk mailing list