Easiest way to check the balun is to hook the feed line to the antenna
without the balun and see if the same thing happens.
Try a different swr meter.
My bet is on a trap heating.
73
Gary K4FMX
Pat Barthelow wrote:
> Keith has it right, below...
> Try this to isolate the problem.
>
> Get a full power dummy load...heathkit cantenna or assorted high power dummy
> loads
>
> Disconnet the coax at the antenna and feed on 15 meters:
> Feed for good long time, taking care to not abuse the transmitter, if it is
> not continuous duty rated.
> 1. first direct to the dummy load
> 2. 2nd via the balun to the dummy load.
>
> Measure SWR during the tests, and you should be able to isolate the problem.
> My bet is on the Balun.
>
> 'best...
> Pat Barthelow aae6g@hotmail.com
>
>
>
>>From: "Keith Dutson" <kjdutson@earthlink.net>
>>Reply-To: keith@dutson.net
>>To: <towertalk@contesting.com>
>>Subject: Re: [TowerTalk] SWR Problem with Tri-Bander - help!
>>Date: Tue, 22 Feb 2005 16:29:30 -0600
>>
>>This symptom is likely heat-related which would explain the variance over
>>time on 500 watts. Simple fact, heat is generated by power that is
>>consumed
>>but not radiated. It could be that this heat is affecting the physical
>>connections to the balun, which of course has the strong likelihood of
>>changing impedance.
>>
>>Keith NM5G
>>
>>-----Original Message-----
>>From: towertalk-bounces@contesting.com
>>[mailto:towertalk-bounces@contesting.com] On Behalf Of RLVZ@aol.com
>>Sent: Tuesday, February 22, 2005 3:11 PM
>>To: towertalk@contesting.com
>>Subject: [TowerTalk] SWR Problem with Tri-Bander - help!
>>
>>Hi Guys,
>>
>>I've got a Hy-Gain TH3-Mark4 that has a rather unusual SWR problem and
>>wonder if you have any thoughts on fixing the problem. Here's the scoop:
>>
>>1) The SWR is always fine on 10 and 20 meters.
>>2) On 15-meters the SWR starts out fine but the longer I transmit the
>>higher
>>it goes. Such as, when running 500 watts the beginning SWR is 1.3 to 1 but
>>after 45 minutes it's 2 to 1.
>>
>>Here's various things I've tried but they didn't fix the problem:
>>1) Replaced the coax.
>>2) Replaced the balun.
>>3) Replaced the 15-meter traps on the driven element.
>>4) Took all traps apart and checked for solid connections.
>>5) Locked the elements together with aluminum screws.
>>
>>This is not my main antenna so it's not a life or death matter. But I
>>really like the antenna and want to correct the problem so I have a working
>>backup and multiplier antenna.
>>
>>Any idears?
>>
>>Thanks! Dick- K9OM
>
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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