Tony
I have had a iteration via rf with some of my equip. in the past and one sure
way I found was to change frequ. on my transmitter, may need to change little
or allot.
That might explain why the short feed line change made a difference.
One time in particular I was working on a power supply checking vdc and as I
keyed the transmitter the voltage spiked to 40 volts. But as I changed frequ.
the spike was no longer there.
Turned out the ps was ok it was rf giving me a untrue reading.
Jest a thought Happy holidays Buster kg9nd
________________________________
From: Tony <dxdx@optonline.net>
To: towertalk@contesting.com
Sent: Friday, December 23, 2011 1:01 AM
Subject: Re: [TowerTalk] SWR Problem Balun or lightning protection?
Problemsolved?
On 12/22/2011 4:11 PM, Bill Fikis wrote:
> Tony, Any Low Pass filters in the line ?? ........Bill / w2ay
Hi Bill, no filters in line.
Tony
>
> **********************************************************************
> Subject: [TowerTalk] SWR Problem Balun or lightning protection?
> Problemsolved?
>
>
>> All,
>>
>> This has become a real mystery folks. I checked the SWR on my 3 element
>> Steppir today and found that it behaved the SAME as my 5 element 20M
>> mono band Yagi, i.e., the SWR increases after keying down for a few
>> minutes and returns to normal after waiting a few seconds. This happened
>> with all bands on the SteppIR. The antennas are mounted on the same
>> tower about 12ft apart so I always retract the Steppir elements when
>> using the 20M mono bander to avoid interaction.
>>
>> Today, I temporarily "solved" the problem by adding a shorter piece of
>> coax between my rig and amp essentially shortening the total length of
>> coax feeding each antenna by a few feet. I can now key down without any
>> problems and the SWR curves on both antennas have returned to normal.
>>
>> The bad news is that the problem comes back when take the new jumper out
>> of line and connect the rig directly to the separate coax cables that go
>> up the tower to feed each antenna.
>>
>> My guess is that it's unlikely for both antennas to behave the same way
>> because of balun issues or some other problem with the antennas. As for
>> the coax, it's high-end Bury Flex that's a few years old; I carefully
>> soldered and waterproofed the connectors myself. I'm also using the same
>> batch of coax on other antennas and they work fine.
>>
>> The only changes I've made recently was adding 2" copper straps to
>> connect the tower to the ground rods and Polyphaser lightning protection
>> to the rotator and SteppIR control cables.
>>
>> Just to be clear, the SWR issues happen with or without the coax being
>> grounded via the Polyphaser lightning protection; that's either a direct
>> connection between my rig and coax that runs up the tower or with the
>> grounded lightning protection in line.
>>
>> I'm glad all is working fine with the new shorter jumper that changed
>> the overall length of the two coax cables feeding each antenna, but it
>> would seem something is still not right. It's probably a long shot, but
>> I'm going to remove the ground straps from the tower and see if that
>> makes a difference.
>>
>> My sincere thanks to everyone who took the time to reply.
>>
>> Tony, K2MO
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>>
>>
>>
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>>
>>
>> -----
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>> 12/22/11
>>
>
>
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