Seems to me the original poster mentioned SWR @ frequencies of interest.
The assumption made there is that "lowest SWR = resonance".
When measuring at the shack end, that lowest SWR will indicate when the
SWR-measuring device sees an impedance closest to ITS characteristic
impedance. This has nothing to do with "resonance" of the antenna, but,
rather, that assumption above.
Last time I was up at 80+ feet on my old tower, I was able to measure
the resonant frequency of my yagi[s] by utilizing a GDO and frequency
meter. Then I connected the feedline[s] and shot DX.
As you may be aware, the 'lowest SWR' at the shack end of a random
length of coax will only give a relative measure of how the antenna and
feedline match the characteristic impedance of the SWR meter/device.
Don
N8DE
Keith Dutson wrote:
> Is it resonance that changes? I thought it was impedance.
>
> 73, Keith NM5G
>
> -----Original Message-----
> From: Don Havlicek [mailto:n8de@thepoint.net]
> Sent: Friday, September 01, 2006 1:33 PM
> To: Keith Dutson
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] C31 - 1 feed line or 3
>
> When measuring the 'resonance' of an antenna at the shack, you are NOT
> measuring the antenna's resonance .. you are measuring the resonance of the
> antenna and feedline.
> Remember .. the feedline SHOULD have NO effect, but it will, unless it is an
> exact 1/2-wavelength multiple at the particular frequency at which you are
> making measurements.
> Don
> N8DE
>
> Keith Dutson wrote:
>
>>What changes the resonance at the shack?
>>
>>73, Keith NM5G
>>
>>-----Original Message-----
>>From: towertalk-bounces@contesting.com
>>[mailto:towertalk-bounces@contesting.com] On Behalf Of Don Havlicek
>>Sent: Thursday, August 31, 2006 10:24 PM
>>To: N2TK, Tony
>>Cc: 'Ron Feutz'; towertalk@contesting.com
>>Subject: Re: [TowerTalk] C31 - 1 feed line or 3
>>
>>Where did you make those measurements?
>>
>>If at the shack end of the coax, they are quite meaningless as to
>>antenna resonance.
>>
>>The only way to get the correct measurements is AT THE ANTENNA.
>>
>>Sorry, but too many guys/gals put their SWR meters at the shack end of
>>the coax and try to determine what the ANTENNA looks like from there.
>>
>>It just doesn't work that way.
>>
>>Don
>>N8DE
>>
>>N2TK, Tony wrote:
>>
>>
>>>Ron,
>>>Mine resonates at
>>>
>>>28.64 - 1.1:1
>>>21.22 - 1.25:1
>>>14.1 - 1.2:1
>>>
>>>Single feed.
>>>
>>>N2TK, Tony
>>>
>>>
>>>-----Original Message-----
>>>From: towertalk-bounces@contesting.com
>>>[mailto:towertalk-bounces@contesting.com]On Behalf Of Ron Feutz
>>>Sent: Friday, September 01, 2006 10:02 AM
>>>To: towertalk@contesting.com
>>>Subject: [TowerTalk] C31 - 1 feed line or 3
>>>
>>>TT'ers,
>>>
>>>I just ordered an F12 C31XR. I have been told by experienced users
>>>that the beam can be a pain to tune properly on 15 (high swr).
>>>
>>>I ordered the beam with single feed. Since then I have heard that the
>>>problem is less severe with the 3 feedline model.
>>>
>>>All inputs from experienced users will be welcomed.
>>>
>>>Thanks and 73,
>>>
>>>Ron KK9K
>>>
>>>_______________________________________________
>>>
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>>
>>
>>
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