[TowerTalk] Fwd: "Antenna Tuner"

Mon May 5 17:17:22 EDT 2014

Yes Dave,

You are right. I just find it "funny" that this relationship exist. Some hams may think that the "reversed" impedance has nothing to do with "tuning".

I just wonder: You, and may with you say that it is most efficient to put the tuner/match box/etc. as close to the antenna as possible. That is true if yoy will get excessive loss due to the high SWR in the feeder between the tuner/match box/etc. Now, if you have a really low loss feeder (like my ladder feed) between the antenna and the tuner/match box/etc. and a maybe higher loss coax (like something really cheap) between the tuner/match box/etc. and the transmitter. You might then be better off (by some silly few fractions of a dB) with the tuner/match box/etc. next to the transmitter.

This is just to make us think a little about that odd situation we normally don't get in to.

Hans -N2JFS

-----Original Message-----
From: David Gilbert <xdavid at cis-broadband.com>
To: towertalk <towertalk at contesting.com>
Sent: Sat, May 3, 2014 11:12 pm
Subject: Re: [TowerTalk] "Antenna Tuner"

With all due respect, that's not a particularly valid distinction.

For example, I can have a non-resonant antenna fed by 100 feet of coax 
(call it Coax A) that presents a reactive load to my transmitter.  I can 
then attach a separate 100 foot length of coax (call it Coax B) to the 
"feedpoint" of the antenna and put some kind of reactive network at the 
other end of Coax B that now results in a matched load to Coax A, and 
therefore to my transmitter.

Or I can use a tuner in the shack to do EXACTLY the same thing ... 100 
feet away from the antenna ... except that I just happen to be coupling 
my power to the same length of coax and network that is providing the 
matching.

There is zero electrical difference between the two situations I 
describe above.  There is zero difference between the transformation 
that a tuner creates and that which a matching network does ... no 
matter where the matching happens to be located.  The ONLY difference is 
that the less transmission line you have between your antenna and the 
matching network the less overall system loss there will probably be.  
That's it ... period.  It is purely semantics what we decide to call the 
various versions of what actually perform the exact same electrical 
function ... there is no difference network-wise.

Dave   AB7E

On 5/3/2014 9:17 AM, WA3GIN in King George, VA wrote:
> Dave, with ipmost and all due respect those mentioned auto-tuners do 
> NOT adjust the resonance of the antenna... they are purely impedance 
> matching devices... some do understand the terminology and the physics 
> ;-)  You can dumb down the tech talk but that doesn't change the fact...K
>
> 73,
> dave
> wa3gin
>
> ----- Original Message ----- From: "David Gilbert" 
> <xdavid at cis-broadband.com>
> To: <towertalk at contesting.com>
> Sent: Saturday, May 03, 2014 11:38 AM
> Subject: Re: [TowerTalk] "Antenna Tuner"
>
>
>>
>> They adjust the resonance of the >system<, and therefore are indeed 
>> "tuners".  It's all the same thing, except of course for the feedline 
>> effects of SWR.
>>
>> That being said, I have never understood why so many hams get hung up 
>> on the semantics of the terminology instead of bothering to 
>> understand what's really going on.
>>
>> Dave   AB7E
>>
>>
>> On 5/3/2014 5:56 AM, Marsh Stewart wrote:
>>> Someone posted the following on the subject of antenna tuners: "They 
>>> aren't
>>> adjusting the resonance of the antenna, so what are they tuning?"
>>>
>>> When I adjust the capacitance and inductance of my "antenna tuner" my
>>> antenna does not change length or height, and the length of the 
>>> feedline
>>> does not change. Could it be because it is not really an "antenna 
>>> tuner" but
>>> is actually an impedance matching network?
>>>
>>> Marsh, KA5M
>>>
>>> _______________________________________________
>>>
>>>
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