[TenTec] Tuning Amp on 17 meters

[Richards]

Once again, you say what I am driving at better than I can.

I suspect most hams want an easy, quick solution they can wrap their 
heads around.  Impedance, reactance, inductance, capacitance, SWR, 
return loss, and all that jazz is just too blamed complicated for most 
hams, who often lack formal education in physics and electronic theory.

Having high SWR is a known problem and must be dealt with; high SWR 
causes your rig to shut down.   Other aspects are not show-stoppers, so 
hams tend to ignore them.  They don't know whether they have 99% or 39% 
efficiency, but they are on the air and their radios don't shut down any 
more, so they stop and operate.

So I suspect it was an easy fiction to accept - that low SWR means the 
antenna is resonant.  For being so wrong, there is very little 
literature explaining why not.

I suspect most hams do not have the time to become experts on electronic 
theory. It is not their fault, as there are hundreds of valid and silly 
reasons, alike, for this.  They do their best and figure, if they are 
making contacts, then it must be a good antenna.  A "good" antenna is 
merely one that meets one's expectations.  If one makes enough contacts 
to suit him, he has a good antenna; what engineers and physicists might 
say becomes irrelevant.

But SOME hams want more... they want REALLY good antennas, which are 
"good" for good reasons, and that requires a substantial investment in 
learning physics and electronics, and most hams cannot afford to do 
that, or are unwilling to do what it takes, and focus only on what they 
need to know to make it work.  And I am not being critical of anyone in 
this.  It is like playing the guitar... most guys have a little time to 
know a little about a little, and only a few guys ave a lot of time to 
know a lot about a anything.


I passed college physics and learned a little about electricity 30 some 
years ago.  But I still cannot fully wrap my head around all the complex 
measurements we need to know when designing an antenna system.  I am 
working on it, but I have not yet arrived.  I still get confused when my 
analyzer tells me there is 1.2:1 SWR, but only 18 ohms, and 178 ohms 
capacitive reactance, or is that inductive reqactance?... So, sheesh... 
I understand why some guys focus on SWR and decide that equates with 
resonance - it works... their radios no longer shut down and they are 
making contacts.  Why bother with all that MATH ?

My local Elmer Guru guy told me the analyzer does not really tell me 
impedance... and I am still trying to get what he means ... because I 
know he is right and I wanna know.  But until then, I guess I, too, must 
read the analyzer and get on the air when the SWR is low enough.  And I 
will like it a lot better when I figure out what he is talking about!



-----------------  K8JHR  ---------------------

It IS a puzzlement.

------------------  K8JHR  ----------------------

Robert Mcgraw wrote:
>
> What ever happened to using the old fashion Millen Grid Dip Meter or the
> Heathkit Tunner Dipper to find resonance?  I can also use my MFJ 259
> antenna bridge with a 2 turn loop on the input to find the resonant
> frequency.  These do exactly what is needed and thus find the resonant
> frequency of a circuit or antenna.  Then I use the MFJ or Autec bridge to
> adjust the network for 50 ohms thus matching the Z of the resonant
> antenna which is more likely not 50 ohms.  From there regardless of
> length, the 50 ohm feed line is happy as well as the transmitter or
> amplifier feeding the feed line.
>
> All too many times do we hear of hams trimming the antenna for lowest
> SWR.  That simply says they are adjusting the length away from resonance
> to create some reactive component either +j or -j by increasing or
> decreasing the length to make it look like 50 ohms.  Even after doing so,
> they do not have a resonant antenna but they do have a resonant load
> which may or may not radiate well.
>
>______________________________________________



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