[TenTec] 160 M antenna

[Bob McGraw - K4TAX]

As you may be likely aware, I did build a tuner, specifically a balanced 
tuner, mostly for 160M and 80/75M and be able to handle legal limit power. 
While it does an excellent job on any frequency less than 18 MHz, I find 
that trying to use it on frequencies above 18MHz is a challenge.

Several factors contribute to such, being physical size of the rollers, the 
leads between components and such.  In fact, after further investigation, 
I've found several resonances above 18 MHz where it will actually "load 
itself" with a short across the output terminals or even another 
configuration with the output terminals not having any connections.  These 
configurations and issues were identified as existing with several 
commercially made tuners recently evaluated by ARRL Lab.

I'd agree that if you intend to work 160M and 80/75M and to some extent 40M, 
one should use a dedicated tuner that is better suited for those 
frequencies.  Then for those bands above 10 MHz a second tuner better suited 
for those would likely be more efficient and less problematic.  I'll likely 
build a smaller tuner using smaller value inductors and smaller capacitor 
value as a Winter project.  My objective is at design to operate 30M -> 6M, 
up to legal limit power with about any wire and feedline combination I so 
choose.

For vertical antennas, I find that a matching network at the base of the 
vertical is best.  In the BC world it is called a "matching network" or 
"tuning unit" and in the ham radio world it is commonly known as an "antenna 
tuner".    Same stuff......different name.     In either case the objective 
is to match the load Z to the feedline Z at the base of the vertical 
radiator.  Thus the feedline is operating at a nominal 50 ohms with a 
minimally reactive load appearing to the transmitter.  If one chooses to 
change bands or even to some extent frequencies, they should have some form 
of variable network being usually required at the base of the vertical 
radiator.

I do have pixs of the current tuner if one so desires.


73
Bob, K4TAX



----- Original Message ----- 
From: "Jim GM" <jim.gmforum at gmail.com>
To: "TenTec-request" <tentec at contesting.com>
Sent: Wednesday, November 06, 2013 1:16 PM
Subject: Re: [TenTec] 160 M antenna


> Rick, I like your answer. I agree with the others too.
>
> Make the external tuner for 160, and 80 and auto tuner, with a remote
> bypass so you can use the tuner in the sack for the other bands. Mount the
> 160/80 tuner out side close to the radial field.
>
> 160M is a pain in the but, to get it working.  BCI messes up my analyzer 
> so
> it is a work in progress and trial and error.  Just too close to the
> transmitter sites.
>
> -- 
> Jim K9TF
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>