Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

Arv,

Thanks for your comment.

Yes, as Timothy said, I was completely confused that there would have been a gamma-match manual antenna tuner which could have been placed just after the RF output of rig.

All what I want is a manual antenna tuner which also works as a LPF, that is to say, a pi-match antenna tuner.

BR,

// hiro, JJ1FXF



2018/07/31 3:00、Arv Evans <arvid.evans@...>のメール:

There are a great many articles available on-line for Gama Match Antenna.
Do a Google search for "gamma match antenna" to see what is available. 

Arv  K7HKL
_._

On Mon, Jul 30, 2018 at 2:08 AM Timothy Fidler <engstr@...> wrote:
Hiro,  suggest you look at  ARRL antenna HB . You should be able to find some PDF on line .....copyright breach and all. (this was supposed to be a  PM But what the Heck)

Gamma match generally used only on 2m and above. ONe side of your coax goes directly to the driven ele dipole side A.

Other side goes to  a rod that lines away from the side b but  paralled to  it. THis can be a  solid rod or of the same round stock as the driven element.

There are two PE or PP plastic elements holding the rod away from the B side driven element.  The rod can be slid back and forth along the B element  to get the best possible coupling.

THe exact stand off  distance and rod length  are a black art .  You never try to test or tune up this stuff except at low power or reduced V on finals.

THe coupling into the B side is capacitive and inductive  and distributed.  Hence black art.  It is hellish unlikely you will get this to work with anything other than a Yagi antenna.

Do you have a 1:1 balun in line as in current balun. If you have harmonics in your transmitted signal this will help the issue of return down the outside of your coax  and that will help keep any harmonics forced into the antenna where since they are not resonant , will be somewhat suppressed.   Voltage baluns can be work of the devil and for VHF accept nothing less than type 61 material in the balun core. Above 150 Mhz you cannot even have type 61 because it is getting very lossy but only your tests with a FSMeter will show what the difference is.

cheers New member -
A and B sides are whatever you define them to be - as above.

 

Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2 CB #2885, 
Telephone Whangarei   022  691 8405
e: Engstr@...



----- Original Message -----

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Sent:
Sun, 29 Jul 2018 23:57:39 -0700
Subject:
[BITX20] Gamma-matching antenna tuner


Hi, all.

 

I am getting interested in a Gamma-Matching antenna tuner (manual one) for suppressing spurious in order to observe Japans new spurious regulation.

 

BPF will be fine but I need to make number of coils, right?

 

Then, can anyone point me out where I find some schematics of the Gamma-Matching tuner, or kit of it is very much appreciated.

 

Thanks in advance.

 

// hiro, JJ1FXF

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