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
----- Original Message -----
Sent:Sun, 29 Jul 2018 23:57:39 -0700
Subject:[BITX20] Gamma-matching antenna tuner
I am getting interested in a Gamma-Matching antenna tuner (manual one) for suppressing spurious in order to observe Japan’s 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