Base Gizmotchy SWR Tuning

[edfiero]

Does anyone have suggestions on how to tune the SWR on a Gizmotchy?

I've got a very nice 1.3:1 on CH1 but it jumps up to around 2.1:1 on CH 40. Since I spend all my time on 36 to 40+, I'd rather have the low point tuned to CH40 not to CH1.

I've jacked around with the Gamma length a bit, and moving it will raise and lower the SWR but it doesn't seem to change the fact that CH 1 is always the lowest and CH 40 is the highest

 

[Shadetree Mechanic]

Might need to shorten the elements a bit. Use an online yagi calculator, maybe someone can show us a good one to use.

 

[Blackcat630]

Check all your element measurements and spacing between elements on boom. Were these swr readings taken with an analyzer or trusted meter? Was the beam close to the ground or surrounding structures?

 

[Dmans]

Sounds like the driven element is too long.

73
David

 

[edfiero]

Check all your element measurements and spacing between elements on boom. Were these swr readings taken with an analyzer or trusted meter? Was the beam close to the ground or surrounding structures?

Yes, the antenna is close to the ground. Its just on a 10 mast pole stuck in the ground now. Wanted to try to get it tuned before raising the tower up. Don't have an analyzer but I have used the meter before. No reason to doubt its readings.

 

[M0GVZ]

As it gets lower to the ground below a half wave the resonant frequency will fall due to increased ground losses. When you raise it up you'll probably find the resonant point of the antenna rises 100-200kHz. I always tune dipoles and beams a couple of hundred kHz low when doing it at any height I can reach by hand or with a set of step ladders if the antenna is going to go up another 20-30ft.

 

[midnight special]

back years ago when tuning a beam, we would get it in a clear space with no metal around and point it straight up and tie off with string then tune for lowest swr then put on mast or tower,,,, it worked for what we all was doing back then,,,miss the 70s better time then as compared to now,,,,,

 

[renagade]

i just put up my 5 element and i got the horizontal set at a 1.1 1.2
but on the vertical it will not go no lower then a 1.6 no m atter what i do ive tryed changeing the length of the element and resetting the gamma it just will nnot come down any lower then a 1.6

 

[Staybolt]

Just curious, are tthese beams worth all the hype? 3 locals here have them and I myself, run a 5 element maco. I have a 6 element giz in the garage though and may put it up.

 

[Staybolt]

Hello?