peddler, do you know the magic feed length multiples?
so is it an odd multiple of 18 feet or what? I only ask because i'm in trouble myself. I blew the finals in a 3 week old 2970n2 on a 3 yr old antron 99 with 20 metres of westflex 103 with SWR's at 1.5 at the end of the coax and SWR's at the antenna of 1.2. I had heard of mosfets giving trouble with high swr's so I wasn't suprised.
But what really maddened me was how another install worked.
A neighbour was getting in to cb so he begged a sigma venom aluminium homebase antenna off a relative and couldn't tune it.
(and from what I have read 1/2 wave aerials don't work without a balun and only 1/4 wave and odd multiples of that work like 3/4 wave and 5/4 wave etc so I didn't know how it would work)
I couldn't either no matter whether the antenna was shortened or lengthened feet or inches the swr allways stayed just over 3
I had heard that they didn't work without being mounted on a metal mast(he had it screwed to a timber post) so I hung 3 104 inch radials at 45 degrees from it , no change in swr
Then I opened the antenna and clipped the shorting coil , no change in swr
Then I shortened the mast to 102 inches(from more than twice that) and perfect 1.0 flat swr on high low and mids and 20 feet of rg58.
Im convinced that aerials with a short like the A99 are at fault and cause varying swr on the coax as he just guessed the coax length and setting the aerial up like a 1/4 wave worked better than I could imagine.
(with no fudge tuning)
I can't understand why a brand new a99 could never operate right as before I bought the ranger when I had 170 feet of 75ohm thicknet it had the very same swr as the ideal cable run and yet the roughest antenna install I have ever seen worked perfectly?
You see 18 feet is too short for me as I need a run longer than 20 metres so what run should I use
So please nobody tell me that coax length doesn't matter as I just blew up a box because of it.
so is it an odd multiple of 18 feet or what? I only ask because i'm in trouble myself. I blew the finals in a 3 week old 2970n2 on a 3 yr old antron 99 with 20 metres of westflex 103 with SWR's at 1.5 at the end of the coax and SWR's at the antenna of 1.2. I had heard of mosfets giving trouble with high swr's so I wasn't suprised.
But what really maddened me was how another install worked.
A neighbour was getting in to cb so he begged a sigma venom aluminium homebase antenna off a relative and couldn't tune it.
(and from what I have read 1/2 wave aerials don't work without a balun and only 1/4 wave and odd multiples of that work like 3/4 wave and 5/4 wave etc so I didn't know how it would work)
I couldn't either no matter whether the antenna was shortened or lengthened feet or inches the swr allways stayed just over 3
I had heard that they didn't work without being mounted on a metal mast(he had it screwed to a timber post) so I hung 3 104 inch radials at 45 degrees from it , no change in swr
Then I opened the antenna and clipped the shorting coil , no change in swr
Then I shortened the mast to 102 inches(from more than twice that) and perfect 1.0 flat swr on high low and mids and 20 feet of rg58.
Im convinced that aerials with a short like the A99 are at fault and cause varying swr on the coax as he just guessed the coax length and setting the aerial up like a 1/4 wave worked better than I could imagine.
(with no fudge tuning)
I can't understand why a brand new a99 could never operate right as before I bought the ranger when I had 170 feet of 75ohm thicknet it had the very same swr as the ideal cable run and yet the roughest antenna install I have ever seen worked perfectly?
You see 18 feet is too short for me as I need a run longer than 20 metres so what run should I use
So please nobody tell me that coax length doesn't matter as I just blew up a box because of it.