if I put 2 equal lengths of rg59 together will it be 50 ohms or do I need to add 3 feet of rg58 to the 2 lengths of rg59 to get 50 ohms..i have heard both ways and I dont know of a way to check the ohms thanks
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co phase question
- Thread starter sleepwalker
- Start date
sleepwalker,
If you happen to pick the 'right' length of RG-59 (or RG-11) the parallel impedance will be half of 75 ohms, or around 38-40 ohms give or take a bit (ought to be something close to 1/4 electrical wave length). While that's not going to be 50 ohms it should be close enough not to matter a bunch. Adding 3 feet (or any length of 50 ohm cable) isn't going to make any difference in the impedance at the two 75 ohm cables junction. Depending on what you heard, one version may have been correct.
- 'Doc
If you happen to pick the 'right' length of RG-59 (or RG-11) the parallel impedance will be half of 75 ohms, or around 38-40 ohms give or take a bit (ought to be something close to 1/4 electrical wave length). While that's not going to be 50 ohms it should be close enough not to matter a bunch. Adding 3 feet (or any length of 50 ohm cable) isn't going to make any difference in the impedance at the two 75 ohm cables junction. Depending on what you heard, one version may have been correct.
- 'Doc
I will be using 18 feet of rg59 ...seems everyone has a different take on this...some say the analyzers are junk..others say tune for lowest reflect...I'm confused to say the least :?
sleepwalker,
Well, I guess it justr depends on how well you understand just exactly what an antenna analyzer is and does. Are they always perfect, the 'end all' of tuning an antenna? Of course not, but they certainly do make it easier!
Tune for the lowest (or best) SWR. That's certainly good advice. I don't see anything wrong with that, no matter how you do it. Makes a lot of sense, doesn't it?
The 'best' advice for you, or anyone, is to learn all you can about impedances, antenna matching, etc. You do that by reading, not necessarily listening to someone talk about it (although that's not always a bad idea). How hard is it? Just depends on you. It's not easy, but it's also certainly not impossible.
Have fun...
- 'Doc
Well, I guess it justr depends on how well you understand just exactly what an antenna analyzer is and does. Are they always perfect, the 'end all' of tuning an antenna? Of course not, but they certainly do make it easier!
Tune for the lowest (or best) SWR. That's certainly good advice. I don't see anything wrong with that, no matter how you do it. Makes a lot of sense, doesn't it?
The 'best' advice for you, or anyone, is to learn all you can about impedances, antenna matching, etc. You do that by reading, not necessarily listening to someone talk about it (although that's not always a bad idea). How hard is it? Just depends on you. It's not easy, but it's also certainly not impossible.
Have fun...
- 'Doc
