connectors

[JimmyG]

I've got a question about connecting up an antenna. I'm looking at an Opek UVS 300 antenna, and it has a SO 239 fitting at the base as does the Comet GP 3 antenna that I also am looking at. How do ya'll suggest connecting up the coax to this connector? I've read about different ideas, but would like your input about this, and how some of you accomplished the connection.

 

[camaro1]

put a PL-259 connector on your coax and plug it into the so-239

 

[JimmyG]

OK Camaro1, now I feel really dumb I guess I have been reading to much lately trying to get back into this hobby.

 

[M0GVZ]

Don't worry. Its easy to over-analyse a problem and the obvious solution is only obvious when someone tells you.

You'll get arguments over the best way to fit them but this video should help you on your way.

PL-259 Installation Made Easy for RG8X - YouTube

 

[JimmyG]

thanks, I sometimes tend to over analyse sometimes. I read alot about angle connectors, N connectors, joint tape, etc. Just thought I'd ask what folks are doing when connecting to an antenna.

 

[Mudfoot]

Sorry,

But that video never did cut it. It should be deleted from YouTube. I wouldn't trust any of his connections at all.

 

[W5LZ]

Ther biggest differencein connectors, as such, deal with the inherent losses associated with those connectors at the frequencies of use. While there are differences in the amount of loss in the various types of connectors, the differences are really not that much. In most cases, until it get's into the UHF/SHF regions, those losses are not worth the worry. There are going to be losses with -any- connector no matter what it is. Until those losses get sort of 'big', it's a useless expenditure of worry. If the losses associated with connectors is the determining factor in some particular case, then you aren't gonna hear'em anyway., you know?
- 'Doc

 

[KM3F]

If we really want to get technical, the UHF 259 type hardware is not a 50 ohm connector. The UHF designation is also a misnomer but accepted convention.
The center pin diameter and the outer shell inside diameters and spacing does not compute out to 50 ohms or even close within +/- a few ohms..
So there is an inherent mismatch at that connection point with the hardware.
This is verified in the PASTERNAK catalog as well.
The N and BNC types are very close to 50 as the coax used is close to the same sizes for these connectors.
There is a history how the 259 hardware got to be named as we now know it and adopted as a standard even though it doesn't' really fit, technically..
Good luck.

 

[JimmyG]

This is the type of information that seems to get me into overload as I read and digest it all. Good to know this stuff, but I am afraid I am still to new to be able to put it all together yet. I'll keep studying and one of these days it will make sense.

I used to have a little cartoon that said it all. It was a scientist working on an MRI scanner. There were three snapshots, first one the scientist was looking at the schematics and ingesting the physics of MRI and how it all works, the second caption showed a bright light bulb over his head, the third caption showed the scientist looking confused and kinda down in the dumps looking and it read, "for just a second, it all made perfect sense".

 

[Beetle]

The mismatch of the typical PL-259/SO-239 junction is over such a short distance relative to the wavelength being used that it is negligible for all practical purposes and just a math drill for the more esoteric.

At 10M, the ~2 inches of connector represents about half of one percent of the wavelength. At 2M it's more like 2.5 percent - generally still usable without problems at moderate power levels. Above 2M, the ~2 inches becomes closer to the actual wavelength and problems can pile up.

These were originally called "UHF" connectors because at the time they were developed, 100 MHz was considered UHF.

 

[Road Squawker]

...These were originally called "UHF" connectors ....

Darn,.......... ya beat me to it,......

sometimes I still call them that, and get a strange look from the newer operators,................ and a nod from the older ones

 

[exces3]

UHF conns are perfectly good for 2 meters and down.

my understanding is that a UHF-conn acts like 1 centimeter of
40 ohm coax.. does anyone know for sure?

 

[Captain Kilowatt]

Type UHF connectors are what is referred to as non-constant impedance connectors. This is because their impedance does not remain constant accross the spectrum. They exhibit an impedance of between 30 and 40 ohms for about a centimeter of length which is enough to creat a significant impedance bump in the UHF range.