Best 11 meter radio

Nooo that 75 ohm length comment is not correct..you can have 2 pieces(same length)of 75 ohm coax connected to a pl 259 that connects to radio...

 

Oh yes, you are correct. I guess when J Rich mentioned using a T connector, I was thinking back in the day when I believe Antenna Specialist used the T connector. To make the impedance transformation, they used 1/4 wavelength of 66% velocity factor RG59/U, which was just under 6ft. Then from the T connector to the radio RG58/U coax was used to feed to the radio. My boss is driving an older Kenworth T800, and the co-phased harness in that truck, was like a Y design instead of a T connector. You could pull the coax apart in the middle, because they used the Motorola plug, like the coax on the back of the AM/FM radio in your car.

 

Lol @ a vf of 66..

 

If you use the 73 ohm RG59, the VF is around 66%. If you use the 75 ohm, the VF is closer to 80%.
But earlier we were talking about the 75 ohm coax, so my mistake.

 

Also I made another mistake on my earlier post, about the T connector co-phase antenna system. When you build a co-phase antenna system using 72 to 75 ohm coax, into a 50 ohm coax at the T connector, that’s for base station antennas, not for mobile antennas. Sorry for the confusion.

 

you guys are so confusing and soooooo way off.

OK ... RG-59, RG-6, RG-11 and their variants are ALL ... 75 ohm.

They are not 73 ohm.

They are not 50 ohm, not 63 ohm or 93 ohm - those are actual impedance of other coax cables.

The charts that are created that are on my internet sites are a lot of times wrong, many of them are compiled from different sources and once wrong data is out there, it is out there forever.

the standards were set by the MIL-SPEC MIL-C-17. The RG designation stands for Radio Guide and was used since a little before WW2.

The velocity factor is not just 66, buy vary with insulation type and actual coax model type. Beldon has one VF, while Indiana Wire or Ching have another but it is all supposed to be the same impedance.

 

How about that..... all this time, I thought RG stood for radio grade.

 

Well unless tested before you buy hows a fella to know what the vf is of a coax..
If company specs are wrong,who is right to use as a reference??

 

Craig, a bit of advice and I hope others get this ... IT DOESN'T MATTER.

See this is CB, it is not microwave and as I argued with Rabbi before, the more critical things involved are the antenna and the relationship with the vehicle and the vehicle and its relationship with the ground.

BUT just speaking about the feedline, the VF of a short piece of coax won't make any difference compared to say the coax inherited loss that is not taken in account and I am not speaking of the published coax losses per 100 feet thing but the losses involved with the application itself.

 

I have some RG8X coax I bought a few years ago, and I had no idea what the VF of the coax was. Out of curiosity one day, I used my MFJ 259 analyzer to determine its VF.