Coax shorted inner/outer?

[oceans777]

I have a 67' 14 ga. wire strung up and connected to a Winradio balun 'longwire antenna adapter' Using RG8X from the BNC jack on the balun into the house to the IC-R75.

Yesterday when checking the BNC connector of some new coax connected to the Winradio balun with my Fluke meter, the center conductor and the outer shield of the coax have continuity.
The coax does not have continuity between the sheild and center when disconnected.

The Winradio balun is the source - it has a closed circuit from center to outer of the BNC jack and in fact the center has continuity to the whole outer metal housing of the balun.

I opened the balun up and it appears to have been designed that way.

Shouldn't the outer always be seperate electrically from the inner conductor or is this irrelevant with a single wire type antenna? It seems this would increase noise into the receiver...?

 

[N_Jay]

I have a 67' 14 ga. wire strung up and connected to a Winradio balun 'longwire antenna adapter' Using RG8X from the BNC jack on the balun into the house to the IC-R75.

Yesterday when checking the BNC connector of some new coax connected to the Winradio balun with my Fluke meter, the center conductor and the outer shield of the coax have continuity.
The coax does not have continuity between the sheild and center when disconnected.

The Winradio balun is the source - it has a closed circuit from center to outer of the BNC jack and in fact the center has continuity to the whole outer metal housing of the balun.

I opened the balun up and it appears to have been designed that way.

Shouldn't the outer always be seperate electrically from the inner conductor or is this irrelevant with a single wire type antenna? It seems this would increase noise into the receiver...?

You need to do some studying of transmission line and antenna theory.

If it was designed that way, then it was DESIGNED that way.

Either way, it has NOTHING to do with noise.

 

[oceans777]

Well thanks for the very helpful reply.

 

[N_Jay]

Well thanks for the very helpful reply.

Here is a start.

http://en.wikipedia.org/wiki/Balun

 

[oceans777]

Thanks

Thanks - sorry, I thought you were being snide about your reply. I will read and learn - my attempts to search the web for this didn't find much on why this is ok for this type antenna but I shouldve looked under balun. I understood that it helps match impedance but never knew it shorted the outer to inner.

 

[N_Jay]

Thanks - sorry, I thought you were being snide about your reply. I will read and learn - my attempts to search the web for this didn't find much on why this is ok for this type antenna but I shouldve looked under balun. I understood that it helps match impedance but never knew it shorted the outer to inner.

Well, to tell the truth, I was being snide! (but in a helpful way)

Learning is important!

 

[oceans777]

Yeah it was a ridiculous question - I have been away from shortwave and much of this for years until recently and this was one of those "of course, what was I thinking.." posts.
Great information though and I always appreciate learning. Many excellent wikis availble.

 

[ka3jjz]

Oceans, from our HF antennas wiki, take a look at this. Of course, they're talking about Wellbrook products here, but the concepts might prove useful. Hopefully you have used these concepts in your mounting.

http://www.wellbrook.uk.com/longwire.html

73s Mike

 

[oceans777]

Mike - thats exactly what I was looking for next - grounding and effective isolation, etc. Many thanks!