coax in mast

[BOOTY MONSTER]

does the coax running inside the mast , like in the starduster design , have a choking effect on CMC's ?

 

[Robb]

IIRC, it is the coil that chokes out CMC's. The choke coil adds impedance/resistance to CMC flowing back on the coax. The mast will only radiate it again w/o the choke coil.

 

[Marconi]

If you check the old Sigma 4, manual you will see they suggest a similar install. They don't make any other claims in this regard however.

BM, for years I have set my Starduster up using an 8' x 1.25" mast, a 8'4" coax jumper, a barrel connector, and a hose clamp.



I can't tell you for sure it worked as intended, but it seemed to do the job and for sure when I used a little power.

 

[jazzsinger]

If you check the old Sigma 4, manual you will see they suggest a similar install. They don't make any other claims in this regard however.

BM, for years I have set my Starduster up using an 8' x 1.25" mast, a 8'4" coax jumper, a barrel connector, and a hose clamp.

View attachment 8048

I can't tell you for sure it worked as intended, but it seemed to do the job and for sure when I used a little power.

Eddie, I'd be getting some self amalgamating tape or another waterproofing agent on that join, as it is, its a recipe for disaster, once water gets in that coax, its fecked.

 

[W5LZ]

There may be some CMC attenuation but it would only be incidental. I would imagine it would depend on the length of the mast the coax is in. If that length is 'right' it should 'absorb' some of those CMCs, but nothing definite about that. (Sort of like burying coax in dirt?)
- 'Doc

 

[BOOTY MONSTER]

i thought i remembered a thread here where it mentioned there was a choking effect from running coax through a pipe from the feed-point down 9 ft or more ... but i cant find it now . i don't need or plan on doing it ..... just couldn't find the thread to see if i was remembering right .
....... maybe i'm not . LOL . won't be the first time ...

 

[Zman]

I do know the AP needs an unpainted mast to ground to to perform right. But as far as the coax in the mast deal with the SDer i don't think it matters.

 

[Marconi]

Eddie, I'd be getting some self amalgamating tape or another waterproofing agent on that join, as it is, its a recipe for disaster, once water gets in that coax, its fecked.

You're exactly right Jazz, I just didn't want to write a book trying to explain. Your idea is also true for the Starduster feed point, and probably most other CB antenna feed points. I use a non conductive teflon paste inside of my coax connectors that is called "Stuf" and is available at www.aesham.com It seems to work well for me. I check my lines from time to time, and I don't find water problems anymore. Just fill up the connector with Stuf and screw it back together and your good to go.

Water entering into the feed line is probably a greater problem than most ever consider.

 

[Marconi]

I do know the AP needs an unpainted mast to ground to to perform right. But as far as the coax in the mast deal with the SDer i don't think it matters.

Zman IMO, the Starduster is one of the worst case scenarios with water in the feed line. If water can get into the hub it can surely get into the feed line right thru the SO239.