Topband: Using old 1/2 inch Comscope hardline for my 4-square

[Grant Saviers]

Have you tried an SFX-500 connector?  These are made for 1/2" bare Al 
hardline, 50 ohm but the 75 ohm center conductor should be smaller 
diameter.

With a steppIR beam a broadband match is needed which rules out the 
common coax matching section.  Sevick has designs of transmission line 
transformers for many impedance ratios including 50:75 ohms. Might be 
worth it at the antenna to reduce SWR loss if the feedline is long.  
Almost any tuner will match 75ohms at the amp/rig and most rigs are ok 
with 75 ohm coax swr's.

http://www.amidoncorp.com/transmission-line-transformer-handbook/

Grant KZ1W

On 6/25/2018 22:07 PM, terry burge wrote:
> Hi guys and gals,
>
>
> W9XT came up with a way to connect a PL-259 to a 1/2" hardline. Since I find the Comscope 1/2" hardline I got a whole 4' spool of is not even listed by comscope or any of the manufacturers of hardline I have to try and make a connector. Using his method the toughest part is to 'shrink' the copper clad aluminum or steel center lead. I don't think I can do it. So I'm thinking about using his method modified with 14 gauge wire thru the center conductor of the PL-259 and wrap it around the center conductor on the hardline. Then solder that in. Then use the brass tubing the way W9XT does and solder to the outside of the PL-259 and clamp on the aluminum outside of the hardline shield. THEN try using something like 'liquid Nail' squirted into the inside thru a small hole drilled in the brass tubing to act as insulation and give it some strength. Strength is the biggest problem for using the hardline I think and maybe running up my tower. I don't think it will be strong enough withou
>   t something like the liquid nail and I plan to use a couple of long sections of heat shrink to help. Being in Oregon keeping water out of the connections can be a challenge. But drilling out that center conductor I don't think will work for me.
>
>
> Liquid nail should harden up and I doubt it will have a problem with shorting out the hardline or PL-259. Time may tell another story of course. Various 2 part glues like Loctite or Gorilla glue I don't see a good way of putting them thru the drilled hold in the brass tubing. Anyone know of something else that would come in a squeez type applicator that might do the job and be available locally? Water ingress and making the hardline connection strong I see as the biggest problems. Otherwise I think just using a small plastic or metal box and solder and clamp on wires forming some type of connection to a PL-259 or SO-239 are about the only other alternative I can think of. Of course using 75 ohm coax and having a 'bump' in the impedance will be an interesting challenge to see how that works with my Steppir or other antennas designed for 50 ohms.
>
>
> The hard line does ohm out good so that seemed a good sign. Isn't it fun using cast off coax from cable TV companies?
>
>
> Terry
>
> KI7M
>
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