[TowerTalk] re Hardline connectors

Ethan ethan at ravenscall.net
Sat Feb 24 05:26:11 EST 2007

J. Edward (Ed) Muns wrote:
> I don't know about the original post, but what's written below sounds
> similar to what I do ...
> Parts: UHF F-F barrel adapter, copper pipe reducer and SS hose clamp.  Take
> the barrel adapter and a short section of the hardline (or the exact OD) to
> the plumbing supplies store and find a copper pipe reducer where the small
> end (1/2" as I recall) fits the OD of the barrel adapter and the large end
> (3/4"?) fits the OD of the aluminum tubing on the hardline (not the
> Polyethylene jacket).  Clean the aluminum tubing down to the metal--often
> there is a moisture sealant goo between the Poly jacket and the aluminum.
>> If you're interested in homebrewing your own UHF females for 
>> 3/4" TV hardline, check the Towertalk archives for a message 
>> from W4AN (SK) that explains how to do it with an Amphenol 
>> barrel connector and a $2 plumbing adapter.  For HF, the 
>> half-wave multiple idea worked fine for me here from 160 to 
>> 10 meters, without matching transformers.  I cut the feedline 
>> to be a multiple of a half-wave at 1750 KHz, and then 
>> measured and trimmed the length at 28 MHz.
>> 73, Pete N4ZR>>>

Since this wasn't pointed out very well, 
I thought I should mention it.

Bear in mind that this is 75 ohm smooth 
aluminum CATV hardline, the type
commonly found on poles or buried in 
front of your house, not the 50 ohm
corrugated copper hardline that's 
commonly found on towers.  The
advantage is that it's fairly easy to 
come across this stuff used, and
often for free; also, 75 ohm coax has 
lower loss than the same size 50
ohm because of the greater amount of 
insulation.  The disadvantage is
that in some applications you may need 
impedance matching transformers
to make it work.

Ethan KC8HES

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