I don't know if it will help you but sometimes seeing a picture or two can
really help out in these situations. I ended up making all kinds of
terminations for some 7/8" CATV line for VHF and UHF several years ago. At
first I was pretty reluctant to try to make up the transformers. It was
designed purely from scratch and formula and they worked just fine. Once I
made a set and played around with them I saw it was really no big deal. Each
set I made after that point kept getting better and better. Years later they
are still in use with perfect SWR.
I can share with you a couple URL's. The first one shows a neat way I was able
to terminate nicely to a N-connector. The copper reducer actually was able to
"tap" its way into the Aluminum jacket perfectly and made a superior fit once I
cleaned it out after running it in and out a few times. The 2nd and 3rd URL's
just show a bunch of pictures I took of the various cables, connectors and
transformers I was working on at the time. Again, maybe seeing some pictures
will help you out. If you have any questions let me know.
http://gedas.cc/view_photo.php?set_albumName=HAM-1&id=catv4
http://tinyurl.com/yspbcr
http://tinyurl.com/23dx7f
73,
Gedas
W8BYA
----- Original Message -----
From: Ethan
To: TowerTalk@contesting.com
Sent: Saturday, February 24, 2007 5:26 AM
Subject: Re: [TowerTalk] re Hardline connectors
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.
<SNIP>
>> 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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