I disagree. Of course, I'm running only 1.5kw RTTY output, not 10kw or
more. :)
If you stick with the PIN connectors that are specifically made for your
cable (ie. just having a 3/4 inch connector for 3/4 inch cable is not be
good enough!...make sure it's made for your brand and model ex: Times T10
or Times TX10, or Commscope ?) They arent all exactly the same so make
sure you look up the number in the connector manufacturers catalog to make
sure it's compatible.
Also, as I stated in my previous post, do not use CATV N Connectors. CATV
N's are NOT designed to handle power and they are much smaller (to match
the 75 ohm impedance). I'd still be surprised if someone blew one up
legally, but it's not worth the risk, and they are much more expensive than
my alternative. Use our normal 50 ohm long-body "B" N connector screwed
onto the end of the Pin connector and make sure you use a depth gauge to
get the pin depth correct. If you assemble it correctly and cleanly, I'd
almost guarantee you'd blow up your RG213 jumper before you blow up the
hardline connector. However, if you dont use the coring tool or if you
leave some crud on the center before inserting the connector, all bets are
off.
I've got several of these feedlines in service for over 2 years now with
absolutely no problems, both 3/4 and 7/8" Times T10, both jacketed/flooded
and jacketed/armoured/flooded types. I've got them run 140' underground
direct buried to my current tower and then up to the termination point in
one solid run.
There are a few potential problems with the old copper pipe methods:
1)dissimilar metals corrosion potential, 2) big impedance bumps, 3) high
potential for failure due to unclean installations (nicked center
conductors, shavings from using a saw, poor solder joints if soldered to
center conductor or improperly fitted friction fittings( such as pressed on
UHF barrels), etc.) and probably the highest potential is H2O invasion if
ANY part of your waterproofing is the least bit compromised.
I'm certainly not saying the copper pipe methods dont work, I'm just saying
that your risk factor increases substantially...especially if used outdoors
and your installation methods arent perfect.
73, Tyler K3MM
ai7b@teleport.com on 06/24/97 10:26:07 AM
To: Tyler G Stewart/BENN/CEC, k0wa@southwind.net,
towertalk@contesting.com, pvrc@pagesz.net
cc:
Subject: Re: [TowerTalk] CATV Hardline connectors
i bot/used commercial 75 ohm tv hdline conn's and found that they
are not uoto the job....although they look good they are not designed
to handle power......better/cheaper solution are the home brew jobs made
using brass fittings for 1/2" copper tubing.....
w7gg
----------
> From: tgstewart@pepco.com
> To: k0wa@southwind.net; towertalk@contesting.com; pvrc@pagesz.net
> Subject: Re: [TowerTalk] CATV Hardline connectors
To: <towertalk@contesting.com>
> Date: Tuesday, June 24, 1997 5:51 AM
>
>
>
> The most elegant method is to use CATV connectors slightly modified.
>
> I use CATV Pin connectors with "B-body", 50 ohm N connectors screwed on
the
> end. This is the real deal. This gives you the watertight O-ring seals
> with no soldering except for the center pin of the N connector, which
> solders easily onto the pin. However, this method will move you out of
the
> "free" zone. I'd recommend NOT using the CATV N connectors that are
> available at substantially higher prices. These are 75 ohm connectors
and
> the female socket is much smaller than it's 50 ohm cousin. They are NOT
> compatible and you'll break the female socket if you try and attach a 50
> ohm N male to it. Unless you are using them at UHF or higher, the
> impedance bump will be unimportant, and in those cases you will probably
> want to use the 1/4 wave matching stub type connector to match up with a
50
> ohm termination.
>
> My method requires real CATV Pin connectors, which will probably run you
> anywhere from 7.50 each on up, unless you can find some surplus (I found
> some at Dayton last year for 25 cents each for 3/4 inch line!). The B
body
> N connectors will probably run you 4 or 5 bucks a piece. Lastly you will
> need a "coring tool" made for whatever size of cable you are working
> with... These run anywhere from about $25 to $45 dollars per size. You
> need these to easily and cleanly remove the dielectric from the end of
the
> cable, as the CATV connectors all slip inside the end and clamp onto both
> conductors.
>
> If you want to save money, use this method outside and the old waterpipe
> adapter type inside, where it cant get wet.
>
> BTW, if you have a long run and 2 short pieces of cable, you can buy
> splices from the same suppliers. They arent cheap...generally about
double
> the price of a PIN connector, but it's very sexy, watertight, and
> guaranteed impedance match. It would be the only way to go on UHF and
up.
> On the lower HF freqs you can get a way with a lot of melted dielectric
or
> exposed center conductor without much loss. A lot of guys will just
expose
> the 2 ends and strap them together the same direction, then use a small
> jumper and hose clamps to tie the centers together. I certainly wouldnt
> put this underground, but you could just cover it with a small plastic
> container and tape. Kinda kludgy, but it works...for a while.
>
> BTW, I dont know of anyone making a .86 cable... Times made a .84 cable
in
> their TX10 series. It's real nice stuff with a much thicker shield than
> most so it's hard to kink it, but the connectors are rare and therefor
> pricey...probably close to double the normal ones ($15 to 25 each I'd
> imagine). I've got a bunch of 1.16 TX10 that I'll be burying soon and
> those things were about $25
> each for connectors and $45 for splices! They also were not a stock
> item...it took weeks to get them.
>
> Flooded and/or armoured cables are real nice for burial. They can be
run
> up the tower (I did it), but be prepared for some seepage of the flooding
> compound. It's sticky stuff! However, it cleans up very nicely with a
> citrus-based cleaner and adds some protection if your jacket gets pierced
> somehow... You'll probably have to go back every once in a while and
clean
> up the exposed ends at the connectors, but it's not bad.
>
> Overall CATV cable is a great deal for hams. You should be able to get
it
> for free if you haul it off...especially if you take the reel with you.
> Most of the cable companies end up spending time ie. money taking apart
the
> reels to throw it all in a dumpster (which also costs a lot of money).
If
> you volunteer to haul some of it off, you're almost guaranteed to find as
> much as you want. Initially, I would show up on site and take the reel
> apart there, "throwing" the loose coil into the back of my van and
leaving
> the pieces of reel there, throwing what I could into the dumpster. After
I
> just about crippled myself from trying to load some armoured cable that
> way, I bought a landscaping trailer for that and lots of other uses.
It's
> a 16 footer that'll hold 6 reels and up to 7000 lbs! Now I just roll it
> up the tailgate and strap it in! I've got about 30 reels of cable at my
> place now...some of them with as much as 1500 feet, most of it jacketed,
> and all of it at least 3/4 inch. It's also a much safer way to handle
the
> cable, since it's a lot safer on the reel than off in a loose coil, and
> it'll be a lot easier to uncoil it without risk of kinking, etc.
>
> Loss wise, this stuff is almost as good as equivalent sized 50 ohm
> hardline. Losses are slightly higher due to the smaller center conductor
> of 75 ohm cable, but it's minor. I've yet to use any impedance matching
> transformers. In fact, in some situations it can actually help your
> matching.
>
> Have fun!
>
> 73, Tyler K3MM
>
>
>
>
> k0wa@southwind.net on 06/23/97 11:46:44 PM
>
> To: towertalk@contesting.com
> cc: (bcc: Tyler G Stewart/BENN/CEC)
> Subject: Re: [TowerTalk] CATV Hardline connectors
>
>
>
>
> >Fellow tower talkians,this will be my first attempt at requesting info
> >from Tower Talk.I hope someone can help me.I recently aquired a
> >large amount of CATV hardline.I need to adapt the hardline to standard
> >PL 259 fittings.I have seen articles about this but dont recall
where.Has
> >anyone fabricated any or are there any manufactured that dont cost a
> >bankroll.I will thank you all in advance and look forward to seeing what
> >all the answers to my question might bring me.
> >
> >73 de WT9Q--Bob
> Well, I have seen and read about ever scheme there is to make connectors.
> I
> like the copper plumbing method the best. Using copper pipe fittings,
one
> can make about anything with a drill, a couple of bits, a file and a lot
of
> copper couplers. But...
>
> The most elligant (or maybe I should say crude) method was to just solder
> and clamp pig tails to the cable and have a small amount of regular coax
to
> connect to the antenna or the rig.
> I've also seen where guys have just bent the CATV hardline at 90 degress,
> clamped them together...solder a wire across the center connectors and
> placed a two liter plastic bottle over the whole she-bang.
> Now all you VHFers and UHFers are going have a lot of comments about
that,
> but does it matter on HF? The guys seem to get out and they really don't
> use a connector at all....
>
> Crude, but I dare say it works! We even had to do that on the local VHF
> repeater when lighting blew a hole through one of our quarter wave line
> transformers. We just soldered and clamped on some more coax. The SWR
was
> 1.3 to one and we ran that for three months. Worked fine. I don't thing
> there would be a problem at HF at all. Oh yes....weather proof the hell
> out
> of it with coax-seal, tape, plastic, what have you.
> Lee
> k0wa@southwind.net
>
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>
>
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>
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