Belden 8210 72 ohm parallel transmission line - anyone used it?

[N3DRB The Derb]

I'm no longer overly fond of the W7FG stuff and found some of this brand new on the spools, 15 bucks for 100 feet. It's KW 72 Ω parallel line using 13 AWG wire. cant use it for anything but cut to length resonant wire dipoles but thats all I use anyway.

Going to be putting the antenna back up using this stuff instead of teh W7FG. I got 200 ft of it. Anyone ever used it, and if so, how did it work for you?

[K3ZS]

Where did you get it and what name is it listed under?    When I was a poor novice I used zip cord for feedline.    It was suppose to be around 75 ohms.    I fed a 40M dipole with it using a Globe Chief directly.   Didn't know that you shouldn't feed it from an unbalanced source.    It worked great on 40 and 15.

[K1JJ]

That's what we used to call "1 KW transmitting twin lead." Good stuff.

Be sure to treat it just like openwire as far as installation precautions. Keep it away from metal, etc.   Remember how they used to use standoffs for TV twin lead?


Anyway, yes, it is made for resonant antennas and not to be used as low loss openwire with a tuner in mind.  It will have big losses when the swr is high cuz of the dielectric.

This is a situation where I wud use a 1:1 torroidal balun after the transmitter into the twin lead. (unbal > bal)  Get a type 43 core about 2" diameter and wind a 1:1 from the handbook into. Real simple. You will now have a good unbalanced to balanced situation for your balanced feedline and monoband antenna. (Or fan dipole /multiband will work too, as long as its 50-75 ohms design)

You could also use an antenna tuner for the unbal > bal transformation, but that's extra work when a simple, fixed balun will work.  BTW, I know how many guys hate baluns, but in this case, a 1:1 torroidal balun will probably have LESS loss than an antenna tuner, assuming the swr is reasonably below 2.5:1 or so in the twin lead to antenna match.


T

[W2PFY]

I wonder if you would post a picture of that line? As stated above, where do you buy it?

tnx

Terry

[K3ZS]

I couldn't find it anywhere on the internet.     It probably can only be found at hamfests.

[Pete, WA2CWA]

It's not listed as a current Belden product.

[N3DRB The Derb]

http://cgi.ebay.com/Parallel-transmission-antenna-wire-72-ohms-100-feets_W0QQitemZ220457644453QQihZ012QQcategoryZ4672QQcmdZViewItemQQ_trksidZp3286.m7QQ_trkparmsZalgo%3DLVI%26itu%3DUCI%26otn%3D3%26ps%3D5#ht_500wt_956

I got another. I think the guy has a lot more.

[W1JS]

I used it on my 75 meter dipole over 40 years ago when I was still in Mass.  Worked fine.  Still have a couple of lengths hanging around.  Nice heavy guage multi strand conductors and thick insulation.  & worked FB as an AC extension cord when I needed it.   

[k4kyv]

My first antennas when I  first started out as a novice used 72Ω receiving type TV twin lead.  It was about half the size of standard zip cord and the separation between conductors was microscopic.  But it was cheaper than coax and worked well to feed dipoles cut to resonance.  I used it on 80 through 10m, running @ novice power level, and on AM up to 100 watts input once I upgraded.  But when I decided to try higher power, I found the breakdown point to be about 300 watts CW.

The TX stuff should work well even at high power, and I would prefer to use it to feed a dipole than to use coax.  It could be thought of as the modern equivalent of the old rubber insulated twisted pair feedlines used for resonant dipoles before WW2, before the advent of coax.

[Pete, WA2CWA]

Looks like the same stuff we sold at Lafayette back in the 60's and 70's. Also, came in 300 ohm. I checked my printed 2002 catalog and the stuff wasn't in there either.

[AB2EZ]

Fairly high loss stuff. Probably better and simpler to use coax + a common mode choke / line isolator (if you want to minimize feed line radiation).

http://vk1od.net/calc/tl/tllc.php

Belden 8210: 0.7 dB/100ft at 3.885 MHz

Belden 9913: 0.23 dB/100ft at 3.885 MHz

Times LMR 240: 0.5 dB/100ft at 3.885 MHz (similar to RG 8x)

RG58u: 0.85 dB/100 ft at 3.885 MHz

Stu

[Steve - WB3HUZ]

Nice calculator here.

http://www.ocarc.ca/coax.htm

[N3DRB The Derb]

eh, I saw it, knew it could take some power, price was good,  I need some new feedline, I got some. 

into a resonant dipole it will work just ok fine. parallel line with the profile of coax. I like.

one other thing - old buzzard outpoot tank schemes will feed that line directly - no tuner required. stick your line current meters in there and tune for max munky swing.

[K1JJ]

one other thing - old buzzard outpoot tank schemes will feed that line directly - no tuner required. stick your line current meters in there and tune for max munky swing.

Yep, that's the stuff, 1KW 72 ohm twin lead transmission line. Haven't seen any for years.  I remember it for sale at the local ham store in Htfd, CT in the mid 60's.

http://cgi.ebay.com/Parallel-transmission-antenna-wire-72-ohms-100-feets_W0QQitemZ220457644453QQihZ012QQcategoryZ4672QQcmdZViewItemQQ_trksidZp3286.m7QQ_trkparmsZalgo%3DLVI%26itu%3DUCI%26otn%3D3%26ps%3D5#ht_500wt_956


The ad says it uses polyethylene dielectric. I wonder what the loss figures are per 100' ?


I like your idea of feeding it directly with the OB balanced output tank. Simple and effective, OM.

If I were in the market for the stuff, I'd buy all he had - it's like gold amongst older hams.

T

[WA1GFZ]

I suspect this is great feedline as long is the voltage is low. I bet a high VSWR will flash it over.

[N3DRB The Derb]

Well, on a cut to length dipole that shouldn't be a problem. he already shipped the first 2 rolls, got the email notice from Canada Post. 

Never used this stuff before, should be fun.

LB,
I have received the information on the two 70 ohm twinlead products. Both
have been discontinued by Belden for a long time, it would seem.
 
Belden Number 8210
13 awg (7x21awg stranded), .166"x.278", 67%Vp, 21 pf/ft.
Attn: (/100')
100 mhz. - 3.8 db
200 mhz. - 6.0 db
300 mhz. - 7.8 db
400 mhz. - 9.3 db
500 mhz. -11.0 db
700 mhz. - 13.7 db
900 mhz. - 16 db

So what's the loss at 75 meters for 100 ft? maybe 1.1db or so? fine with me.

[Steve - WB3HUZ]

RG213 would be half that loss.

Well, on a cut to length dipole that shouldn't be a problem. he already shipped the first 2 rolls, got the email notice from Canada Post. 

Never used this stuff before, should be fun.

LB,
I have received the information on the two 70 ohm twinlead products. Both
have been discontinued by Belden for a long time, it would seem.
 
Belden Number 8210
13 awg (7x21awg stranded), .166"x.278", 67%Vp, 21 pf/ft.
Attn: (/100')
100 mhz. - 3.8 db
200 mhz. - 6.0 db
300 mhz. - 7.8 db
400 mhz. - 9.3 db
500 mhz. -11.0 db
700 mhz. - 13.7 db
900 mhz. - 16 db

So what's the loss at 75 meters for 100 ft? maybe 1.1db or so? fine with me.

[N3DRB The Derb]

eh Stu posted a calc. I was just guessing.

0.669 dB @ 100 ft @ 3.885.

It'll be ok.

wont make me a mud duck.

[Steve - WB3HUZ]

Ah, much better. Only a few tenths difference compared to RG213. Based on your signal last winter, I think you will be WHIRL WIDE.   

[The Slab Bacon]

Ah, much better. Only a few tenths difference compared to RG213. Based on your signal last winter, I think you will be WHIRL WIDE.   

but now he has to get off of his a$$ and get sumthin makin RF! ! !    

[W2PFY]

Way back on the fifties they had some stuff that looked just like that but was a heavy duty replacement for standard TV twin lead.The OM build a tower that went up 110 feet just so they could get UHF TV over in Logan Run  near Danville, PA were I was raised. Bak den we's wuz so por dat we'ins thought dis is da cat's ass'es. It sure noguf made a big deference holden up in the weather doe. 

 

[Steve - WB3HUZ]

Watz da 411 on my boyz leanyar?

Ah, much better. Only a few tenths difference compared to RG213. Based on your signal last winter, I think you will be WHIRL WIDE.   

but now he has to get off of his a$$ and get sumthin makin RF! ! !    

[K1JJ]

eh Stu posted a calc. I was just guessing.

0.669 dB @ 100 ft @ 3.885.

It'll be ok.

wont make me a mud duck.

I wouldn't expect it to be any better than RG-213 or any quality coax for that matter.  The dielectric is what burns up the power between the conductors. Wire size has little effect unless the impedance is very low, like below 30 ohms or so or the frequency is above ~21 mhz where skin effect can begin to be an issue.  Polyethelene dielectric is no magical insulation, just like any of the many types used in coax.  Of course the best one is air, which is what openwire uses.

Personally, if I had a choice, (and I do) I would use coax cuz it can be run anywhere - on tower legs, on booms, coiled with other coax, etc. Thank goodness for ferrite beads and coax coiled baluns to stop the unbalanced feedline radiation.

That's probably why coax became so popular and twinlead use died off.  But for your OB balanced output tank Derb, the twinlead is a perfect matchup and the simplest solution. Should work FB for your application as long as you keep it isolated like openwire, and don't flash it over, as Frank warned..

BTW, that balanced tank IS capable of low impedance output, right?

T

[The Slab Bacon]

Watz da 411 on my boyz leanyar?

heerz the rub, Bub. If he evah gitz it back ova to me, I'll fix it fer him

[N3DRB The Derb]

If I can hitch a ride from the wifey I'd be there n I could get that transfermer too. I wanna wait until you get the 4X1 going so we can play radio tho. Shes working so much I cant hardly even bum a ride off her anymore.

The Gonset is like a good relationship gone bad. i got so excited getting all my HB stuff together I left it by the wayside.

I need to take a look at it and see where it is - I think it just needs the tube caps hooked up to the plate choke through suppressors & 2 caps installed on the term board.

and of course, someone with enough balls and mad skillz to figure out the ptt wiring....which isnt me anymore. Just dont seem to have the logical ability. Frank could do it in 2 hours.

I'll get something set up or a friday or saturday night soon.

BTW, that balanced tank IS capable of low impedance output, right?

you know it is big brotha. There's no doubt. I kin build it like baskin robbins, 31 flavas of feed, CUM AWN.

pair of 4-400's and you wont notice my lossy twinlead.