Just wanted to share...

[VE3GZB]

This past weekend I felt that I wanted to put up a 40m inverted Vee in parallel with my 20m dipole. During the winter, I didn't get much radio action what with looking after Yvonne and whatnot, and with only a 20m antenna set up I found that the window of good activity was limited.

So anyway this past weekend I set up a second East-West antenna cut for 40m because I like overseas contacts the best, they look cool on my log sheet.

But I ran out of Coax (or rather the only Coax I had was some aluminum braided RG6 stuff I don't like to use).

Hams in the 30s didn't use Coax, they used whatever they could make. So I didn't make it, but I used a bunch of outdoor 16ga twisted pair speaker wire I had kicking around, and set that up as my feeder to run up the TV mast to feed the inverted Vee.

This evening I worked New Brunswick on it! As long as the antenna tuner can compensate for the impedance mismatch and feed the transmitter something that looks resistive, it seems to work just fine, my SWR is for all intent and purposes 1:1 on 40m just using speaker wire as a feeder line!

I like low budget successes! Anyone can succeed if they throw enough $$$ at a project but to succeed on a low budget, that's FUN!

73s geo VE3GZB

[Steve - K4HX]

Always interesting to see someone try a different twist on thing.   

Just curious as to why you don't like to use RG-6?

[VE3GZB]

I prefer to solder my connections, and it's tough to solder to such a puny little Aluminum braid.

Ironically for the 20m dipole, I used some Home Depot "aircraft cable" and some aluminum crimp-on clamps to keep the tension and everything assembled. For the 20m dipole I am using RG58U and I have the copper from that cable crimped into the aluminum crimp-on clamps. I set that up in the fall of 2009, about 4 months before Yvonne's accident.

This past weekend I pulled that down so I could use the same guy wires to suspend one leg of the inverted Vee. The connections remain good and unchanged by exposure to weather, sun, heat, cold, rain, snow.

My only concern with it at this writing seems to be in windy conditions, the one leg of the inverted Vee and the 20m dipole may come close to each other and I'll see a momentary detuning, reflect by the motion of the SWR meter kept in "reflected" mode.

[Steve - K4HX]

You can solder it.

http://www.ad5x.com/images/Articles/Connectorizing%20RG6.pdf

[Opcom]

twisted speaker wire - that's twisted! I bet it is somewhat lossy, but if it work it works!

[KM1H]

Wonder how long it will take for cheap to become trash? I doubt speaker wire will take severe freezing or UV very well.

[VE3GZB]

Well, it's outdoor-rated speaker wire. The only way to really tell is to leave it out there.

[WD8BIL]

The only way to really tell is to leave it out there.

That's the fun part George.
There's only one way to find out!!

[kg8lb]

 Yep, The price is right but it will likely last longer than first thought. And when the insulation rots you still have the scrap copper !
Costs a lot less than fancy feedline too.

[W3GMS]

A lot of Ham's in the 30's used that feeding method.  Most rigs had link coupled output and the link was simply connected to the feeders.  I believe the term back them was Zip Cord.  No body worried about SWR and the elite hams had an RF ammeter off the link to the feeders.  I am sure the loss was somewhat higher than air spaced open wire line but it worked.  If I remember right, twisted zip cord impedance was pretty close to 70 ohms or so which is good.         

You may consider tuning the 40 meter antenna up on 20 where it looks like 2 half waves in phase and get a small amount of gain.  At the extra height of it compared to your 20 M antenna, the angle of radiation should be somewhat lower and it may be a better when your working DX. 

Fun stuff to play with!

Joe, W3GMS   

[W2PFY]

I believe the term back them was Zip Cord

Awhile back ARRL published an article about using different types of readily available wire for  feeding an antenna. Zip cord had the most loss so much so that it shouldn't be a consideration. 

[W3GMS]

Terry,

And the stuff they used in the 30's was often cloth coated!  I am not sure if rubber was under neath the cloth or not.  Imagine that when it got wet. 

As we all know, when a coax line is mismatched, the loss goes up quite a bit.  When matched the loss is as published in the tables.  Saying that, when the twisted pair is dry and matched, I bet it would not be all that bad.  When mismatched I would expect it to have a much higher loss like a coax line that is mismatched. 

Ok, who wants to run some test on this???  The first step is to measure it characteristic impedance.  Then terminated it with that impedance and see what it looks like...

Joe, W3GMS

[VE3GZB]

Well so far this week, this apparently lossy antenna and transmission line haven't let me down.

I've worked since Monday:

VA3IP, VE9OX, K4KTP, VE3GEN, KR4TI, W4ABF, KF4DWD, WB0KFM, KD8MCE, VA3EGG and NC4TL

Not too bad for such a rotten transmission line!

I'll look at making a few changes this weekend (weather abiding) to the inverted Vee as well as the parallel 20m dipole and see what that brings.

73s geo VE3GZB

[Ralph W3GL]

   The "stuff" that was made in the 30's was called EO-1 cable. 
   It was cloth covered twisted pair, looked like lamp cord.

   RCA made a verson with low loss insulation that had an impedence
   of around 150 ohms.

   The old rubber zip cord was very lossy but the later plastic zip is
   much better at lower RF frequency's.  I've used the #16 cord to
   feed a dipole on 10 meters for field day in the past but it was only
   20 or so feet long: it did work...   

[WD8BIL]

Not too bad for such a rotten transmission line!

AAAAAH! Just ignore the nay-sayers George! There's those on this board that ain't happy until you know all the wrong things about what you did and are more than willing to tell you.

Like the #17 electric fence wire dipole I've had up at the cabin for many years. They told me it wudn't work but I've worked a number of countries including Italy on 160 CW at 5:30 in the afternoon!!!! And you shuda heared them scold me for the wire nut coax connections on it.... whew. You'da thought I turned the laws of radio physics on it ear!

Like I said; once you build it there's only one way to find out ifn it works.
Good job!!!

[VE3GZB]

And you shuda heared them scold me for the wire nut coax connections on it.... whew. You'da thought I turned the laws radio physics on it ear!

For my 20m dipole, I didn't have one continuous piece of RG58. I had two pieces. Guess how I joined them? Yup, a pair of wire nuts and electrical tape to keep the moisture out.

On that 20m dipole last May I worked Denmark, Ukraine, Czech republic and Italy.

Yea, a continuous piece of wire is nice to have. But I'm sure not gonna waste perfectly good pieces of wire just because I don't have one continuous piece of it.

I think I'm gonna have to take the independent 20m dipole down now though. I can't tune it up to save my life. Too close proximity to the 40m inverted Vee is my guess since I could tune it up just fine before, and I don't want to give up 40m now that it works nicely. I don't have too many choices on where I can mount antennae in our back yard, only a clothesline pole and the old TV mast, and the 40m inverted Vee occupies this now too.

I ought to be able to run the inverted Vee as a multiband, but I'm not sure at all what inductance traps I should install, and just where they should be. Does anyone have any experience with two band (40 and 20m) inverted Vee antenna?

73s
geo VE3GZB

[VE3GZB]

What if???

For my inverted Vee, for the radiating elements if I were to use twinlead 300 Ohm, and simply cut one conductor of the twinlead on each side of the Vee for 20m, and the other conductor cut for 40m?

Would this work? Has anyone tried it?

73s
geo VE3GZB

[K1JJ]

What if???

For my inverted Vee, for the radiating elements if I were to use twinlead 300 Ohm, and simply cut one conductor of the twinlead on each side of the Vee for 20m, and the other conductor cut for 40m?

Would this work? Has anyone tried it?

73s
geo VE3GZB

Yes, this will work and is a good solution.  Just alternatively prune each set of legs for the best swr readings. There will be interaction in tuning, so be prepared to go back and forth between bands a few times until they are both good.  This combo-dipole will work on 15M, too, displaying a resonable swr with 50 ohm coax.

T

[VE3GZB]

If for cost reasons I'm forced to choose between 300 Ohm twinlead and, say, 22ga clear speakerwire (the untwisted type), would there be any problems?

I'd imagine the 300 Ohm twinlead would have a lower capacitance between wires than speaker cable, but would this be anything to really worry about?

73s
geo

[K1JJ]

Much would depend on power level and the impedance at any given point. Hard to say. But I would opt for the twin lead for higher voltage rating since you have a choice.  The point of arcing would likely be in the general area at the end of the 20M legs to the 40M legs.

Be sure to mechanically reinforce the 20M cut point so the wire strength is not compromised on the whole 40M span..

T 

[VE3GZB]

Hmmm, looking into it now, it seems that nobody in my area carries 300 Ohm twinlead anymore, not even a ham radio shop 3 hours from me carries it.

[W2PFY]

geo, How many feet do you need? I think if you took your zip cord and separated it into two pieces and then make something for spreaders, you would be ok. Perhaps clothes pins would work until you found something better.

[VE3GZB]

Well, I gotta think about appearance. The antenna would be quite visible to neighbours and to my wife, and neither would appreciate that. In fact they'd ask me to take it down or do something to make it look invisible right away.

Currently I'm using some thin copper wire which is virtually invisible. And I know that light/transparent coloured 300 Ohm twinlead was made in the past, so the asthetic aspect appeals to me to be able to keep the antenna up and not earn complaints.

73s
geo

[K1JJ]

.

[W2PFY]

Well I have some 300 ohm wire but it's dark in color, maybe black, so I guess that will not work?