Re: Topband: Fwd: [TowerTalk] Loss in CCS conductors at low freqs (was Voltage Breakdown For Enameled Wire)

[Brian Pease]

My guess is also the steel wires, which have very poor conductivity at 
HF compared to copper.  Aluminum fence wire is also not a good choice 
and would likely literally dissolve if buried, depending on soil 
characteristics.  I use army surface field phone wire, which is a mix of 
copper and steel strands, both wires in parallel for each radial.  The 
insulation makes zero electrical difference with buried radials but 
should preserve the wire for many years.  About $60.00 for 2km on Ebay 
including shipping.


On 1/29/2018 6:48 PM, terry burge wrote:

Hi guys,

I've had two or three different hy-towers in my time and I don't recall any of 
them having this high of SWR on 80/75 mtrs at resonant. Maybe it is the 
galvanized radials from the local farm store (Wilco)?



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Re: Topband: Fwd: [TowerTalk] Loss in CCS conductors at low freqs (was Voltage Breakdown For Enameled Wire)

[Guy Olinger K2AV]

Hi Terry,

What is there about 80 meters that means it doesn't need a carefully done
radial field? If anything, the low bands need "careful" worse...

Your elevated radials will be hard coupled, like transformer windings, to
the buried radials. If a radial and its connections are high R, you will be
coupling that R with the raised radials.

The dip in your SWR telegraphs that the lengths of the HyTower are probably
OK. The R=83 tells us that you have 50 ohms, give or take, of junk
resistance somewhere. Everything all chipper, and you should be seeing
thirty-ish. That could conceivably be a really bad joint connection in the
HyTower, but unlikely as all three joints at the point would have to be
bad. Also the resistance at a point trouble has more effect closer to the
feedpoint.

It also implies you are losing 4.3 dB, something like 2/3 of your power
wasted in ground/radial/connection loss. 940 watts of your 1.5 kW converted
to heat by your antenna system.

With that many radials, a single, or even ten radial problem will not move
the R much. But if ALL the radials are a problem, or the connection point
is bad that could happen.

The first problem you have is that electric fence wire does not worry about
skin effect, or about low resistance for current. It's a high voltage
application. The designed for "signal" is high voltage DC, and low R just
simply does not matter for the intended use.

The second problem is that electric fence wire is NOT designed to be left
laying on the ground or buried. Aluminum can be dissolved by many common
"dirt" compositions when wet. The wire is supposed to be in the open,
supported by insulators, and can dry off after every rainstorm.

On the other hand, for 80 meters, which DOES have skin effect, and in a 1/4
wave vertical which REQUIRES essentially zero R conductors, any kind of
corrosion or typical higher wire resistance, or aluminum connections going
bad, and a long list of problems using fence wire at RF, all can raise your
R. If I had to bet 100 bux on either the HyTower or something related to
the radial wire, it's immediately on something related to the wire. You
probably would have cleaned up corrosion on the joints as you erected the
HyTower.

The absolutely most important part of your HyTower, with nothing in second
place, is the state of the radials underneath and the connections to them.
If any antenna on low bands needs a counterpoise, solve the counterpoise at
maximum efficiency, and insure permanence of that efficiency, before
anything else.

You may hear from here and there that junk wire for radials worked "OK".
Use junk *copper* wire if you want, and solder and corrosion proof all the
connections. What you are looking for is ZERO effective series resistance
at RF from your radial field at the lowest frequency in use, and
construction practices and treatment that insure that it STAYS zero.

In my first house up in New York state, it had aluminum power wiring to the
outlets. The stuff had to be tightened down every couple of years and was a
never-ending source of electrical problems. That was at 60 Hz and no skin
effect. So there's a part of me permanently against aluminum wire unless
you're talking about aluminum tubing, properly treated and fastened at all
the joints.

Good luck, and let us know what you actually find. Theorizing and
speculating on the reflector is one thing, and finding an actual problem
and fixing it is another.  :>))

73, Guy K2AV

On Mon, Jan 29, 2018 at 6:48 PM, terry burge  wrote:

> Hi guys,
>
>
> Even though my main focus is on 80 and 40 mtrs right now I thought I'd
> throw this out to see what other thought. My hy-gain Hy-tower is using 14
> gauge electric fence wire for radials. Most of them are 65 foot or maybe a
> bit longer. About 63 or 64 of them by now. Since it was mainly 80 meters I
> wanted the antenna for I figured the electric fence wire would work just
> fine. Lately  I've even added 4 elevated 12 gauge insulated multi-strand
> copper radials raise about 3-4 feet off the ground. Also one of those 1116d
> RF chokes near the feed point on the LMR-400.
>
>
> I also use the radial system on my 160 meter inv-L over a tree near the
> hy-tower. The 110 feet or so of lengths just goes up and across the top of
> the Oak tree. You can see the pictures of all this on myhttp://
> www.qrz.com/KI7M page FWIW. One of the things that always bothered me
> about this brand new hy-tower is that on 80 mtrs it's lowest SWR point is
> 1.6:1 around 3.785Mhz with an R= 83 ohms and X= 11/13 ohms. I've even added
> the elevated radials and now am up to three 8 foot galvanized ground rods
> trying to get it to dip in more like a 1/4 wavelength antenna of 36 ohms.
> No such luck, that is where it want to sit. I use an old HF6V coil and tap
> it to adjust the resonant point on the 80 mtr stinger.  Other bands are
> similar strange SWR dips for the most part40 mtrs 7.130 Mhz R= 49.2
> ohms  X= 0.0 ohms SWR 1.16/1.13:1;  20 Mts 

Topband: Fwd: [TowerTalk] Loss in CCS conductors at low freqs (was Voltage Breakdown For Enameled Wire)

[terry burge]

Hi guys,


Even though my main focus is on 80 and 40 mtrs right now I thought I'd throw 
this out to see what other thought. My hy-gain Hy-tower is using 14 gauge 
electric fence wire for radials. Most of them are 65 foot or maybe a bit 
longer. About 63 or 64 of them by now. Since it was mainly 80 meters I wanted 
the antenna for I figured the electric fence wire would work just fine. Lately  
I've even added 4 elevated 12 gauge insulated multi-strand copper radials raise 
about 3-4 feet off the ground. Also one of those 1116d RF chokes near the feed 
point on the LMR-400. 


I also use the radial system on my 160 meter inv-L over a tree near the 
hy-tower. The 110 feet or so of lengths just goes up and across the top of the 
Oak tree. You can see the pictures of all this on myhttp://www.qrz.com/KI7M 
page FWIW. One of the things that always bothered me about this brand new 
hy-tower is that on 80 mtrs it's lowest SWR point is 1.6:1 around 3.785Mhz with 
an R= 83 ohms and X= 11/13 ohms. I've even added the elevated radials and now 
am up to three 8 foot galvanized ground rods trying to get it to dip in more 
like a 1/4 wavelength antenna of 36 ohms. No such luck, that is where it want 
to sit. I use an old HF6V coil and tap it to adjust the resonant point on the 
80 mtr stinger.  Other bands are similar strange SWR dips for the most 
part40 mtrs 7.130 Mhz R= 49.2 ohms  X= 0.0 ohms SWR 1.16/1.13:1;  20 Mts 
13.950 Mhz R= 44.1 ohms X= 0.0 or so, SWR 1.22:1;  15 Mtrs 21.300 Mhz R= 34.3 
ohms X=  -14.3 ohms SWR 1.9/1.7:1 (lowest point); no 10 mtrs added. Woul
 d you believe it even works on 12 mtrs being resonant around 24.470 Mhz R- 
50.6 ohm X= -1.0. At  24.930 Mhz it has an SWR of 1.4:1. 


By now I've pretty much figured out that the Hy-Tower uses the 80 mtrs stinger 
for a 3/4 WL 20 mtr antenna so you are stuck with where ever the compromise 
point is there. I've also added the MK-17 17 mtrs stinger (stub, whatever) and 
it dips in pretty good. Way, way down from my Steppir 3 element beam at 118 
foot of course.


I've had two or three different hy-towers in my time and I don't recall any of 
them having this high of SWR on 80/75 mtrs at resonant. Maybe it is the 
galvanized radials from the local farm store (Wilco)?


Terry

KI7M


 Original Message --
From: Dan Maguire
To: towertalk
Date: January 29, 2018 at 2:36 PM
Subject: [TowerTalk] Loss in CCS conductors at low freqs (was Voltage Breakdown 
For Enameled Wire)

Jim Brown wrote:
>>> ,,, but the steel causes losses to increase at lower frequencies as 
>>> compared to copper or silver coated copper.

It just so happens that I've been working with a fellow who has been
measuring loss in Wireman 551 (aka JSC 1318) window line. The
conductors are solid #18 CCS. Using a DG8SAQ VNWA in 1-port mode, he
made sweeps from 0.25 to 30 MHz with the DUT terminated first with an
Open and then with a Short. There was a CMC choke (with
characteristics unknown to me) on the test fixture cable and OSL
calibration was done at the end of that cable using 400 ohms as the
load, not the usual 50 ohm OSL load.

The OC/SC data was then manipulated using a variation on Chipman
equations 7.28 and 7.29 with the following results:

https://postimg.org/image/5mn0wh6bp/

The way I am interpreting the rise in loss at lower frequencies is due
to current flowing in the steel rather than the copper. I would very
much appreciate hearing comments on the shape of that curve from folks
more knowledgeable than me. (Of which there are many!)

BTW, here's a good N6LF article on the subject:

http://rudys.typepad.com/ant/files/antenna_wire_conductor.pdf

Dan, AC6LA
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