Open Wire for Low Loss ?
rossi at VFL.Paramax.COM
rossi at VFL.Paramax.COM
Tue Aug 23 10:44:24 EDT 1994
Years ago I used a 150' run of open wire line on 2 meters and it worked
pretty good ... until it got wet. All of the signals would disappear every
time it rained. This may not be as much of a problem on HF as VHF but I am
sure there would be some increase in loss when everything is wet.
Pete Rossi - WA3NNA
rossi at vfl.paramax.com
Unisys Corporation - Government Systems Group
Valley Forge Engineering Center - Paoli, Pennsylvania
>From Kurszewski Chad" <kurszewski_chad at macmail1.csg.mot.com Tue Aug 23 09:47:55 1994
From: Kurszewski Chad" <kurszewski_chad at macmail1.csg.mot.com (Kurszewski Chad)
Date: 23 Aug 1994 08:47:55 U
Subject: NAQP Observations
Message-ID: <199408231347.AA08527 at pobox.mot.com>
>After your comment yesterday about the 100 watt power limit, I made it
>a point to check QST last night to make sure, because my recollection
>was that it was 150 watts. Well, sure enough, in the July QST contest
>column, the announcement for the NAQP stated 150 watts maximum output
>power. What was your source for the 100 watt figure, I wonder?
>
>Alan, K6XO
My source of the 100 Watt figure was NCJ itself in the 'Official Rules' of the
NAQPs. Normally it is in January/Feburary's issue, but I think this time it
was in Nov/Dec issue of 1993. It was one of those issues and it definitely
said 100 Watts.
p.s. I commented about owners/users of FT-1000s and IC-765s having to turn down
the power. What I meant was IC-781 users, and also TS-950s and anyone else who
tweaked their PA in their exciter.
Chad WE9V
>From fish at crl.com (Bill Fisher, KM9P Concentric Systems, Inc.) Tue Aug 23 15:18:12 1994
From: fish at crl.com (Bill Fisher, KM9P Concentric Systems, Inc.) (Bill Fisher, KM9P Concentric Systems, Inc.)
Date: Tue, 23 Aug 1994 07:18:12 -0700
Subject: Radials/Shunt Feed Review
Message-ID: <199408231418.AA04084 at mail.crl.com>
Well, I didn't want to post this to the entire reflector because of the
size, but I have received over 100 requests for it. Since that is about 1/3
of the reflector anyway... Here it is!
>From W0UN
Shunt feeding info was by Gary Breed K9AY and appeared in the Low Band
MONITOR ed. by K0CS jsut to keep the record straight. Gary's piece will help
clear up a lot of the mysteries why
shunt feeding sometimes works and sometimes not.
Just a few quick comments on verts and radials.
1) Radials on the ground are not resonant so there is no magic length.
2) For a 1/4 wave vert the currents in the radials are concentrated
near the base of the vert, so if you have a fixed amount of wire it
is better to have more short radials than a few long ones.
3) Electric fench wire (steel) is a relatively poor conductor since the
currents are flowing in the zinc coating due to skin effect. And
it deteriorates very rapidly when in contact with the ground.
Electric fence wire (aluminum) is harder to find but conducts well
for its very short life. It corrodes very rapidly when in contact
with the ground.
4) Use copper wire, either bare or insulated. With a lot of radials the
size isn't that critical since the current divides between the
radials. Insulated wire of relatively small diameter will probably
last longer than small diameter bare wire. The copper doesn't
corrode as fast as other metals, but for small diameters the
insulation will delay things for quite a while.
5) I recommend a minimum of 60 radials a 1/4 wave long if you want
really good performance. Less and shorter will work but performance
drops off relatively quickly. 60 by 1/4 wave is a pretty good
compromise between labor, dollars, and performance. But to go
all out do something with 120 radials that are 3/8 to 1/2 wave
long.
6) Burying them is the hardest part. A number of little plow blade
arrangements with a tube welded down the back end of the blade
to feed the wire into the slit in the ground have been used. A
small one can be made and pulled with a riding lawnmower if the
depth of the slit isn't too great and there aren't too many rocks
or roots in the way. Burial depth does not appear to be critical
since the depth of penetration at the low HF and MF frequencies
is quite great.
7) Reconsider elevated radials. It only takes four!
K0CS just installed 4 elevated radials on a 160 meter bent 1/4 wave wire
vertical antenna, resonating them as I mentioned during my talk last year
at Dayton and he has had excellent performance while running only 500 watts.
He has made 21 VK/ZL contacts on PHONE on 160 during the period of 3 Aug to
12 Aug. Working the 7000-8000 mile path on every night except Aug 7 when
there was high QRN. The radials are about 10 ft in the air and each pair
on a straight line is fed like a dipole and tuned to resonance by grid
dipping it to compensate for the detuning from the ground before connecting
it to the coax shield. He tried a number of different combinations of
elevated and ground mounted radials and made numerous field strength
measurements at 45 degree intervals around the antenna and the elevated
system really performed.
There have been a couple of comments about resonant 1/4 wave radials being
bad due to stored energy (?) and therefore higher losses and due to the
rapid reactance change at resonance, but all of these comments appear to
be "old wives tales". Steve is certainly pleased with the performance
he is getting with the resonant elevated radials.
Hope this helps. Although it is pretty abbreviated it was all I could manage
this weekend.
>From WM2C
The new Low Band DXing book has a lot of new stuff, and is well worth upgrading
to. I've always gone with insulated wire, for I usually can pick it up cheap
at the flea markets (in 500-10,000 foot rolls, and never pay more than $15 per
roll, regardless of size). I often combine multiple gauges too. How many?
the more the merrier, but once had a 160m 80' inverted-L with 2 radials on a
typical suburban lot in New York. Worked over 70 countries in 2 months in the
mid 80's. No scientific work to support my practices, I just use what I have.
>From WA3NNA
->I'm gonna shunt feed my largest tower for use on 160M. I had considered
->using an elevated system of radials, but thought wires running all over the
->place 10 feet above the ground didn't sit too well with me or the XYL.
->
->So... I need some opinions on a few things...
->
->1. How many radials & how long?
As many as possible. As long as possible. But really, a realistic minimum
for half decent performance is about 16, 32 is better. Once you start to get
near 100 you can stop. My 40 meter phased verticals had 100 1/4 wave radials
under each vertical. It worked very nice.
I have read a lot that if you can't put down a lot of radials then you
are better off with a lot of short ones than only a few long ones. This
has to do with higher current flow near the base of the antenna so the
losses there are greater. 100 10 foot radials might do better than 10
100 foot radials. As they say, your mileage may vary.
If you really want your vertical to "play" well, I would suggest a minimum
of about 50 1/4 wave radials. If you can get some longer then go for it.
->2. Type of wire? Insulated? Copper? Electric fence wire?
Whatever you can get the most of the cheapest. I wouldn't go any smaller
than 22 ga. 18-20 ga is fine. I think anything larger than about 16
or 14 ga is a waste of money unless you happen to already have lots of
it around. I would prefer to stick with copper but I suppose steel would
probably work OK. When I put up my 40 meter verticals, I ran into a place
selling 2500 ft spools of #20 insulated hookup type copper wire for
$10.00/spool! Needless to say, I bought all that they had.. My parents
backyard still has well over a mile of this stuff under the grass.
->3. How do you bury these things without wearing yourself out in the
->process? My tower is in the woods and won't have grass to hide the radials.
->Just alot of covered ground.
I did not "bury" mine. It was in a grass area. I just cut the grass real
short and spread out the wires and pushed the ends down into the ground to
hold them. The grass grew up around the wires and eventually they sort of
bury themselves. In no time I was able to cut the grass without bothering
the wires. I don't now about a wooded area but most likely anything left
on the ground will eventually get covered up. They only need to be just
below the surface so they stay put. No need to go any deeper.
>From KC8MK
You need to remember a few things:
1) 80% of the energy is within 50 feet of the tower.
2) Therefore, lots of short radials are better than a few long ones.
3) Ground rods buy you very little.
4) You need a really good buss to tie your radials to. I have some 2"
wide copper strap I can send you to make the buss out of.
Resonant antennas are better than non resonant ones. At WR8C/KC8MK, we
only have a 60' tower to play with. We built a 160 vertical by linear-
loading a piece of 14 guage wire held away from the side of the tower
by treated 2x4's. 35' up and 35' down, and 60' up again makes 130'.
It was good enough for us to finish 4th in ARRL 160, and we started 2
hours late.
Buy both of ON4UN's books. They are worth every penny and more.
For listening, read W1WCR's Beverage Antenna Handbook. These fellows
have it right, and really know what they are talking about.
>From N0BIW
Bill before I would put out radials I would check the latest issue of "the Low
Band Monitor" from Lance Johnson engineering. K0cs has a very informative
article about elevated radials and runs some comparison tests that are very
interesting too. It has made a few of us here in Kansas City think twice about
the present systems. Good Luck and gud dx
>From K1GW
Four or five years ago I loaded my 70 foot tower. It is topped with an
40-2CD and an A4. The matching rod is 1 inch diameter aluminum tube. The
matching network is similar to the Low band DXing design (As close as the
Dayton flea market would allow). By the way the length of the matching rod
is a lot less than the calculated length. W1PH, Kurt, installed it for me
and we had to eliminate several sections. My ground was suggested by NX1G,
Craig Clark. It consists of "chicken wire" from a local farm supply. The
first year I put out 150 feet by 4 foot length. The next year I added
another 50 foot length. Since the second length did not seem to make much
difference I have not added any more. The installation is in the woods.
Over the year pine needles have covered the chicken wire and walking on it
is a simple matter. The bandwidth (VSWR) is quite wide. I have no problem
using it over the active part of 160 without adjusting the matching device.
>From VE3CDX
>1. How many radials & how long?
120 radials at 200ft each (approx 3/8 wavelength) plus another 60 at 66ft each
( approx 1/8 wavelength)
>2. Type of wire? Insulated? Copper? Electric fence wire?
I've used just about anything as long as its copper. Old pieces of coax
make great radials. Most of mine are insulated and layed right on the
ground.
>3. How do you bury these things without wearing yourself out in the
>process? My tower is in the woods and won't have grass to hide the radials.
Can't help on this one as mine are all grass covered.
I feed my 40 meter tower (140ft with 3el full size 56ft boom) by running the
feed wire (spaced 4ft from the tower) right to the top then shorting it to the
tower. This makes the tower into a folded monopole on 160. The 40 meter yagi on
top looks like a top hat and effectively lengthens the antenna so it appears to
be very close to a 3/8 wavelength vertical. I use a piece of rg-213 as the feed
wire hung from an arm mounted at the top of the tower. A turnbuckle at the
ground end keeps tension on the wire.
>From WX0B
I loaded the 160 ft tower with lots of beams with a raised radial
system and gamma wire. Its a winner with only 4 135 ft wires.
Tune the wires like a dipole two at a time for 1830 or whatever
and use BIG caps for the omega feed. I use a large air cap 10kv or more
spacing and a big Vac Cap which i can tune thru an insultated shaft comming
out of the plasitic gargabe can waterproof (HI) box at 25 feet. Keep the
caps seperated with insulators from the tower since they get very hot. and
use insulators on the gamma wire to keep it from burning acrcing at the feed
point. I burnt the original rubber straps in two the first attempt.
It seems to work very well. and 4 radials are ok for cosmetics.
If I had 8 it would be unsightly. My feed is at 25 feet and radials slope
down to abt 10 feet at ends.
Gamma wire is abt 60 feet long and 8 inches off leg of tower.
I used one wire for gamma but will try to make it with 3 or 4 wires this
season to cut any loss there. It hears OK but Beverages are much much better
as to be expected.
73 Jay
>From N6TR
Well, I have never loaded a tower that high on 160 , but people have and
they seem to work okay.... however, my personal experience with even my
modest 95 foot tower versus the magic 65 foot height (and again confirmed
on 80 meters with 65 versus 45) is that the ones closer to quarter wavelength
in electrical length work really well.
Back in 1986 I had the loudest signal on 160 from Oregon. There were people
on hill tops with loaded 160 foot towers who I would beat out EVERY time.
W2GD has had similar results with a similar antenna (65 foot tower with 8 foot
mast, 5 ele 20 at 73 feet, 3 element 40 at 65 feet and side mounted
six element tribander half way up, 15 radials).
You might think about the idea N4KG had in a recent QST. Your elevated
radials would likely be so far off the ground, nobody would notice them.
Good ruck...
>From WN4KKN/VK1
Elevate them, don't bury them. Run them overhead if you must to keep them
out of the way. If you elevate them, you will only need three or four.
>From K4IQJ
Bill: I have a 60' aluminum tower with a CL-33 WARC on top. Directly above
this is a HF-2V set up as a 40M/30M ground plane with four 40M radials
fanning
out just below the beam. The total height is about 95 feet. The whole
thing is shunt fed on 80/160 with a single 40' gamma arm made of copper
tubing. It is matched with a single motor driven series capacitor (Heath
kit - not made anymore) and achieves less than 1.5 to one SWR anywhere on
80/75 M and less than 2/1 anywhere on 160M. The antenna is approximately
3/8 wavelength on 80M and is a very competitive antenna on that band. It
is about 3/16 wavelength on 160 and works very well there also (80
countries with 100W).
The original set up had 8 full length radials (.25 wavelenth on 160)
made out of some old aluminum fence wire (#14) that I had laying around +
about 6 random lenth wires - all buried just below the surface. It worked
well on 160M for 1-2 years but then performance seem to deteriorate on
160M. I discovered that the aluminum wire had become very brittle and most
of the radials were broken.
DON'T USE ALUMINUM WIRE!
I have been replacing the radials with #12 copper flexiweave a few at a
time. After reading in the handbook, I have decided to go with a larger
number of
shorter radials. Have about 8 60' radials down now. Will add three or
four more shortly. Not enough activity recently and conditions are worse
than several years
ago, so it is hard to compare performance. (I didn't have much trouble working
mults on 160 during the NAQP.)
On one support I have all bands 160-10M. It works well. I recommend the
shunt feed.
>From K9MA
One well-known principle is that, if you can only put in short radials, it
doesn't pay to put in many of them. If you can't make the radials more than
about 0.1 wavelength, a dozen of them get's you within a fraction of a
dB of a thousand radials. On the other hand, if you can make them all
0.4 wavelengths long, several hundred radials are worthwhile. Note, however,
that the loss with short radials is still higher than with a large number
of long ones. There's a table in the ARRL antenna book
---
Bill Fisher, KM9P
Concentric Systems, Inc. (CSI)
404-442-5821 Fax 404-667-1975
>From George Cutsogeorge <0006354141 at mcimail.com> Tue Aug 23 15:34:00 1994
From: George Cutsogeorge <0006354141 at mcimail.com> (George Cutsogeorge)
Date: Tue, 23 Aug 94 09:34 EST
Subject: Open Wire
Message-ID: <30940823143403/0006354141PK3EM at mcimail.com>
In the early 60s I put up a vee beam which was fed with KW 300 ohm
line and tuned for 80, 40 and 20. Every time it rained the loading
on my PL-172 amp would change enough to kick out the screen overload
relay and the presets for band changing were useless. Even after
waxing the line and twisting it the same would happen.
So I made up some open wire using #14 and plastic Polaroid film
spreaders left over from the Space Race. We were forever documenting
circuit operation with pictures of scope traces to bring to the
endless NASA design reviews so I had lots of spacers. The spacing
was about 3.5 inches I think. Anyway, this completely cured the
problem and there was no change in loading with rain or snow.
Fair Radio has some excellant spacers for open wire that are ceramic
and 2.5 x 0.5 inches. They would make a light weight line that
would be very low loss.
A few years ago I visited W1EVT, now KF1Z in the Boston area and
Clem had 12 towers on a hill top with driven wire arrays for all
bands and all directions. They were all fed with long runs of
open wire. Anyone who has ever been in pileups with Clem knows
how effective his arrays were.
George, W2VJN.
>From Jay Kesterson K0GU x6826 <jayk at bits.fc.hp.com> Tue Aug 23 15:49:34 1994
From: Jay Kesterson K0GU x6826 <jayk at bits.fc.hp.com> (Jay Kesterson K0GU x6826)
Date: Tue, 23 Aug 94 8:49:34 MDT
Subject: NAQP Power Levels (Changed)
Message-ID: <9408231449.AA23519 at bits.fc.hp.com>
> Well, I wonder how many people broke the rules this year?
> Good thing I read the 1994 NAQP rules in NCJ before the start of the contest.
> The power level now reads: 100 WATTS!! (No longer 150)
> Ok, fess up....who used 150 (or more) ?
> Later, Chad WE9V Kurszewski_Chad at macmail1.csg.mot.com
I did, I did (use 150 that is). The rules in the July QST say 150w.
I dug this note out of the CQ-CONTEST archive.
>From jholly at hposl42.cup.hp.com (Jim Hollenback) Tue Aug 23 17:44:24 1994
From: jholly at hposl42.cup.hp.com (Jim Hollenback) (Jim Hollenback)
Date: Tue, 23 Aug 1994 09:44:24 -0700
Subject: score
Message-ID: <9408230944.ZM1172 at hpwsmjh.cup.hp.com>
Results from WA6SDM
Band Q's mults
80 12 5 antenna still doesn't work
40 79 25
20 103 33
15 1 1
10 0 0
--- ---
195 64 = 12,480
10 and 15 were useful as a dummy load. The single 15m contact was in CA. yuk.
20 was okay, but I could never get any runs going. Maybe two at a time
would show up and then a big dry spell. Just ended up s&p'ing. 40 was okay,
actually had few mini runs. Guess I missed the move to 80. Hope the next
one is better.
Jim, WA6SDM
>From Mark Curran <curran at corona.med.utah.edu> Tue Aug 23 18:21:48 1994
From: Mark Curran <curran at corona.med.utah.edu> (Mark Curran)
Date: Tue, 23 Aug 1994 11:21:48 -0600 (MDT)
Subject: NAQP Score
Message-ID: <Pine.3.89.9408231158.A3939-0100000 at corona>
Call: KI7WX
Sec: UT
Name: Mark
Equipment: 930s, all band 88' dipole at 25 feet
B Q M
10 1 1
15 1 1
20 21 8
40 24 10
80 3 3
160 1 1
Time on: Sporadic 3 hours
51 x 24 = 1,224 pts (Please contain all laughter to one or two
short bursts)
Plans to go to super-station K6XO were dashed by wife's birthday.
I can't believe she had the audacity to be born on a contest weekend.
One very low wire antenna with 4000' of negative horizon to the east
does not make for a very good time. To compound matters 80 and 160
were +30db of QRN. Fun to work a few reflector regulars in this one,
and see you all in the Sprints.
Mark E. Curran KI7WX
Curran at Corona.Med.Utah.Edu
>From tree at cmicro.com (Larry Tyree) Tue Aug 23 20:25:56 1994
From: tree at cmicro.com (Larry Tyree) (Larry Tyree)
Date: Tue, 23 Aug 94 12:25:56 PDT
Subject: TR Logging Program version 5.0
Message-ID: <9408231925.AA10604 at cmicro.com>
There have been many additions to the N6TR Logging Program, and it has a
new name now. Please help spread the word as we keep our advertising
to a minimum.
TR LOGGING SOFTWARE Version 5.0
The TR Logging Software is a high performance logging system intended
to be used for most any contest or for normal QSOs outside of a contest.
It has been designed for the contest operator who is looking to use the
most efficient operating and logging techniques. The contest supported
by the program include: ARRL DX, ARRL 160, ARRL 10, Sweepstakes, CQ WW,
CQ 160, CQ WPX, NA Sprints, NA QSO Party, IARU Radiosport, South
American WW, Field Day (both US and European), WAE (both in or out of
Europe including QTCs), CQ M, All Asian, KCJ, JA International DX,
VK/ZL and most of the European contests.
The program includes the following features:
- NEW!! Color coded band map is fantastic!! You've got to see it.
Entries change color as they age. If you tune to a frequency on the
band map, the callsign of the station appears in the call window and
their exchange information in the exchange window. You can tell quickly
if this is the same station even if they aren't sending their call.
A simple press of the space bar will update the time. CQs and packet
spots also show up on the map and you can select any entry for an
instant QSY. An asterisk next to the call indicates a dupe.
- NEW!! Summary sheets for all supported contests.
- NEW!! DVP and DVK support. Backcopy support for DVP.
- NEW!! Band information on parallel port for Top Ten Devices decoder.
- NEW!! Interfaces to Kenwood/Yaesu/Icom/Ten-Tec radios.
- NEW!! Two radio CQ mode allows you to transmit 100 percent of the time!
- Multi-Multi support using single port interface.
- Industry leader in two radio CW support. Two radio operation becomes
effortless.
- 50K QSOs can be logged with only 640K
- Efficient operator interface allows you to increase your rate.
- CW run QSOs can be worked with 5 keystrokes (for a 4 letter call).
- Unique name database feature.
- Great CQP support. AI6V in NV is Nevada county, KI3V in NV is Nevada.
- Unique plus one calls from name database plus partial calls.
- Contest simulator.
- Configuration file gives you the flexibility to customize the program.
- Single paddle input supports two radios.
- Packet interface.
- Beam heading file.
- Use standard CT .CTY files for country updates.
- POST contest program does reports, mult checks, QSL labels, etc.
- CW weight control, 1-99 WPM, Curtis A or B keying, PTT control,
dynamic speed changes during message all add up to great sounding CW.
The program continues to grow and new features are always being added.
You can receive new updates via the 24 hour BBS service or over the
internet. Your purchase gives you 1 year of updates. You will not have
to pay a large sum to get the next major version as with some programs.
Current subscription rate for additional years is $15.
To order, send $50 to Larry Tyree N6TR, 15125 SE Bartell Road, Boring, OR 97009
In Europe contact SM3OJR (L.J.Silvergran at telub.se) or in Japan
contact JE1CKA (je1cka at nal.go.jp) for availability in those areas.
Note: The Icom/Ten-Tec interface is currently in beta-test mode. It is expected
to be finalized in the next month.
>From jholly at hposl42.cup.hp.com (Jim Hollenback) Tue Aug 23 21:22:41 1994
From: jholly at hposl42.cup.hp.com (Jim Hollenback) (Jim Hollenback)
Date: Tue, 23 Aug 1994 13:22:41 -0700
Subject: elevated radials
Message-ID: <9408231322.ZM1180 at hpwsmjh.cup.hp.com>
So with elevated radials up 8 to 10 feet, is the antenna also raised this
amount? Or do the radials slope down to a ground mounted antenna?
Jim, WA6SDM
jholly at cup.hp.com
>From ken.silverman at atlas.ccmail.AirTouch.COM (ken silverman) Wed Aug 24 01:45:52 1994
From: ken.silverman at atlas.ccmail.AirTouch.COM (ken silverman) (ken silverman)
Date: Tue, 23 Aug 94 16:45:52 PST
Subject: NA Contest Software
Message-ID: <9407237776.AA777685552 at atlas.ccmail.airtouch.com>
Has anyone used K8CC's NA Contest software recently? How stable is their
version 9? Any experience with the 1 COM port networking?
We're still looking for a way to network 1 COM port laptops... both NA and TR
now have operational 1 COM port networking. Using NA would be much less of a
learning curve for all if we need to switch from CT.
Please post your replies to me. I'll post a summary in a few days.
Many thanks,
Ken WM2C
ken.silverman at atlas.ccmail.airtouch.com
>From Richard Hallman <0006135537 at mcimail.com> Tue Aug 23 23:11:00 1994
From: Richard Hallman <0006135537 at mcimail.com> (Richard Hallman)
Date: Tue, 23 Aug 94 17:11 EST
Subject: Elevated Radials..
Message-ID: <81940823221118/0006135537NA2EM at mcimail.com>
I have a Tower that is 102 ft tall. 40-2CD at 112, TH7 at 102 and
a new Bottom TH7 at 55ft. Both TH7's are fed together with a homebrew
2:1 match box for upper,lower and both selection. ALL feedlines come
off the tower at 7 feet.
The Question??? Can I shunt feed the tower at the 7 ft mark and
run the radials from that 7 ft high mark where the feedlines come off??
Was told some time ago that having feedlines exit the tower, other than
at ground level, would not work.
Thanks for the help and KM9P for forwarding all his replies
to the Reflector......Very interesting.
Rich KI3V KI3V at mcimail.com
>From John W. Brosnahan" <broz at csn.org Wed Aug 24 02:37:00 1994
From: John W. Brosnahan" <broz at csn.org (John W. Brosnahan)
Date: Tue, 23 Aug 1994 19:37:00 -0600
Subject: ADDENDUM to my input to KM9P's posting on elevated radials
Message-ID: <199408240137.AA04785 at teal.csn.org>
Just wanted to clarify one point about radials now that my piece was
published on the net by KM9P as part of his summary of replies on radials.
My answer was a "quickie" and I decided that a little bit of clarification
is appropriate.
I mentioned that radials on the ground are not resonant so there is no
magic length. Actually this is an oversimplification. Ground mounted
radials are not usually used as resonant radials, they are just cut some
arbitrary length (typically 1/4 wave) and placed on or in the ground.
Tests indicate that extending them out further improves their performance
until some point of diminishing returns is reached in the neighborhood
of 3/8 to 1/2 wavelength, assuming enough are used (ie 60 or more).
Actually the ground loads the radials and they can be resonant, it is just
that at resonance they are only about 1/8 wavelength long which is too
short for really efficient operation. This has been verified on NEC by
By Dr. Richard Adler (K3CXZ, I believe), and in actual measurements on
the ground surface by Dr. Steven Franke (WB9IIQ). Raising them just a few
inches from the ground greatly reduces the detuning effect of the ground,
but they need to be significantly (5-10 ft on 80 and 10-20 ft on 160)
off the ground to become efficient elevated radials.
Hope this is a tidbit of useful information to be added to my comments.
73 John W0UN broz at csn.org
>From KG6AR at ix.netcom.com (CHRIS WILLIAMS) Wed Aug 24 04:58:21 1994
From: KG6AR at ix.netcom.com (CHRIS WILLIAMS) (CHRIS WILLIAMS)
Date: Tue, 23 Aug 1994 20:58:21 -0700
Subject: No subject
Message-ID: <199408240358.UAA29237 at ix.ix.netcom.com>
Does anyone know if Lance Johnson Engineering is still in business?
I would appreciate an address.
73 Chris KG6AR
>From K2ZJ <JVCARIOTI at c5vr.syr.ge.com> Wed Aug 24 12:05:27 1994
From: K2ZJ <JVCARIOTI at c5vr.syr.ge.com> (K2ZJ)
Date: Wed, 24 Aug 1994 7:05:27 -0400 (EDT)
Subject: Daiwa Rotors
Message-ID: <940824070527.25e04a3e at c5vr.syr.ge.com>
Great discussion going about the elevated radials. Very interesting!!
I want to know if anybody has information about parts for the old Daiwa rotors.
I have 3 of them and the indicator pots are becoming erratic.
I still see Daiwa products advertised, but I suspect that the rotors are no
longer made, even in JA land.
Any help with these rotors would be greatly appreciated.
73, John K2ZJ JVCARIOTI at C5VR.SYR.GE.COM
>From Peter G. Smith" <n4zr at netcom.com Wed Aug 24 13:55:40 1994
From: Peter G. Smith" <n4zr at netcom.com (Peter G. Smith)
Date: Wed, 24 Aug 1994 05:55:40 -0700 (PDT)
Subject: Lightning
Message-ID: <Pine.3.89.9408240554.A9795-0100000 at netcom>
I have ordered and read with great interest the informational package
that Polyphaser provides on their grounding and lightning protection
products. In reading it, though, I confess to a bit of skepticism about
the "mil-spec phenomenon," where the engineering is dandy but everything
is overdone by a factor of 5 or so. For example, their grounding plan
calls for MANY ground rods and radials at the tower base, a perimeter
ground around the entire building where the transmitter is located (with
many more ground rods), a low-impedance electrical interconnection between
the base of the tower ground and the house ground, a single-point ground
for the shack with protectors on each coax line, rotor cable(s), power
line and phone cables, and so on and so on. Sounds like I could easily
drop $4-500 just on lightning protection for my planned single-tower
station. On the other hand, I have heard some rather awesome stories
about the effects of a single hit, and the top of my antenna will be the
highest conductive structure for some miles in any direction, so ...
Questions for the multitude -
Do you use Polyphaser stuff? If so, how do you like it?
If not, why not? What do you use?
If you use the same basic approach, but scaled back, in what respects do
you feel it's OK to do so?
Has your installation taken a direct hit? Induced voltage hit? Effects?
I'll be glad to take responses by E-mail and then summarize for the
reflector if there is sufficient interest.
73, Pete
N4ZR at netcom.com
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