QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940330.txt

Internet Message Format | 1994-11-13 | 26KB

Date: Tue,  4 Oct 94 04:30:22 PDT
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
Errors-To: [e-mail]
Reply-To: [e-mail]
Precedence: List
Subject: Ham-Ant Digest V94 #330
To: Ham-Ant


Ham-Ant Digest              Tue,  4 Oct 94       Volume 94 : Issue  330

Today's Topics:
                             AEA Isoloop
                 Antennas are prohibited ...!!!!!!!!!
                     ARX-2B Transmitting problems
                    Best ant. for 2006? (discone?)
                   Best Antenna Modeling Software??
                    Double delat loop on VHF band
                       DX-88 Radials. How Long?
 FEEDLINE: Looking for mailorder cable places. Any recommendations??
           HF antenna questions from newbie ham (semi-long)
         Interference from computer causing receive problems
              NA4G's "National Electrical Code for Hams"
                           Parabola network
                     Scantenna vs. D-130J discone
                    using twin coax vs ladder line
                        What kind of antenna ?

Send Replies or notes for publication to: <[e-mail]>
Send subscription requests to: <[e-mail]>
Problems you can't solve otherwise to [e-mail].

Archives of past issues of the Ham-Ant Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives/ham-ant".

We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party.  Your mileage may vary.  So there.
----------------------------------------------------------------------

Date: 4 Oct 94 01:07:41 GMT
From: [e-mail] (Dave van De Kerk)
Subject: AEA Isoloop

Hello,
    I will shortly be moving into an apartment building which
is somewhat antenna friendly.  I could put an AEA Isoloop at about 20
feet off the ground (roofline) or I can string another long wire.

    I am asking all antenna wizards for their predictions.  Personal
experiences with long wires and loop antennas like the Isoloop or the
MFJ version most appreciated.  Owner testimonials appreciated.  Vender
info appreciated.  Horror stories appreciated.

    Issues I am interested in are TVI, RFI, RF safety and "getting
out."

    The Isoloop could be horizontal or vertical.

    The building is a four unit conventional stucco building with
plaster and (probably) chicken wire in the walls.  The whole building
is about 100 feet by 25 feet.  The roof is wood and has a very low peak,
maybe 2 feet above the lowest point.

    There are other "buildings" about the same size in the complex,
about 30 feet from our future unit.

    There are trees in the complex, and I could probably get a long
wire about 70 to 100 feet long, probably peaking about 25 to 35 feet
off the ground.

    Goals are reliable, hassle free S7 20 meter ssb operation out
to about 600 miles and 30 meter CW DX.  Intended power is 50 watts out
of an Icom 720 A.

    Grounding for a long wire worries me.  I'd be 20 feet from an
Earth ground, and this is dry California soil.  I would also string
counterpoise wires around the shack ... but ...

    Question: has anybody used the MFJ loop antenna?  Does it
compare to the AEA antenna?

    Please e-mail me as [e-mail] or [e-mail].
 ===============================================
 This message does not constitute any official or unofficial statement or
 policy of American Turnkey or any other organization, corporation or
 institution.
 -----------------
 David P. van De Kerk             Manager, Systems Integration
 American Turnkey                 Santa Ana, CA USA
 714-557-9050 x-168 voice         714-557-9056 FAX   [e-mail]
 KE6GXD

------------------------------

Date: 3 Oct 1994 09:52:01 -0400
From: [e-mail] (JimKD0AV)
Subject: Antennas are prohibited ...!!!!!!!!!

I use a Ventenna that was advertized in QST about a year ago or so.  Fit
right over the vent pipe and gets me into a dx packet cluster abt 25 miles
away.  For HF I run a center fed zepp through the trees on my property--
without the trees I suppose I would need a pop-up vertical.  73 and GL,
Jim KD0AV

------------------------------

Date: 3 Oct 1994 19:47:49 GMT
From: [e-mail] (Mike Bunney)
Subject: ARX-2B Transmitting problems

    I am having problems tuning my Ringa Ranger II.  I have adjusted
the bottom slide section to lengthen the distance, but I still only can
achieve no better than a -5 on my SWR meter.  The antenna sits on 2
sections of OD masting on top of my roof.  I have grounded the masting
and used a 50 ohm coax with 2 PL-259 connectors.  The connections seem
fine and all are tight.
    My reception is great, I only wish that my transmission was as good.


Any help or suggestions would be greatly appreciated.....


Mike Bunney
KC7BNQ

------------------------------------------------------------------------
Mike Bunney                Mail Stop:    JE-41
FMS Manager                Phone:        [phone]
Physical Plant Dept.            Fax:        [phone]
University of Washington        E-Mail:    [e-mail]

------------------------------

Date: 3 Oct 1994 22:10:05 -0400
From: [e-mail] (N2dvq)
Subject: Best ant. for 2006? (discone?)

In article <36pu0q$[e-mail]>, [e-mail] (
) writes:

>
>
>
Create systems has a very nice Log Periodic Antenna that will cover from
100-1000 well. It requires a rotor, but has much gain over a discone. This
ant will out perform the discone at UHF freq's by a ton. Mine has been up
for 6 years and looks and performs like its brand new.

There is a low freq version but it is big and costly for 50 MHz and up.
Try Texas towers or other ham dist. They all know of it and some have it
in stock.

good luck

------------------------------

Date: Mon, 3 Oct 94 10:41:20 MST
From: "William P. Osborne" <[e-mail]>
Subject: Best Antenna Modeling Software??

On 3 Oct 1994 04:50:06 GMT,
Gary T. Schwartz  <[e-mail]> wrote:

>
>I am interested in getting some feedback from users of popular antenna
>modeling software.  I am interested in modeling wire antennas and phased
>arrays on the HF bands.  I am NOT interested in modeling Yagis.  What are
>the differences between popular software such as ELNEC and Antenna
>Optimizer (AO)??  Do both of these packages accurately model antennas over
>"real ground" as well as free space??
>
>Do both packages accurately model things like elevated radial systems a
>few feet above ground??  Or how about low horizontal antennas such as a 40
>or 80M "cloudwarmer"?
>
>How do these two packages differ regarding their ease of use??
>
>What type of modeling software are you using out there??
>
>Are there any others worth looking at??
>
>Finally, does anyone know of any mail-reflectors or Usenet forums that
>discuss these topics??
>
>Thanks for your help.....73 Gary K9GS
>

Gary,  I have Elnec, AO, NEC/Wires and YO as well as a version of NEC from
the Oak FTP site.  Elnec is the easiest to use of any of them.  It is a
Mininec program and has the weaknesses of that approach, i.e., horzonial
wires below .25 lamba and wires close together (transmission
lines) are a problem.  This means that LPA and some 160/80 meter antennas
with low wires like delta loops will be a problem.  Roy, the fellow who
wrote Elnec wrote a good article in QST a while back on these issues and I
think it is in the new handbook also but I'm not sure.

NEC has a much better ground modelling capablity but is very much harder to
use as it is basically a batch program that you define an input antenna for
using a text editor one wire at time.  However,  NEC/Wires is a pretty good
implimentation of a front-end for NEC giving you some good graphics for
output.  When you combine it with AO you get a Mininec based AO with which
you can use to test the input file before you go to the trouble of running
NEC.  AO is competitive with Elnec in terms of algorithms but Elnec's
interface is better and easier to use IMHO.  AO will allow you to optimize
various parameters of any antenna but it maybe slow and/or inaccurate in
doing this because optimization is very cpu intensitive and it is a
mininec algorithm.
Hope this is somewhat of a help.  CUL

William Osborne, AA5ZQ        505-646-3919
Professor ECE Dept.           PO BOX 30001, Dept. 3-O
New Mexico State University   Las Cruces, NM 88003-0001

------------------------------

Date: 3 Oct 1994 19:39:14 GMT
From: [e-mail] (Fredric Tronel)
Subject: Double delat loop on VHF band

I've built a double delta loop antenna ,after I've read an article on a french review.
The original text has been written by G4ZU Dick.
Here's a description of the antenna :

   (one element)                   ________
                                   \      /
                                    \    /
                                     \  /
                                      \/
                                      []    <---- boom
                                      /\
                                     /  \
                                    /    \
                                   /______\

According the author :
     .On the 10 meters band with 2*2 elements :
           (Computered) Gain : 10 Db(d)
                        Widthband : 1 Mhz
My own experience :
      .On the the 2 meters band with 2*6 elements :
                    Widthband : 3~4 Mhz (TOS < 1.5)
                    Tos center of the band : 1~1.1
                    Important gain
                    Fed by two gamma match with 2 capacitors.

So if you have informations about such antenna ,or if you want further info ,my mail:

    [e-mail]

 73's from F1SDZ (Fred)




------------------------------

Date: 3 Oct 1994 08:01:13 -0500
From: [e-mail] (Kris I. Mraz)
Subject: DX-88 Radials. How Long?

I have a Hy-gain DX-88 vertical antenna but no manual. I am mounting it
as a temporary antenna elevated about 10 ft off the ground. Can anyone
tell me the length of the radials recommended by Hy-gain?

73
Kris AA5UO
[e-mail]

------------------------------

Date: Mon, 3 Oct 1994 12:30:09 GMT
From: [e-mail] (andrew peter.cropley)
Subject: FEEDLINE: Looking for mailorder cable places. Any recommendations??

  Looking to get myself some cable. I will be operating on VHF and UHF
so I want to get some real high quality line. I don't think I can afford
Hardline (connector prices are incredible!). I heard that RG214 is pretty
good stuff (better than 9913). I think this runs around 1.50 / foot.
Does any one have the specs for RG214??
Are there any other "high-grade" cables out there in this price range??
I was considering a polytetrafloroethyalene dialectric (teflon) since it
has high heat ratings (up to 250 degress Celsius). comments?

Last Q, any recommended mail order dealers. I see adds for the cable X-perts
in QST, but I don't see to many others. I do want to make sure I'm getting
my best price.

   Thanks in advance

     Andy C


     N2ZAM

------------------------------

Date: 3 Oct 1994 15:28:50 GMT
From: [e-mail]
Subject: HF antenna questions from newbie ham (semi-long)

In article <[e-mail]>,
Robert Adams <[e-mail]> wrote:
>
>A tuner induces a loss. An unnecessary tuner induces and unnecessary loss.
>I don't even own a tuner... and wouldn't waste my money buying one.

Hi Robert, it just depends on what you want your antenna to do.
The antenna tuner induces less than 0.5db loss according to the Antenna
Handbook, neglible on an 'S' meter. My 88 ft CF dipole works all the way
from 80m to 10m with impedances that vary from low to 3000 +/- j3000,
impossible to match to a solid state rig without a tuner of some sort.
It has a two-lobe 9dbi gain on 20m and a four-lobe 8 dbi gain on 17m over
real ground. It has more gain and a lower angle of radiation on 20m than a
20m resonant dipole. I feed it with 450 ohm ladder-line from a 4:1 balun.

There are a lot of advantages to all-band non-resonant dipoles.
--
73, Cecil, KG7BK, OOTC           Most of the doors in amateur radio can
(Not speaking for Intel)         not be opened by a  -.-.  .--  key.

------------------------------

Date: Mon, 3 Oct 1994 17:55:44 GMT
From: [e-mail] (David Tiller)
Subject: Interference from computer causing receive problems

Russ Blaine ([e-mail]) wrote:
: My friend has a CB radio that works fine - when his computer is off. When
: he turns the computer and monitor on, the static and hiss level on his
: radio go way up, making transmissions very hard to hear and some almost
: indiscernable.

: Questions:
: How can we get rid of this?
: 1) Would something like a lead box around the actual CB radio eliminate
: this?

Lead wouldn't be a good choice.  It might shield from Gamma rays, but as
a conductor it isn't all that great.  To prevent RF infiltration, you want
the best conductor you can get - usually copper- or silver-based paint or
braid to seal the enclosure.

: 2) Would a lead box around the computer eliminate this?

No.  You'd never be able to move it again, though.

: 3) Is it the antenna's fault (we're using a homemade 1/2 wave dipole
: mounted vertically)?

It's the antenna's fault (possibly) in that it's too close to the
computer.  If you've got the coax and space, move it outside and away
from your computer.  If you've got bad connections/open spots in the
coax, you're asking for trouble, too.  What kind of coax is he using?
Decent stuff, or Rat Shack RG-58?  The better the shielding on the coax,
the less signal infiltration you'll get.

: 4) Any suggestions as to where I can find sheets of lead (if that's the
: answer) and how to put it up?

Again, try to get some copper paint and braid to seal the cabinet.  Ask
around for suggestions - I don't know of any brand names.


: The interference is not coming specifically from the monitor or computer,
: but both.

Yes, that's correct.  Usually the worst radiators are cables connecting
pieces.  Try ferrite beads/donuts on them, sometimes that'll help.

: Is the interference (apparently caused by electro-magnetic fields from
: the monitor and computer, right?) getting picked up by the antenna, the
: radio itself, or both?

It could be both, depending on how well (or poorly) they're shielded.
Try connecting a PL-259 with a 47ohm resistor (or a good dummy load) across
the CB.  Listen and see if you've still got interference.  If so, the radio
itself is getting RF into it.  If not, it's either the coax or the antenna's
proximity to the computer.

--
David Tiller                | Network Administrator | Voice: [phone]   |
[e-mail] |  n2kau/4  | Randolph-Macon College| Fax:   [phone]   |
"Drunk, [Beowulf] slew no   | P.O. Box 5005         | ICBM:  37d 42' 43.75" N |
hearth companions."         | Ashland, Va 23005     |        77d 31' 32.19" W |

------------------------------

Date: 3 Oct 1994 16:19:44 GMT
From: [e-mail] (Stephen Modena)
Subject: NA4G's "National Electrical Code for Hams"

[ At the end this are instructions for retrieving the file via Internet.]

   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % Article by Robert D. Keys (NA4G) on the National Electrical Code as it %
   % may apply to amateur radio stations.  This is an interpretation based  %
   % upon the author's experiences, studies, and reading of the Code.       %
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % This article is copyright, 1994 by Robert D. Keys (NA4G).              %
   % All rights reserved, worldwide.                                        %
   % Public non-commercial distribution of this work is authorized.         %
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % This article is typeset using the LaTeX Technical Typesetter.          %
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   % REVISION OF 26 JAN, 1994                                               %
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


                                 ABSTRACT

        This work was presented as a talk to  the  Homebrew  Special
        Interest Group (HB-SIG) of the Raleigh Amateur Radio Society
        (RARS), on 15 January, 1991  and  was  revised  for  another
        presentation on 26 January, 1994.

        This  document  contains excerpts of the National Electrical
        Code (NFPA 70-1990) that, in the author's opinion, apply  to
        the   installation  of  amateur  radio  equipment  as  would
        commonly be found in most amateur  radio  stations.   Direct
        excerpts   from   the   Code   are  contained  within  inset
        quotations.   Paraphrased  excerpts  from   the   Code   are
        itemized.  The author's interpretation and discussion of the
        Code is set full-width.   The  author's  interpretation  and
        discussion  of  various sections of the Code is not meant to
        be all-encompassing, nor the official interpretation of  the
        National  Fire  Protection  Association,  nor of any offical
        governing body having legal authority of  jurisdiction  over
        electrical  installations,  but  is  meant  to  be used as a
        teaching tool for amateur radio operators.

        Robert D. Keys, NA4G
        Raleigh, NC,
        25 September, 1994.


Enjoy
73 DE NA4G
Boatanchor Bob

**************************************************************************
*  73 TU SU SK DE NA4G             ``Boat Anchor Bob'', an ol' CW fart.  *
**************************************************************************
*  Morse has been in the family for over 100 years.                      *
*  Morse radiotelegraphy (Spark/CW) has been in the family since 1914.   *
**************************************************************************
*  May you have fair winds and following seas on your watch at the key.  *
**************************************************************************

[ The files referred to in this 'readme' can be retrieved by
  anonymous ftp from two archive sites:

    SunSITE.unc.edu    (permanent)
    /pub/academic/agriculture/agronomy/ham/things-to-build/na4g

    ftp.Cybernetics.NET   (temporary)
    /pub/users/ab4el

  For ease, the group of files have been 'rolled into one'...

   nec-1994.tar.Z  861,677 bytes (for Unix jocks)
   nec-1994.zip       732,309 bytes (using PKZIP 2.04g for MS-DOS users)

  Download one or the other according to your computer/print facilitites.

  Don't forget to set 'binary' mode before 'get'...else they will
  come to you as trash.  :^)

  de AB4EL ]

---------------Cut Here------------------

------------------------------

Date: 3 Oct 1994 16:09:50 GMT
From: [e-mail] (Elendir)
Subject: Parabola network

 Hi again,
 first of all, thanks for all the replies regarding the omnidirectionnal SHF
antenna. That was for a repeater project.
 Now,...
 I am also interested in a 10 GHz EME project. That means a lot of gain. I've
thought about building a 3 meter dish, but this is rather large and at best
uneasy. Therefore, I wonder if it is possible to replace such a big antenna by
a network of small dishes.
 Of course, some problems remain : moon tracking, phasing of each dish.

 What do you think about that ?

 Thanks and 73s !

 Vincent

--
F1RCS - Worldwide Friendship through Amateur Radio
ENST, Ecole Nationale Superieure des Telecommunications, Paris

------------------------------

Date: 3 Oct 1994 19:51:55 GMT
From: [e-mail] (Ryan K. Brooks)
Subject: Scantenna vs. D-130J discone

I'm looking for a good reception antenna that can cover 6M, 2M, 70cm and
900MHz omnidirectionally.  It seems like both the Diamond 130J discone and
the AntennaCraft Scantenna would be suitable for this.  Anyone have
recommendations?  I'm sure many other people would be interested in this
also, since these two antennas seems to be fairly popular.

--
 ------------------------------------------------------------------
  Ryan K. Brooks                       [e-mail]
  "Is is and isn't isn't."

------------------------------

Date: 3 Oct 1994 19:10:57 GMT
From: [e-mail] (Tom WB7ASR)
Subject: using twin coax vs ladder line

Lou

At the bauln outside your house, I assume your tieing the center
conductor of each coax to the bauln's output terminals, however what do you do
with the sheilds, tie them together to ground or let them float? When you run
the two coax cables to the antenna, did you just tape them together? Is there
any critical spacing? At the feed point of the antenna, does the sheilds float?
Did you use 50 or 75 ohn coax, or doesn't it matter?

This idea sounds interesting, I have a ton of 50 ohm surplus coax and I might
give it a try.

Tom WB7ASR...

> I am using two coax lines as a feed for a full wave 80 meter loop.  It's
> known as shielded open wire and works great.  The antenna is fed through
> a tuner and a unbalanced to balanced bauln.  The output of the tuner is
> fed to a short length of RG8 that goes into the bauln, which is located
> just outside the shack.  The output of the bauln is balanced and feeds
> the two lengths of RG8 coax.
>
> There are some advantages to using this method over standard open wire -
> 1. -  You can route the coax much easier since it does not have to be
> spaced away from the tower, mine is taped to the tower itself.
>
> 2. - Noise pickup on the transmission is reduced.
>
> 3. - Feedline is very weather resistant, if you use good coax.
>
> One of the recent ham mags had a quickie writeup on it, if I find it
> again, I will pass the info along.
>
> The antenna has been used on 40 and 80 for a number of years with
> excellent results.
>
> Lou Nigro - KW7H
>
>

------------------------------

Date: 3 Oct 1994 15:14:51 GMT
From: [e-mail] ()
Subject: What kind of antenna ?

Udo,

I think the best antenna is the turnstile (Drehkreuz) antenna
made from two folded dipoles with proper combiner-phaser.
+ a cross dipole reflector.
The VHF communications have some times ago published a much
simpler design, but this requires determination the WSWR
of the individual dipoles before fully assembling.
I have posted this instead of answering directly, since I
am interested in alternative opinions. I know there is
a design looking like a pair of twisted frames.

73, Moritz Dl5UH

------------------------------

Date: Mon, 3 Oct 1994 17:56:46 GMT
From: [e-mail] (David Tiller)

References<[e-mail]> <[e-mail]>, <[e-mail]>
Subject: Re: 2 Meter SWR meter schematic????

andrew peter.cropley ([e-mail]) wrote:
: In article <[e-mail]> [e-mail] (Gary Coffman) writes:
: >In article <[e-mail]> Mike Lyon <[e-mail]> writes:
: >>
: >>does anyone out there by chance have a schematic for a swr meter for 2
: >>meters? or know of a place where i can get one?
: >
: >The RSGB VHF UHF Book has a project that makes one out of some standard
:      ^^^^
:       What's this stand for??

Radio Society of Great Britain.  They put out good books that are sold thru
the ARRL.
--
David Tiller                | Network Administrator | Voice: [phone]   |
[e-mail] |  n2kau/4  | Randolph-Macon College| Fax:   [phone]   |
"Drunk, [Beowulf] slew no   | P.O. Box 5005         | ICBM:  37d 42' 43.75" N |
hearth companions."         | Ashland, Va 23005     |        77d 31' 32.19" W |

------------------------------

Date: Mon, 3 Oct 1994 22:09:44 GMT
From: [e-mail] (Robert Adams)

References<36eo65$[e-mail]> <[e-mail]>, <36p7vi$[e-mail]>
Subject: Re: HF antenna questions from newbie ham (semi-long)

In article <36p7vi$[e-mail]>,
 <[e-mail]> wrote:
>In article <[e-mail]>,
>Robert Adams <[e-mail]> wrote:
>>
>>A tuner induces a loss. An unnecessary tuner induces and unnecessary loss.
>>I don't even own a tuner... and wouldn't waste my money buying one.
>
>Hi Robert, it just depends on what you want your antenna to do.

Not at all. The tuner deals with feedline impedance... not the antenna.

>The antenna tuner induces less than 0.5db loss according to the Antenna
>Handbook, neglible on an 'S' meter.

Don't take one of my classes! On second thought... you can't... I retired.
<grin>

>My 88 ft CF dipole works all the way

That's all well and good, Cecil. But, you're using a balanced feedline and
it was an _unbalanced_ feedline that was under discussion. Apples & oranges.

>It has a two-lobe 9dbi gain on 20m and a four-lobe 8 dbi gain on 17m over
>real ground. It has more gain and a lower angle of radiation on 20m than a
>20m resonant dipole.

Not meaning to sound flippant... but, just how did you arrive at those
figures? DBI? Sounds like modeling software... not real world data.

>I feed it with 450 ohm ladder-line from a 4:1 balun.

And, again, what has this to do with 50 ohm unbalanced lines?

>There are a lot of advantages to all-band non-resonant dipoles.

That's what people with all-band non-resonant dipoles invariably suggest.
;->

Robert Adams, PE
WA9ZMO
[e-mail]

 * "FREE (U.S. from) WILLY!" Vote Republican in November!

------------------------------

End of Ham-Ant Digest V94 #330
******************************