QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940343.txt

Internet Message Format | 1994-11-13 | 16KB

Date: Thu, 13 Oct 94 04:30:18 PDT
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #343
To: Ham-Ant


Ham-Ant Digest              Thu, 13 Oct 94       Volume 94 : Issue  343

Today's Topics:
                        2 Meter SWR meter sch
                      Antenna length question...
                 Anyone have plans for a 220 J-pole?
                          Dipole Not Working
           does anyone have the phone number for heathkit?
                     Enough already! I want 80m!
                Ice problems on Mountaintop microwave
                I need help with antenna calculations
                  need advice on sloper installation
                        Superior coaxial line?
                        SWL Antenna for Attic
                       Tiger Tail (HT antenna)
                    want to build cranck up tower

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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: Tue, 11 Oct 1994 20:50:44 GMT
From: [e-mail] (Jacques Choquette)
Subject: 2 Meter SWR meter sch

Neagative. I live in Canada and had purchased last year such an
excellent instrument. Problem is a friend started building antennas ans
wanted to purchase one. Went to several stores in Us and seems they are
no more on sale with no reason reason. Only reason we could figure out
was that it ti closely resembled another company's and thus might be on
patent infringing/copyright? Nowadays, who really knows!!

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

Date: Wed, 12 Oct 1994 20:01:17 GMT
From: [e-mail] (Phil Dennis)
Subject: Antenna length question...

I have a 2m 5/8 wave mag-mount antenna from Radio Shack that I am using
for my scanner.  As most of my scanning is just above the 2m band
(~160Mhz rail frequencies), I was wondering if trimming a couple of
inches off of the length would help reception.  From what I figure,
the 48" antenna is about a perfect match for 146 Mhz.  Would trimming
that down to about 44 inches (about 5/8 of a 160 Mhz wave) be the
correct thing to do, or should I take of more (or less) to take into
account the loading coil?

Any help would be appreciated.

*************************************************************
*Thanks to the Interstate Highway System, it is now possible*
*to travel across the country from coast to coast without   *
*seeing anything.       --Charles Kuralt                    *
*                                                           *
*ALL STANDARD DISCLAIMERS APPLY,           Next time,       *
*[e-mail] A.K.A. PHIL DENNIS   take the train!  *
*************************************************************

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

Date: 12 Oct 1994 08:30:00 -0700
From: [e-mail] (Jim Garver)
Subject: Anyone have plans for a 220 J-pole?

In article <37f14i$[e-mail]>,
Michael Malloy <[e-mail]> wrote:
>I just got a 220 HT and would like to build a twin lead or copper j-pole
>to get better coverage. Any help would be appreciated.

Yes, somewhere I have plans from a magazine on how to build a 220 (222?)
jpole out of twinlead, but you don't want to do it, I tell ya.
I built the thing, we tried it in various orientations, and it was
marginally better than a rubber duck.  I then bought an AEA hotrod 222 Mhz
antenna for $20 from HRO and it works outstanding.  This is an end-fed
half wave antenna like the jpole, but matched with a coil transformer
instead of the 1/4 wave matching section of the jpole.  So its shorter.
I did try to build my own hotrod antenna but it was mechanically unsound.
Not to say that the AEA hotrod is rugged or something, but mine was worse.



--
[e-mail]  WA7LDV    "Each day is like a crisp new dollar bill.
I speak only for myself.            How will you spend it?" - Barnaby Jones

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

Date: 12 Oct 1994 14:12:51 -0500
From: [e-mail] (James Meade)
Subject: Dipole Not Working

My folded dipole quit giving good reception into my Kenwood TS-440-S.
I have not transmitted on it.   When I pull the antenna out enough so
the outer ground does not touch, reception is fine.

The ground and hot leads show a dead short in the antenna (not lead
wire).  This antenna has a balun at the lead point, and another balun
or something opposite th e connection point on the other wire.

I think this is similar to an MFJ antenna.  It has been doing a good
job for me till now.  I think it is a 10-80m.


--

Jim - Farmer - Iowa City, IA,
[e-mail]

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

Date: Wed, 12 Oct 1994 16:13:12 +0000
From: [e-mail] ("Anthony R. Gold")
Subject: does anyone have the phone number for heathkit?

In article <[e-mail]>
           [e-mail] "Shel Darack" writes:

>
> About a year ago someone posted it as
>                 616 925 5899

My information is older. I spoke with someone at a store in 1992
on 616-925-4914.

Old numbers in my list are 800-253-0570 for orders, 800-444-3284 for
documents and 616-925-2190 as an additional store number.

I always thought their stuff was junk except for the SB-220, which was
a bit lightweight but had acceptable performace for me.

I was chasing them for HERO-1 robot stuff. Also crap quality, but
unfortunately the japanese firms never offered one.

I'd be pleased to contact any HERO-1 owners.

--
Tony, G3SKR and AA2PM

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

Date: Wed, 12 Oct 1994 13:43:57 GMT
From: [e-mail] (Zack Lau (KH6CP))
Subject: Enough already! I want 80m!

Sean E. Kutzko KF9PL ([e-mail]) wrote:

: Greetings, all...
: I have finally had enough of 20 and 40 meters, and am trying to come
: up with a reasonable 80 performer for 80m. I live in an urban setting
: with a small yard, and no practical access tothe front yard.  Vericals
: are out of the question...no room for supports or guys. Certainly no
: room for a dipole, nor do I have tall enough trees to get it a 1/4 wave
: up.

: Honestly, I want a DX performer for a SMALL city lot. Knowing that this
: is a HUGE order to ask for with the limited space I have, I got to thinking

How about operating from a portable location?  Not exactly the easiest
thing to do, but I know of at least one amateur who runs 160 meters
from his sport/utility vehicle.  He uses a half wave mostly vertical
antenna supported by one of those blimps you see at car dealerships.

--
Zack Lau  KH6CP/1           2 way QRP WAS
                           8 States on 10 GHz
Internet: [e-mail]   10 grids on 2304 MHz

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

Date: 12 Oct 1994 17:57:11 GMT
From: [e-mail] (Bayard Coolidge USG ZKO3-3/S20)
Subject: Ice problems on Mountaintop microwave

--
In:
Subject: Ice problems on Mountaintop microwave
Message-ID: <[e-mail]>
Summary: Anyone got experience with ice on Microwave antennas?

Richard Barnaby (AA1IB) Central Vermont Amateur Radio Club, Montpelier, VT
[e-mail] asks:

 Question: If the 5" horn ices up on the mouth, we will have zero
signal.  We expect significant ice on the peak.  Is there some
material we can enclose the horn in that will shed ice?  If we install
an ice dam over the horn, its possible that the ice will coat both
the dam and the horn.  Anyone got creative ideas?

Semi-whimsical answer from N1HO:

Would a large Tupperware (R)(TM)(C) container do the trick?
What are the overall dimensions of the antenna? Maybe a big salad bowl
(with a detachable lid) turned upside down might do the trick. But, I
guess you'd better get one rated for freezer use.
Unfortunately, I don't have any direct experience with this stuff, and
I don't know how much attenuation the plastic has in the microwave band,
but it would at least keep the snow and ice from blowing into it.

73 de n1ho (fn43ig)
-----------------------------------------------------------------------------
Bayard R. Coolidge    N1HO     DISCLAIMER: The opinions expressed are
Digital Equipment Corp.        solely those of the author, and not
Nashua, New Hampshire, USA    those of Digital Equipment Corporation
[e-mail]        nor any other entity.
    "Brake for Moose - It can save your life" - N.H. Fish & Game Dept.
-----------------------------------------------------------------------------

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

Date: 12 Oct 1994 17:54:28 GMT
From: [e-mail] (Gary Kabitzke)
Subject: I need help with antenna calculations

I want to be able to calculate the approximate impedance of a
telescoping antenna at different lengths and frequencies.

For instance, I know that at 320mhz a 1/4 antenna should be about 9.2".
But lets say I want to use a 3" or 4" or maybe a 30" antenna. I see
loading coils used to resonate CB antenna systems. Is there a general
calculation that can give me the impedance of an antenna(capacitive or inductive)
at a given length and frequency.

Thanks in advance for your help.

Gary

***********************************************************************
Sometimes I feel like I'm somewhere in between the end of the road and
the middle of nowhere.
***********************************************************************

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

Date: 12 Oct 1994 20:30:47 GMT
From: [e-mail] (Fred J Helmstetter)
Subject: need advice on sloper installation

Has anyone out there used the Alpha-Delta DX-B shortened sloper? I'm
thinking about installing one before the snow starts to fall and would
like to hear any comments you may have. Performance? Ruggedness?

A question about slopers in general: I realize the best set up is to run
the wire down off a tower with a beam on top using the tower as ground
return path. Has anyone had any luck using a non-metallic structure with a
wire run down the groud side ? How critical is the angle at which the ground
wire and/or transmission line come off the feedpoint?

Thanks for any info.

73,

Fred, WB2WDW/9

--
------------------------------------------------------------------------------
Fred J. Helmstetter                [e-mail]
University of Wisconsin-Milwaukee        [phone]
------------------------------------------------------------------------------

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

Date: Wed, 12 Oct 94 07:50:43 EDT
From: [e-mail] (Bob Hamilton)
Subject: Superior coaxial line?

In <37eknt$[e-mail]> Galen Watts writes:
>In article <[e-mail]> [e-mail] (Bill Splaine) writes:
>>: RS was .59/ft for RG-8,  and another company (local) was .60/ft
>>: Belden 9913 I'll have to call around for this one.
>>I haven't bought RS coax, but one of my friends works there and says that
>>their coax is not bad stuff but the prices are VERY HIGH compared to AES and
>>other suppliers.
>
>Cable Experts, 1-800-828-3340
>RG-8/U Foam, $0.32/ft, >100ft
>9913 Equiv   $0.47/ft, >100ft
>9913 Equiv flexi, $0.62/ft, >100ft
>
Cable Experts carries a full line of R/F cable and connectors as well as
accesories (coax seal, baluns, etc). Call them for a catalog. Their
service is great.

=========================================================================
Bob Hamilton                | Remember..The light that you see at the end
([e-mail])   |  of the tunnel just might be a train !
=========================================================================

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

Date: Wed, 12 Oct 1994 04:52:32 GMT
From: [e-mail] (Bill Turner)
Subject: SWL Antenna for Attic

In article <377ki0$ogs$[e-mail]>,
Rush Johnson  <[e-mail]> wrote:
>I would like to hear some suggestions on a good SWL antenna that
>I could build/buy to put in my attic.  The attic is about 30 by
>50 feet in dimensions.


For listening purposes, a simple dipole fed with RG58/U coax will work
fine.  If you have a favorite band you want it to work best on, use the
formula length(feet) = 468/f(MHz).  For instance if you want it for the
31 meter band, the length would be 468/9.6 = 52 feet overall.  Since
it's going in the attic, weather and wind will not be a problem, so
virtually any kind of wire will do.  If you don't have a favorite band,
just make it as long as will fit in the attic.  You no doubt see a lot
of posts on this newsgroup about fine-tuning antennas, but that's for
transmitting purposes.  For receiving with a fairly decent receiver made
in the last few years, it's nowhere near that critical.

If you really want to understand antenna theory, the ARRL publishes an
antenna handbook that is excellent for beginners and old timers alike.
Write them at:  225 Main St, Newington CT 06111.


73, W7LZP



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

Date: 12 Oct 1994 16:51:35 GMT
From: [e-mail] (Scott Turner)
Subject: Tiger Tail (HT antenna)

Bob Levine ([e-mail]) wrote:

: I discovered that in the plane of the HT (my FT530), the signal strength
: is greatly increased with the TT.(>2x) The signal strength directly
: above the HT goes way down.  The TT seeems to increase the lobes
: in the horizontal plane and reduce the amount of energy going
: vertical.  I did these tests the best I could with the HT in
: a plastic holder and keyed up from about 5 feet away with a
: speaker mic so I would interfere as little as possible.

Bob, I would respecfully submit that your test is a bit flawed.  For
normal usage, you *are* part of the antenna system on an HT.  Performing
the test with your body away from the antenna won't give you realistic
results.

Some time ago, a friend was playing around with a network analyzer and
decided to look at his 2 meter HT antenna.  He was somewhat surprised to
find that it appeared to be resonant outside the 2 meter band.  He then
moved his head next to the antenna and tried again.  You guessed it.
The antenna was now nicely resonant inside the band.

My guess is that your body's proximity to the antenna will have about as
much positive affect as the TT does.  In other words, I remain sceptical.


Scott Turner KG0MR  [e-mail]

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

Date: Thu, 13 Oct 1994 08:09:26 GMT
From: [e-mail] (Yoram Rotbach)
Subject: want to build cranck up tower

Hello and thank you for reading this
------------------------------------

I would like to build a cranck up tower (small one - about 6m). If you
know of a method of construction of such tower pse let me know.

73 de Yoram 4z9dea

[e-mail]
[e-mail]
[e-mail]

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

End of Ham-Ant Digest V94 #343
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