home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
QRZ! Ham Radio 4
/
QRZ Ham Radio Callsign Database - Volume 4.iso
/
digests
/
antenna
/
940245.txt
< prev
next >
Wrap
Internet Message Format
|
1994-11-13
|
22KB
Date: Tue, 2 Aug 94 04:30:22 PDT
From: Ham-Ant Mailing List and Newsgroup <ham-ant@ucsd.edu>
Errors-To: Ham-Ant-Errors@UCSD.Edu
Reply-To: Ham-Ant@UCSD.Edu
Precedence: Bulk
Subject: Ham-Ant Digest V94 #245
To: Ham-Ant
Ham-Ant Digest Tue, 2 Aug 94 Volume 94 : Issue 245
Today's Topics:
20m dipole problems HELP
2m antenna on VW Golf/GTi, where?
Best HF mobile antenna?? (3 msgs)
Comet CA-350DB
Hygain Hytower-2
JPole fundamentals
New
Q:SW car antenna?
Question: Powerlines surrounding Antenna
Trade hf 5 band verticle 4 yaesu ft11r
What coax feed to use for 2m antenna (2 msgs)
Send Replies or notes for publication to: <Ham-Ant@UCSD.Edu>
Send subscription requests to: <Ham-Ant-REQUEST@UCSD.Edu>
Problems you can't solve otherwise to brian@ucsd.edu.
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: Sun, 31 Jul 1994 08:33:50 GMT
From: lll-winken.llnl.gov!uwm.edu!news.alpha.net!mvb.saic.com!eskimo!levi@ames.arpa
Subject: 20m dipole problems HELP
To: ham-ant@ucsd.edu
<6e.1438.719.0N666787@cencore.com>
<1994Jul29.141840.16660@VFL.Paramax.COM>
Regulations require power companies to fix any emissions they produce.
I have had this happen in the past, and the first time they came right
out and traced the problem. The funny thing about this is that it was
not their equipt. that was causing the rfi. It was traced to a house
two doors away and a faulty fish tank heater!!
The second time I called them was in a different location. Everything
was great when I first moved in. It was winter and it was raining alot.
Then, when things started drying out, the noise started. 30 over S9 at
times. I traced it myself using a portable am radio to what I thought
was a power pole about 50 yards from my house. I comfirmed it was this
pole by pushing on it, and the static burst were in perfect timing with
the movment of the wires up top. I called them, and they came out, said
they could find nothing wrong. Of course I was not there to show them. I
called them back, and said "I know where the problem is". They came out
again and I showed them the trouble pole. The guy climbed up it, looked
at it for a few moments. Came back down and said "there nothing wrong".
I told him that thee was and that he should fix it. He said "Sorry, but
I dont have to do that!". I called the FCC and they came out a few days
later. I showed them what was going on, and within 2 weeks, not only was
the power company there fixing the static problem. But the cable company
was also there fixing leaks in their lines that was allowing me into
peoples tv's from 2 meters.
So, this goes to show that "YES THE WILL FIX IT, THEY HAVE TO!" (quate
from the fcc field rep on the phone)
If the power company refuses to help you, tell them you want to see
their "Broadcast license" to see if they can "transmit" radio
interference. Once they know you know the law, they will help you!
Or just say something like "If you cant fix it, I guess Ill have to get
the FCC to do it!" They will come running!
------------------------------
Date: Mon, 1 Aug 1994 17:08:42 GMT
From: psinntp!sunsrvr6!jdc@uunet.uu.net
Subject: 2m antenna on VW Golf/GTi, where?
To: ham-ant@ucsd.edu
In article <Ctnw4C.283@nntpa.cb.att.com>,
Andreas Meyer <ahm@hogpa.att.com> wrote:
>I own a 1985 Golf GTi and I've had a terrible time trying to find a spot
>on the car to mount an antenna for 2-meters. I'm currently using a
>Larsen mag-mount, but I'm getting tired of putting it on and taking it off.
>Also, I don't want to drill any holes!!!
> etc...
>
>Thanks,
>Andy
> -====--- Andreas Meyer, N2FYE ahm@hogpa.att.com
> --==---- AT&T Bell Laboratories, Holmdel NJ ..!att!hogpa!ahm
How about drilling through the roof in the dome light area? I don't
know about Golf's, but my old Rabbit's dome light was in the middle
of the roof, an ideal place for an antenna.
I just got done installing a Larsen 5/8 wave 2-meter antenna on our
'92 Saturn, again drilling through the dome light. Running coax
under the headliner wasn't too bad once the side trim was removed.
73...Jim N2VNO
------------------------------
Date: Sat, 30 Jul 94 20:28:05 EDT
From: ihnp4.ucsd.edu!agate!usenet.ins.cwru.edu!news.ysu.edu!malgudi.oar.net!hypnos!voxbox!jgrubs@network.ucsd.edu
Subject: Best HF mobile antenna??
To: ham-ant@ucsd.edu
Cecil_A_Moore@ccm.hf.intel.com writes:
> In article <F6y2Pc3w165w@jackatak.raider.net>,
> Jack GF Hill <root@jackatak.raider.net> wrote:
>
> >Forget "gain" as a consideration in mobile antennas... it does NOT
> >exist...
>
> Hi Jack, my S10 pickup is almost exactly a quarter-wave on 17m and I use
> a 13 ft. bumper mounted whip. By accident I discovered that I gain
> an extra 'S' unit when I point the front of the truck toward a station
> that previously was directly behind me. I modeled it using ELNEC and sure
> enough, it agreed with what I had experienced.
What you observed was 6 db. less loss... (Or whatever passes for an 'S'
unit these days.)
+--------------------------------------------------------------------------+
| Jim Grubs, W8GRT Voxbox Enterprises I _DO_ speak for Voxbox|
| jgrubs@voxbox.norden1.com 6817 Maplewood Ave. Enterprises. I own it. |
| Fido: 1:234/1.0 Sylvania, Ohio 43560 Home: 419/882-2697 |
| AMATEUR RADIO - The National Park of the Mind |
+--------------------------------------------------------------------------+
------------------------------
Date: Sat, 30 Jul 1994 02:13:27 GMT
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!swrinde!gatech!darwin.sura.net!isdnlin.mtsu.edu!perot.mtsu.edu!raider!theporch!jackatak!root@network.ucsd.edu
Subject: Best HF mobile antenna??
To: ham-ant@ucsd.edu
Cecil_A_Moore@ccm.hf.intel.com writes:
> In article <F6y2Pc3w165w@jackatak.raider.net>,
> Jack GF Hill <root@jackatak.raider.net> wrote:
> >However, the antenna requires getting out to change taps when moving
> >more than 6KHz of the frequency it is tuned for...
> Gosh Jack, it must be pretty hard "getting out to change the taps when
> moving..." :-)
Touche!!! Only after I saw your response did I see my gaff! Thanks for
returning the chuckle where I could enjoy it too! ;^)
Obviously (to me, anyway) I meant it was a pain to stop moving and
have to get out and move taps...
> One doesn't have to change taps if one uses a mobile antenna tuner.
I tried using one. However, the unit I tried had NO mechanism for a
bypass, and near resonance, it just swallowed signal... sure it would
work to flatten the shoulders of the SWR curve, BUT it did NOT, as you
allege it might, perform as well as I had hoped.
> When the SWR is less than 2/1 use the direct path through the tuner.
When I tired a tuner, it had NO bypass.
> You may lose a half a dB but you won't get wet.
That is NOT an insignificant improvement to operator comfort! ;^)
However, I must take issue...
> Your bug-catcher with a high SWR will radiate better than
> those low-Q, broad-band antennas with a low SWR!
...with the implication that the tuner solution would be even nearly
as good as the full bore resonant BugCatcher... it simply isn't so. I
suspect that the nature of the tuning, particularly coil location, and
the inductances involved "hide" some complex reactances that the tuner
simply masks...
I have used, and enjoyed VERY much, a "Texas Twister" (Henry Allen's
very excellent version of the Don Johnson, W6AQQ, DK-3 screwdriver
antenna.) The performance was excellent, though nowhere near as good
as the full-size BugCatcher. I traded the convenience of frequency
agility for the High-Q and performance of a tuned system. I am still
learning a great deal about these things, and would welcome anyone who
can and will enlighten me, but I hypothesize that the shortened nature
of a mobile antenna, and the tuning mechanisms involved in achieving a
workable match involve reactances and near fields which are "abnormal"
for antenna systems and tuners... Using a series of fairly good (65dB)
coax switches, I have tested antenna with tuner, antenna without
tuner, antenna off resonance with tuner, and the antenna set to
resonance without anything else was perceived by all stations in all
locations as stronger in varying degrees... The test was run blind, as
an A/B without a perceptable pause (Hey, if it works for an
optometrist, it must work for an antenna-trist! ;^) and the results
tabulated both with reported signal strengths, AND my received signal
strength during the report.
I have read Maxwell, and think I understand his work, and I am not
sure that my emperical findings are at conflict... has to do with the
nature of a conjugate match... ;^)
73,
Jack, W4PPT/Mobile (75M SSB 2-letter WAS #1657 -- all from the mobile! ;^)
+--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+
| Jack GF Hill |Voice: (615) 459-2636 - Ham Call: W4PPT |
| P. O. Box 1685 |Modem: (615) 377-5980 - Bicycling and SCUBA Diving |
| Brentwood, TN 37024|Fax: (615) 459-0038 - Life Member - ARRL |
| root@jackatak.raider.net - "Plus ca change, plus c'est la meme chose" |
+--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+
------------------------------
Date: 31 Jul 1994 06:23:04 GMT
From: ncar!asuvax!chnews!scorpion.ch.intel.com!cmoore@ames.arpa
Subject: Best HF mobile antenna??
To: ham-ant@ucsd.edu
In article <5189Pc1w165w@jackatak.raider.net>,
Jack GF Hill <root@jackatak.raider.net> wrote:
>Touche!!! Only after I saw your response did I see my gaff!
Wasn't really a gaff... I just chopped off your sentence at an opportune
location. :-)
>However, I must take issue...
>...with the implication that the tuner solution would be even nearly
>as good as the full bore resonant BugCatcher... it simply isn't so.
Didn't mean to imply that it was "as good as the full bore resonant
BugCatcher". What I meant to say was that the BugCatcher with an
antenna tuner is better than a Low-Q, broadband antenna without an
antenna tuner _under_all_conditions_, even a high SWR.
Let's say you have your BugCatcher tuned for an SWR of 1/1 on 7.25 MHz
and a broadband antenna is tuned for an SWR of 1/1 on 7.25. What I am
saying is that at a frequency where your BugCatcher has an SWR of 4/1 and
the broadband antenna has an SWR of 1.5/1, the BugCatcher will radiate
more RF with an antenna tuner than the broadband antenna will radiate
without an antenna tuner... I think that was the original question.
See, I'm on your side. Even when a BugCatcher is handicapped by an antenna
tuner, it is still better than the broadband antenna. After all, what is
more broadband than a 50 ohm resistor? Lowering the Q in order to make
an antenna broadband results in losses. I'm saying, don't lower the Q,
use an antenna tuner to make your transmitter happy unless you want
"to change the tap while moving...".
You can't beat the BugCatcher tuned to an SWR of 1/1. You also can't
beat the BugCatcher with an SWR of 4/1... you just have to make your
transmitter happy and one way is with an antenna tuner.
73, Cecil, KG7BK, OOTC (Not speaking for Intel)
------------------------------
Date: Mon, 1 Aug 94 16:33:27 -0500
From: news.delphi.com!usenet@uunet.uu.net
Subject: Comet CA-350DB
To: ham-ant@ucsd.edu
Has anybody had any luck getting this to work. It is a dual band
29 mhz and 52 mhz antenna. My friend has one and cant get it to radiate
worth a darn. SWR curves are goofy too.
Thanks...Dave
NF8R@DELPHI.COM
------------------------------
Date: Mon, 1 Aug 94 16:30:49 -0500
From: news.delphi.com!usenet@uunet.uu.net
Subject: Hygain Hytower-2
To: ham-ant@ucsd.edu
While we are on this subject. Would somebody please give me a short
technical description of how the Hytower works. I know it uses
some sort of stub decoupling, But, how long are the stubs
And is the part of tower above or below decoupled/radiating.
73...Dave
NF8R@DELPHI.COM
------------------------------
Date: Sun, 31 Jul 1994 04:18:11 GMT
From: netcomsv!netcom.com!netcom4!faunt@decwrl.dec.com
Subject: JPole fundamentals
To: ham-ant@ucsd.edu
OK, I think I've got the basics of "JPole" antennas. This is thrown
out for correction and discussion, so please follow up.
A JPole is an 5/8 or 1/2 wave monopole antenna, with a 1/4 wave
matching section. One leg of the antenna is 3/4 or 7/8 wave long, and
the other is 1/4 wave, shorted at together at one end. The coax is
connected enough above the shorted end to present the right impedance,
and it doesn't seem to matter which side the shield and center
conductor are connected. At least one version has the shield
connected to the shorted end and the center conductor capacitively
coupled to the longer section. There seems to be a belief that the
5/8 wave version gives more gain than the 1/2 wave version.
Ok, is this all true? Does anyone know if you really get more gain
from the 5/8 wave?
73, doug
------------------------------
Date: Mon, 1 Aug 94 02:07:00 -0500
From: ihnp4.ucsd.edu!agate!iat.holonet.net!wwswinc!barry.davis@network.ucsd.edu
Subject: New
To: ham-ant@ucsd.edu
VBARNET BBS is now carrying this conference.
--- Squish v1.01
* Origin: VBARNET * USA * (410)761-3406 or 922-8947 * PCB & OS/2 (1:261/1458)
------------------------------
Date: Sun, 31 Jul 1994 19:52:24 GMT
From: lll-winken.llnl.gov!overload.lbl.gov!agate!iat.holonet.net!vectorbd!jpll@ames.arpa
Subject: Q:SW car antenna?
To: ham-ant@ucsd.edu
Brad (bradb@netcom.com) wrote:
: I'd appreciate any suggestions on what to do for a *removable* form of
: shortwave antenna to use while in the car. I'd like to listen to my Sony
: SW100 while on LONG trips through the middle of more or less barren AM
: radio land.
Try a CB whip on the back of the car. Put a 9:1 balun at the feed. Run coax
to the radio.
--
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-Jim Lill- Vector Board BBS
jpll@vectorbd.com 716-544-1863/2645
wa2zkd@wb2psi.#wny.ny.usa.na GEnie: ZKD
------------------------------
Date: 1 Aug 1994 14:24:46 GMT
From: pendragon!jalonso@ames.arpa
Subject: Question: Powerlines surrounding Antenna
To: ham-ant@ucsd.edu
Hi,
I got a question that hopefully someone can answer or give insight.
Lets start with the background information. First, my receiver is a
Grundig Satellite 700. Second, my deed restriction doesn't allow antennas,
(sounds familiar). But third, I am surrounded by powerlines (see map below).
My friends says that the loud background noise I get is from the powerlines.
Currently, I have A quarter-wave dipole in my attic. It's made from 12 guage
insulated stranded copper wire with a R8 feedline. I know this is overkill for
a SWL, but eventually I want to get my license and get a HF rig.
My question is two-fold:
1) What is the best type of antenna and/or modification that I can do to
eliminate the background noise.
amd
2) Will the powerlines reduce my transmitting capabilities when I get my
HF rig?
MAP:
Powerlines
|
\ /
+++++++++++++++++++++++++++++++++++++++++++ <- Powerline
+
+
----- +
| ME | +
----- +
+
+
+
+
+ <- Powerline
Thanks!
Jose
------------------------------
Date: Mon, 01 Aug 1994 07:23:51 -0400
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!usc!elroy.jpl.nasa.gov!wp-sp.nba.trw.com!gatekeeper.esl.com!m21003.esl.com!user@network.ucsd.edu
Subject: Trade hf 5 band verticle 4 yaesu ft11r
To: ham-ant@ucsd.edu
Hi all, i have a new (unopened) maldol vk5jr 5 band verticle antenna, that
covers 10/15/20/40/80 mtrs. approx 20' with trap radials for limited space
installations. specs avail via fax. would like to trade for a yaesu ft11r
2mtr ht. any takers??? i'll ship ups u do the same. e-mail reply to
doug_huston@smtp.esl.com or call 408-738-2888 x5825 73's Doug kc6fry
--
"No man cam be condemned for owning a dog. As long as he has a dog, he has
a friend; and the poorer he gets the better friend he has." Will Rogers...
Comments are mine, not related to ESL.
------------------------------
Date: Sat, 30 Jul 1994 02:51:28 GMT
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!swrinde!gatech!darwin.sura.net!isdnlin.mtsu.edu!perot.mtsu.edu!raider!theporch!jackatak!root@network.ucsd.edu
Subject: What coax feed to use for 2m antenna
To: ham-ant@ucsd.edu
cropley@cbnewsf.cb.att.com (andrew peter.cropley) writes:
> Have you ever tried 9880? We had lots of this stuff laying around from
> an old ethernet network.
The cable itself is quite good for lower power applications (ethernet
is NOT a kilowatt kinda deal! ;^) *AND* the jacket is *NOT*
Ultraviolet resistant... The regular coaxial cables for outside use
have U/V resistant jackets that hold up, for a while, to U/V...
ethernet cable was made for indoor, NON-U/V environments, and so,
would have to be replaced regularly... other than that, it works
remarkably well...
73,
Jack, W4PPT/Mobile (75M SSB 2-letter WAS #1657 -- all from the mobile! ;^)
+--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+
| Jack GF Hill |Voice: (615) 459-2636 - Ham Call: W4PPT |
| P. O. Box 1685 |Modem: (615) 377-5980 - Bicycling and SCUBA Diving |
| Brentwood, TN 37024|Fax: (615) 459-0038 - Life Member - ARRL |
| root@jackatak.raider.net - "Plus ca change, plus c'est la meme chose" |
+--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+
------------------------------
Date: Sat, 30 Jul 1994 02:41:47 GMT
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!swrinde!gatech!darwin.sura.net!isdnlin.mtsu.edu!perot.mtsu.edu!raider!theporch!jackatak!root@network.ucsd.edu
Subject: What coax feed to use for 2m antenna
To: ham-ant@ucsd.edu
vinod@watson.ibm.com (Vinod Narayanan) writes:
> I want to put up the right coax-line for the feed
> just once, and connect the antenna using connectors. So,
>
> 1. What type of coax should I put up?
The best you can afford... 9913 would be good, but there are very good
coax available for less money... with lower performance and higher
attenuation.
> 2. What type of connectors should I use at the antenna end for
> coupling the long feedline with the (short) connecting coax from
> the antenna?
Well, several may jump up and yell about there being no difference
between a PL-259 and "N" connector performance, the major difference
being price.
There is a grain of truth to that, *BUT*
1) "N" connectors are weatherproof, the strongest recommendation I can
think of...
2) "N" connectors are *far* easier to assemble and install, the major
requirement being how well you measure! Gets my vote!
3) PL-259 connector, *PROPERLY INSTALLED* are the equal of the "N"
well into the gigahertz region -- Al, N1AL ran some tests on some
"upscale" Hewlett-Packard gear and confirmed this a year ago...
4) Not many can PROPERLY install a PL-259, which furthers the myth of
their poor performance, and really makes weather a problem.
I wouldn't use the "N" because of attenuation/loss, but I'd spend the
few bits more per connector for the weatherproofing... I did on my
mobile, and I have NEVER had moisture in the coax problems like others
who live in places where it rains... (No comments about empirical
evidence from desert dwellers! You *know* who you are! ;^)
73,
Jack, W4PPT/Mobile (75M SSB 2-letter WAS #1657 -- all from the mobile! ;^)
+--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+
| Jack GF Hill |Voice: (615) 459-2636 - Ham Call: W4PPT |
| P. O. Box 1685 |Modem: (615) 377-5980 - Bicycling and SCUBA Diving |
| Brentwood, TN 37024|Fax: (615) 459-0038 - Life Member - ARRL |
| root@jackatak.raider.net - "Plus ca change, plus c'est la meme chose" |
+--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+
------------------------------
End of Ham-Ant Digest V94 #245
******************************