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1994-11-13
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Date: Wed, 9 Feb 94 04:30:16 PST
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 #27
To: Ham-Ant
Ham-Ant Digest Wed, 9 Feb 94 Volume 94 : Issue 27
Today's Topics:
75 ohm twinlead
9913 for scanner use (was Re: RG-58 and Discone ant. problem at VHF (2 msgs)
??using HF moible ant. for home base station?
? HF Quad kits ?
Are MFJ Antennas Any Good?
Coax, Baluns & Dipoles
Effective Raditated Power? (2 msgs)
ELNEC & Modelling Wire Antennae
Job postings.
TEMPEST - Electronic Eavesdropping
Wind Load ???
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: 7 Feb 94 06:58:00 GMT
From: library.ucla.edu!agate!howland.reston.ans.net!xlink.net!fauern!rz.unibw-muenchen.de!claude@network.ucsd.edu
Subject: 75 ohm twinlead
To: ham-ant@ucsd.edu
rkarlqu@scd.hp.com (Richard Karlquist) writes:
>An article on the G5RV antenna mentions 75 ohm "transmitting"
>type twinlead for the 34 foot matching section. Can someone
>tell me where to buy this stuff?
Some years ago, there was such a product in the Amphenol catalog.
>What gauge wire is it
>and what type of plastic (polyethelene?)? What is the
>loss per 100 feet at HF?
If you cannot get the information, please ask me again. I will
try to find my old catalog.
--
Claude F. (claude@bauv106.bauv.unibw-muenchen.de)
This message may contain opinions which are not shared by my employer.
The facts can speak for themselves.
------------------------------
Date: Mon, 7 Feb 1994 04:35:27 GMT
From: library.ucla.edu!agate!spool.mu.edu!darwin.sura.net!fconvx.ncifcrf.gov!mack@network.ucsd.edu
Subject: 9913 for scanner use (was Re: RG-58 and Discone ant. problem at VHF
To: ham-ant@ucsd.edu
In article <2iu83tINNctr@abyss.West.Sun.COM> myers@cypress.West.Sun.COM writes:
>In article llc@ornews.intel.com, bmiller@landesk.intel.com (Brett Miller - Support Engineer) writes:
>>In article <2iopihINNa5o@abyss.West.Sun.COM> myers@pongo.West.Sun.COM (Dana Myers ) writes:
>>>In article <Pine.3.89.9401291735.A26656-0100000@comp> Peter Laws <plaws@comp.uark.edu> writes:
>>>>> A guy I know recently installed a Discone Antenna (R-S brand) and 50 ft of
>>>If you want low-loss coaxial cable in a 50 ohm system, use Belden 9913.
.
>>
>>I always get a kick when someone suggests spending $100+ for coax for use
>>with a no-gain $50 discone and a RS scanner. Chances are, moving the
>>scanner and attached wip antenna to the other side of the room will have
>>similar results.
>
Agree. Rather than cluttering up the group with this one word reply, I tried
to e-mail you, but the mail bounced (just incase you haven't got your return
address right - I couldn't ping or finger you either)
Joe Mack NA3T
mack@ncifcrf.gov
------------------------------
Date: 4 Feb 1994 19:36:29 GMT
From: metro!dmssyd.syd.dms.CSIRO.AU!dmsperth.per.dms.CSIRO.AU!uniwa!harbinger.cc.monash.edu.au!yeshua.marcam.com!news.kei.com!sol.ctr.columbia.edu!spool.mu.edu!olivea!koriel!@@munnari.oz.au
Subject: 9913 for scanner use (was Re: RG-58 and Discone ant. problem at VHF
To: ham-ant@ucsd.edu
In article llc@ornews.intel.com, bmiller@landesk.intel.com (Brett Miller - Support Engineer) writes:
>In article <2iopihINNa5o@abyss.West.Sun.COM> myers@pongo.West.Sun.COM (Dana Myers ) writes:
>>In article <Pine.3.89.9401291735.A26656-0100000@comp> Peter Laws <plaws@comp.uark.edu> writes:
>>>> A guy I know recently installed a Discone Antenna (R-S brand) and 50 ft of
>>>> RG 58 for his scanner. Problem: The rubber duck on the handheld unit, 20
>>>
>>>There's your answer right there: RG58 and UHF don't mix very well. I
>>>don't have the RS $3 Catalog near me, but I think you'll be surprised at
>>>the dB loss at UHF. And I don't recall the discone design having much,
>>>if any, gain.
>>>
>>>On my indoor discone, I use the RG8/M from RS which has less loss at the
>>>higher frequencies. You'll find a lot of folks who'll recommend RG6 for
>>>scanner use, too. (I don't use it 'cause it's ~70 ohm and I like to use
>>>my discone for my 2m HT).
>>
>>If you want low-loss coaxial cable in a 50 ohm system, use Belden 9913.
>>This is a partial-air dielectric coax, with about the same form factor
>>as RG-8.
>
>I always get a kick when someone suggests spending $100+ for coax for use
>with a no-gain $50 discone and a RS scanner. Chances are, moving the
>scanner and attached wip antenna to the other side of the room will have
>similar results.
Well, sure. But he didn't ask where to put his antenna; by the time I
commented on the question, it was about low-loss coax at VHF/UHF. Pardon
me if I was wrong.
Anyway, where do you spend $100+ for 50 feet of 9913? I bought a 100 foot
spool of brand new 9913 for $20 once. $100 would buy 50 feet of Andrews
Heliax. If you pay more than $40 for 50 feet of 9913, you're paying too
much.
>I'm not knocking 9913 or you Dana, but somtimes the pat Ham radio answers
>don't apply to low budget scanning. Also 9913 tends to be a little stiff
>for most people that want to swap coax/radios.
Well, golly, Brent, I'm really sorry. The question appeared to be "what is
a low loss coax for UHF?" The question did not appear to be "What can I
do without spending money to make my scanner better?".
---
* Dana H. Myers KK6JQ, DoD 466 | Views expressed here are *
* (310) 348-6043 | mine and do not necessarily *
* Dana.Myers@West.Sun.Com | reflect those of my employer *
* This Extra supports the abolition of the 13 and 20 WPM tests *
------------------------------
Date: 7 Feb 94 10:44:41 MDT
From: ihnp4.ucsd.edu!sdd.hp.com!swrinde!elroy.jpl.nasa.gov!usc!yeshua.marcam.com!zip.eecs.umich.edu!destroyer!ncar!csn!hellgate.utah.edu!cc.usu.edu!sltmw@network.ucsd.edu
Subject: ??using HF moible ant. for home base station?
To: ham-ant@ucsd.edu
In article <CKtJMs.LK5@ucdavis.edu>, szhall@chip.ucdavis.edu () writes:
> I am getting a HF mobile(HUSTLER 10-40 Meters) next for my car and I
> would like some feeling about using it for a home base ant. as well. I
> am using a dipole right now..Would it be hard to ground and whats its Db
> ? please fill me in any imformation you can give me..tns..Jeff N6MYF
>
I've used a Spider Multi-Band antenna for portable use several times...It makes
a great Field Day station. Get yourself a large square frying pan, and about
four 4ft ferring strips. Drill a few holes in the frying pan to mount the
antenna, and the ferring strips for support. Finally, cut as many ground
radials (You'll need 'em) as you can, and you are in business.....
(The whole setup cost me about 3 dollars, get the frying pan at a Goodwill
store)....
Good Luck!
--
-------------------------------------------------------------------------------
Daniel D Holmes " " - Marcel Marceau
Internet: SLTMW@CC.USU.EDU
AmprNet: N7NKR @ N7NKR.HOME.AMPR.ORG 44.40.1.43 [located in Salt Lake City]
N7NKR @ N7NKR.AMPR.ORG 44.40.12.10 [located in Logan]
------------------------------
Date: Mon, 7 Feb 1994 21:47:04 GMT
From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!uchinews!kimbark!khopper@network.ucsd.edu
Subject: ? HF Quad kits ?
To: ham-ant@ucsd.edu
Does anyone know of a HF Quad company ? How
about kits or parts for a 15M quad ? 2-3 el.
Thanks,
___________
Ken Hopper, N9VV | ___ |
HF biggot - PacTOR,RTTY,SSTV,CW |o o \_/ o o|
"CW Spoken here" |o o @ o o|
khopper@midway.uchicago.edu |___________|
------------------------------
Date: Sat, 5 Feb 1994 03:18:17 GMT
From: hearst.acc.Virginia.EDU!maxwell!jmm5h@uunet.uu.net
Subject: Are MFJ Antennas Any Good?
To: ham-ant@ucsd.edu
butler@vax.sonoma.edu writes:
> I'm considering ordering a couple antennas from MFJ - specifically
> the 5/8 2m base (1750) and the 5/8 2m moblie (1728). I'd like to
> hear about any experiences, comments, or suggestions that might help
> make my decision.
>
> Thanks,
> -Bob Butler, KE6EHO
> (butler@sonoma.edu)
>
I just bought the MFJ scanner antenna (cellular
lookalike) for my bc350. It's a mag mount w/ so-239
connector. It works better than any mag mount I've had. I
plan on ordering another one to use the whip in a chassis mount
3/8x24 antenna I have on the roof of my truck for it's
scanner. I'd say thumbs up.
------------------------------
Date: Tue, 8 Feb 1994 22:48:46 GMT
From: agate!howland.reston.ans.net!spool.mu.edu!olivea!apple.com!gallant.apple.com!dfrancis.apple.com!user@network.ucsd.edu
Subject: Coax, Baluns & Dipoles
To: ham-ant@ucsd.edu
I'm a vetran user of J poles and base loaded monopoles fed with coax
on VHF, and am considering building a vertical dipole for 2 meters.
I've briefed the antenna and feed line chapters in the ARRL handbook,
but am undecided about feeding a dipole with coax and a balun vs.
designing an antenna with a built in matching section (J pole)
I'd like to build a simple vertical with two pieces of 3/4" copper or
aluminum pipe - "center" fed with coax. Do I need a balun or would it
be just as good to do a an "unfolded" J pole? 1/4 wave matching section,
co-linear with a 3/4 wave section? (Is this not a vertical Zepp?)
Other suggestons welcome.
-df
------------------------------
Date: 4 Feb 1994 23:54:42 GMT
From: olivea!koriel!male.EBay.Sun.COM!uranium!raymonda@uunet.uu.net
Subject: Effective Raditated Power?
To: ham-ant@ucsd.edu
In article 2ipbbbINNq2u@news.d.umn.edu, tstein@monolith.d.umn.edu (Tom Stein) writes:
.>I have a quick question:
.>
.>Say I have 40 watts coming out of the back of my radio. My feedline is
.>1.4dB per 100 ft. I have 100 feet of feedline... Then my antenna, a 11 el.
.>beam has 11dB gain on it. Can someone tell me what the effective radiated
.>power of my system would be? And a formula would help....
.>
.>Tom Stein (N0UJK)
.>
P2=40 watts P1=erp
Gain in dB = +11dB -1.4dB = +9.6dB
dB(power) = 10*log(P1/P2)
so: 9.6=10*log(P1/P2)
.96=log(P1/P2)
(P1/P2)= 10^.96
(P1/P2)=9.12
(P1/40) = 9.12
P1 = 364.8 watts effective radiated power
Ray WB6TPU
----------------------------------------------------------------------------
This response does not represent the official position of, or statement
by, Sun Microsystems Incorporated. The above data is provided for informational purposes only. It is supplied without warranty of any kind.
----------------------------------------------------------------------------
/\
\\ \
\ \\ /
/ \/ / / Raymond E. Anderson
/ / \//\ Signal Integrity Engineer
\//\ / / Sun Microsystems
/ / /\ / 2550 Garcia Ave. MS MIL04-16
/ \\ \ Mountain View, CA 94043-1100
\ \\
\/ (408) 276-5224
(408) 956-0492 fax
raymond.anderson@Sun.Com
------------------------------
Date: Thu, 3 Feb 1994 19:15:23 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!cs.utexas.edu!howland.reston.ans.net!europa.eng.gtefsd.com!emory!wa4mei.ping.com!ke4zv!gary@network.ucsd.edu
Subject: Effective Raditated Power?
To: ham-ant@ucsd.edu
In article <2ipbbbINNq2u@news.d.umn.edu> tstein@monolith.d.umn.edu (Tom Stein) writes:
>I have a quick question:
>
>Say I have 40 watts coming out of the back of my radio. My feedline is
>1.4dB per 100 ft. I have 100 feet of feedline... Then my antenna, a 11 el.
>beam has 11dB gain on it. Can someone tell me what the effective radiated
>power of my system would be? And a formula would help....
Ok, you have +11db of antenna gain (in the main lobe) and -1.4db of loss
in the coax. So the system gain is 11+(-1.4)=9.6db, db add, you just have
to pay attention to the sign. Now the db power ratio formula is
db=10*log(P1/P2)
We can use a little algebra and come up with
ERP=Pt*10^(db/10)
In your case, 40*10^(.96)=364.8 watts ERP.
Gary
--
Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244 | |
------------------------------
Date: 8 Feb 94 14:48:35 GMT
From: news-mail-gateway@ucsd.edu
Subject: ELNEC & Modelling Wire Antennae
To: ham-ant@ucsd.edu
Howdy! I recently acquired ELNEC and would like to share experiences
with others on modelling beverages, bobtail curtains and other wire
type arrays.
73 de Walt - K2WK
------------------------------
Date: Thu, 3 Feb 1994 11:36:16 -0500
From: rsg1.er.usgs.gov!darwin.sura.net!howland.reston.ans.net!europa.eng.gtefsd.com!fs7.ece.cmu.edu!news.sei.cmu.edu!bb3.andrew.cmu.edu!andrew.cmu.edu!cb1p+@seismo.css.gov
Subject: Job postings.
To: ham-ant@ucsd.edu
RedZone Robotics, Inc. A six year old robotics startup (and a spinoff
from CMU Field Robotics) located in Pittsburgh PA is looking for more
people in our continued expansion.
We are looking for Mechanical engineers with experience in
automated/controlled machine design. Electrical engineers with
Control systems experience. Software engineers with Real time control
experience.
All candidates should have at least a BS and some level of experience
in the field of robotics. (Or else a WHOLE LOT of exp. ;-) )
Generalists (multidisciplinary folks) are preferred.
For more information e-mail me or send your resume to:
Christopher Beasley
Control Systems Engineer E2
RedZone Robotics, Inc.
Pittsburgh, PA 15222
If you make it past the first cut you will definitely hear from us by
letter. All e-mail will be answered.
E-mail is the preferred method for initial contacts.
------------------------------
Date: 6 Feb 1994 20:56:31 -0800
From: ucsnews!newshub.sdsu.edu!usc!howland.reston.ans.net!spool.mu.edu!news.clark.edu!clark.edu!not-for-mail@network.ucsd.edu
Subject: TEMPEST - Electronic Eavesdropping
To: ham-ant@ucsd.edu
Re: the government prohibits use of tempest technology.....
Boeing surplus in Seattle was selling tempest housings for computers a
year or two ago. They were pretty cheap too.
Rick
------------------------------
Date: 7 Feb 1994 16:29:45 GMT
From: library.ucla.edu!csulb.edu!nic-nac.CSU.net!usc!howland.reston.ans.net!vixen.cso.uiuc.edu!newsrelay.iastate.edu!news.iastate.edu!kenman@network.ucsd.edu
Subject: Wind Load ???
To: ham-ant@ucsd.edu
The specs on my antenna state the following.
Wind load: 2.25 sq. ft.
What does this mean? (I know it relates to wind and antennas falling to the
ground, but what is it "exactly").
Tnx
Ken
--
Ken Anderson N0ZEM Kenman@iastate.edu PH: 515.294.8996
126 Soil Tilth Bldg., Iowa State University, Ames, Iowa 50011
------------------------------
End of Ham-Ant Digest V94 #27
******************************