QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940022.txt

Internet Message Format | 1994-11-13 | 20KB

Date: Thu,  3 Feb 94 04:30:19 PST
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #22
To: Ham-Ant


Ham-Ant Digest              Thu,  3 Feb 94       Volume 94 : Issue   22

Today's Topics:
                              60' sloper
                          Antenna pre-amps.
                      Are MFJ Antennas Any Good?
                       Biconical Antenna Design
                                BV2CH
                       Dipole supplies (3 msgs)
            How far wire antenna from power lines (2 msgs)
                     Ideas ? GAP Challenger DX-VI
                         mininec source code
                new Radio Communications mailing list
                             Quagi part 2
                RG-58 and Discone ant. problem at VHF
                          RS Rotor (2 msgs)

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: 31 Jan 94 20:14:00 -0500
From: blkcat!1-109-239-0![e-mail]
Subject: 60' sloper
To: [e-mail]

for sale with two baluns. 50' coax.... [phone].  $45.00

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

Date: Sun, 30 Jan 1994 16:11:34 GMT
From: agate!howland.reston.ans.net!newsserver.jvnc.net!raffles.technet.sg!ntuix!ntuvax.ntu.ac.sg![e-mail]
Subject: Antenna pre-amps.
To: [e-mail]

In article <[e-mail]>, [e-mail] (Dave Tiller) writes:
> [e-mail] wrote:
> : Hi,
>
> :     Can anyone tell me the disadvantages/advantages of using an antenna
> : pre-amp?
>
> Advantages: Better apparent noise figure since the coax attenuation is
> no longer a factor (for antenna mounted amps), much higher signal levels,
> inproved copy on waek signals.

    What about for non-masthead pre-amps? Got any good circuits?

73 de 9V Daniel

>
> Disadvantages: Your transmitter output must backwash thru the thing - either
> the amp itself must detect the inbound RF and switch itself away, or you
> must provide a switching relay and the appropriate signal to do it manually.
> Additional risk of lightning damage since you've got to run power up the
> coax or a separate cable, and now there's a sensitive little GasFET up there
> waiting for a strike.  Greater chance of front end overload on relatively
> strong signals (not an issue with an RF gain control.)
>
> --
> David Tiller        | Network Administrator    | Voice: [phone]       |
> [e-mail]        | Randolph-Macon College| Fax:   [phone]       |
> [e-mail]    | P.O. Box 5005        | This space for rent.        |
> ICBM: 37 45N 77 45W    | Ashland, Va 23005    |                             |

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

Date: 31 Jan 94 12:03:10 -0800
From: library.ucla.edu!csulb.edu!nic-nac.CSU.net!nic.csu.net!vax.sonoma.edu![e-mail]
Subject: Are MFJ Antennas Any Good?
To: [e-mail]

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
([e-mail])


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

Date: Sun, 30 Jan 1994 04:42:50 GMT
From: agate!library.ucla.edu!csulb.edu!nic-nac.CSU.net!usc!cs.utexas.edu!geraldo.cc.utexas.edu!slip-2-5.ots.utexas.edu![e-mail]
Subject: Biconical Antenna Design
To: [e-mail]

Does anyone have info on design parameters for a biconical antenna for use
on 30 to 88 Mhz for both transmit and receive? I have heard that this type
of antenna acn maintain a reasonable SWR over several octaves of bandwidth.

Maybe someone with military commo experience can help. The design needs to
be similar to a DOD OE-254 antenna.

Thanks.

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

Date: Tue, 1 Feb 1994 23:09:56 GMT
From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!cs.utexas.edu!oakhill![e-mail]
Subject: BV2CH
To: [e-mail]

 This is a testing from BV2CH.

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

Date: Sun, 30 Jan 1994 15:06:13 GMT
From: world![e-mail]
Subject: Dipole supplies
To: [e-mail]

In article <2ige7m$[e-mail]> [e-mail] (William E Van Horne) writes:
>
>
>
>Julian Macassey wrote:
>
>>        And finally the $64,000.00 question. What is recommended as
>>the best "rope" to hold up my cheesy antennas? It should be rot and UV
>>proof. Nylon I believe will rot in the sun, as will polyester. What is
>>the definative word? Any Plastics men on the net who can answer this?
>
>ANY organic material (plastics, hemp, human skin :-) ) is damaged by
>UV.  Plastics can be doped with "UV retardant" additives, but that only
>slows down the deterioration, it doesn't stop it.  The best "UV
>retardant" of all is carbon-black, a pigment that totally absorbs all
>light of all wavelengths.  All black plastic (I think) is loaded with
>carbon-black pigment, so that is the key.
>
>One source of black polyester rope is Synthetic Textiles, Inc., 2472
>Eastman Avenue, Bldg 21-22, Ventura, CA 93003, [phone].  I have
>never dealt with them, but received their literature.  For myself, I use
>plain nylon rope and replace it every couple of years.

I have two spools of dacron line from Synthetic Textiles. The product is
great, and the service was very good. Be sure to cut the rope with a hot
knife (effectively melting it) rather than cutting. This keeps the ends
sealed (same rule applies to any synthetic rope like nylon, etc.).


--
---------------------------------------------------------------
Daniel Senie                 Internet:     [e-mail]
Daniel Senie Consulting                    [e-mail]
508-365-5352                 Compuserve:   74176,1347

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

Date: Mon, 31 Jan 1994 13:45:33 GMT
From: netcomsv!netcom.com![e-mail]
Subject: Dipole supplies
To: [e-mail]

>One source of black polyester rope is Synthetic Textiles, Inc., 2472
>Eastman Avenue, Bldg 21-22, Ventura, CA 93003, [phone].

Another is Home Depot or practically any other hardware store.

Greg

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

Date: Mon, 31 Jan 1994 13:42:08 GMT
From: netcomsv!netcom.com![e-mail]
Subject: Dipole supplies
To: [e-mail]

In article <[e-mail]> [e-mail] (Julian Macassey) writes:
>
>    And finally the $64,000.00 question. What is recommended as
>the best "rope" to hold up my cheesy antennas? It should be rot and UV
>proof. Nylon I believe will rot in the sun, as will polyester. What is
>the definative word? Any Plastics men on the net who can answer this?

It may not be definitive, but among the riggers who work on tall ships
the ONLY type of line which they will trust with their lives is the
black polypropylene (often with an orange stripe) which truckers
use to secure their loads. If this line 'looks' good it generally *is*
good. This is in marked contrast to other types, which can look great
but fail abruptly under load, once exposed to the rigors of the atmosphere.

Greg

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

Date: 1 Feb 1994 15:19:57 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!howland.reston.ans.net!vixen.cso.uiuc.edu!ux2.cso.uiuc.edu![e-mail]
Subject: How far wire antenna from power lines
To: [e-mail]

Do any regulations exists that tell how far away the wire antenna should be
from the power lines?  I know that the proximity results in line noise,
so it is best to keep it as far away as possible.

Ignacy Misztal, NO9E
[e-mail]

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

Date: Tue, 1 Feb 1994 20:32:19 GMT
From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!usenet.ins.cwru.edu!agate!library.ucla.edu!csulb.edu!nic-nac.CSU.net!usc!elroy.jpl.nasa.gov!newncar!csn!col.hp.com!srgenprp!alanb@@.
Subject: How far wire antenna from power lines
To: [e-mail]

Ignacy Misztal ([e-mail]) wrote:
: Do any regulations exists that tell how far away the wire antenna should be
: from the power lines?  I know that the proximity results in line noise,
: so it is best to keep it as far away as possible.

You should call up your local Planning Department to get the scoop on
zoning regulations.

As far as safety goes, be sure that there is no way the antenna could ever
fall on the power lines, or that the power lines could ever fall on the
antenna.

AL N1AL

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

Date: Tue, 1 Feb 1994 15:50:40 +0000
From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!pipex!demon!dis.demon.co.uk!paddocks.demon.co.uk![e-mail]
Subject: Ideas ? GAP Challenger DX-VI
To: [e-mail]

Does anyone have any ideas please ?

I installed a GAP Challenger DX-VI antenna in the summer of 92 and it has
worked reasonably well up to a few months ago.  Although the match is still
about the same and it still hears pretty well I seem to be getting very
poor reports (if reports at all).  Friends using other verticals aroud this
location seem to get through to the stations I am calling but not me !

I've had the antenna down and checked connections but nothing seems to help.

Any ideas ?

Has anyone actually tried an A/B comparrison with the GAP and an
R7, HF6V or AP8 ?

I feel ready to junk the GAP and try something else.

--

+-------------------------------+------------------------------------------+
| Andrew Gawthrope G0RVM        | internet   : [e-mail] |
|                               | compuserve : 100113,3062                 |
+-------------------------------+------------------------------------------+

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

Date: 31 Jan 1994 19:55:23 GMT
From: library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!noc.near.net!sunfish.hi.com!brainiac.hi.com![e-mail]
Subject: mininec source code
To: [e-mail]

I found the source for mininec in the /pub/rander/NEC directory on
netcom.com.

Thanks to Ray Anderson WB6TPU for maintaining this site.

Steve Byan                                  internet: [e-mail]
Hitachi Computer Products (America), Inc.
1601 Trapelo Road                           phone: [phone]
Waltham, MA 02154                           FAX: [phone]

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

Date: Wed, 2 Feb 1994 23:15:48 GMT
From: dog.ee.lbl.gov!newshub.nosc.mil!news![e-mail]
Subject: new Radio Communications mailing list
To: [e-mail]

NRaD RADIO COMMUNICATIONS NETWORK

We are beginning a new mailing list for the
professional radio communications engineering
community.  rec.radio.amateur.* is a well
established source of information for radio
hobbyists, but it does not meet the needs
of many commercial, military, and academic
professionals.

Therefore, we are hoping that this mailing list
will somewhat fulfill this need.  Relevant topics
include:  radio propagation, antenna design,
hardware design, FCC regulations, industry trends,
parts suppliers, military requirements, and
so forth.  We would prefer that hobby-oriented
topics remain on the established newsgroups.

To subscribe, send a message to me at:
[e-mail]

I will add your name to the list and send you an
informational message about the operation of
the mailing list.  If you wish to unsubscribe,
send me a message, and I will remove your name from
the mailing list.

Brett F. Martin
Naval Command, Control, and Ocean Surveillance Center
Research, Development, Test, and Evaluation Division
(NRaD)
San Diego CA

.

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

Date: 2 Feb 94 21:19:48 GMT
From: [e-mail]
Subject: Quagi part 2
To: [e-mail]

I left one out :)

Center Frequency    432.000       # of Elements 15      Units are Cm
                  Length     Spacing   Boom Pos
Reflector         71.120      0.000      0.000
Driven Ele        67.628     17.780     17.780
Director #  1     29.845     13.335     31.115
Director #  2     29.686     27.940     59.055
Director #  3     29.528     14.859     73.914
Director #  4     29.369     22.225     96.139
Director #  5     29.210     22.225    118.364
Director #  6     29.051     22.225    140.589
Director #  7     28.892     30.480    171.069
Director #  8     28.734     30.480    201.549
Director #  9     28.734     28.575    230.124
Director # 10     28.575     29.210    259.334
Director # 11     28.416     23.336    282.670
Director # 12     28.257     31.432    314.103
Director # 13     28.099     34.925    349.028
 Total Length      3.490 M



end
        the views expressed here are the author's

C. Harper         [e-mail] or [e-mail]
KD4QIO
SPARTA Inc         [phone] x1216 voicemail
4901 Corporate Drive     [phone]       FAX
Huntsville AL 35805
"we have met the enemy and he is us."  w. kelly

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

Date: Tue, 1 Feb 1994 17:00:28 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!howland.reston.ans.net!spool.mu.edu!news.nd.edu!news1.oakland.edu!rcsuna.gmr.com!kocrsv01![e-mail]
Subject: RG-58 and Discone ant. problem at VHF
To: [e-mail]

>
> Also, don't rule out the possibility of front-end overload on the scanner
> when the discone is connected.  There may be nearby transmitter(s) that
> will cause the scanner's front-end to overload, therefore dsensitizing
> it.  The problem doesn't take place with the rubber duck due to the
> decrease in signal strength.
>
> My $0.02 worth,
> Keith Wolford
> N9IXG
> [e-mail]


Might a test for this be to place an attenuator box between the
rig and the discone, set the attenuator on "0dB", and then slowly
increase the attenuation and see if at some point the signals
magically become LOUDER, even though you are increasing attenuation?

i.e.
At some point you will have attenuated the "loud" nearby transmitter
to the point where it doesn't saturate the front-end and lets the
desired signal thru?

I suppose if you know what the theoretical dB difference between the
duckie and the discone was, this might be a good upper limit on
the attenuation levels you want to try.
--
James C. Bach              Ph: (317)-451-0455     The views & opinions expressed
Advanced Project Engr.     GM-NET: 8-322-0455     herein are mine alone, and are
Powertrain Strategy Grp    Amateur Radio: WY9F    NOT endorsed, sponsored, nor
Delco Electronics Corp.    Just say NO to UNIX!   encouraged by DE or GM.

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

Date: Tue, 1 Feb 1994 22:13:01 GMT
From: library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!usenet.ins.cwru.edu!news.csuohio.edu!vmcms.csuohio.edu![e-mail]
Subject: RS Rotor
To: [e-mail]

In article <2iegoo$[e-mail]>
[e-mail] writes:

>
>Does anyone have any experience with Radio Shack antenna rotors?  I can find
>[e-mail]
I use one for a Cushcraft ten-3, 10m beam.  I have a homebrew thrust
bearing several feet above it, made of an old mast-through rotor with the
innards removed.  It works ok, but I ruined 2, getting exchanges from
RS, before I found out that they can not be used continuous duty.  I
ruined one, with no load, indoors, brand new, just rotating it back and
forth steadily for about 20 minutes.  The motor in the control box got
too hot and the coil shorted I think.  You can look up the weight and
wind loading of the Ten-3 in the standard catalogs.

Now I'm careful to give it a few seconds rest in swinging back and forth
very far.   -------- Phil Emerson, AA8JO

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

Date: Mon, 31 Jan 1994 13:43:39 GMT
From: netcomsv!netcom.com![e-mail]
Subject: RS Rotor
To: [e-mail]

In article <2iegoo$[e-mail]> [e-mail] writes:
>Does anyone have any experience with Radio Shack antenna rotors?  I can find
>no information about load capacity for weight or wind-area of antennas, etc.
>I'm looking for a rotor for a 14 ele 2m beam I plan to build, and wondered
>if the RS offering might do.
>Thanks for your help!

Find a TV antenna at RS that has similar boom and element dimensions
to your beam. Find out what rotor they recommend for that. Buy it.

Greg

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

Date: 1 Feb 1994 17:49:21 +1100
From: unogate!news.service.uci.edu!usc!howland.reston.ans.net!agate!msuinfo!harbinger.cc.monash.edu.au!yarrina.connect.com.au!werple.apana.org.au!lsupoz.apana.org.au!sleeper![e-mail]
To: [e-mail]

References <[e-mail]>, <[e-mail]>, <[e-mail]>yarrina
Subject : Re: safety of HT antennas

In <[e-mail]> [e-mail] (Matthew Geier) writes:

>>Yes, I did think of this solution, although for mobile use when I'm on
>>a train it would not be so good since the antenna would always be
>>collecting bits of tree or tunnel or bridge or......

> Or 1.5KDC railway overhead..

Yes, that's the major problem. I doubt that the transmitter isolation
would stand up to 1500 volts DC being fed into it, and the received would
very definitely become plastic charcoal!


> Id go to the ocupational health and safety officer and present a case
>that useing these hand-helds in the cab next to ones head is a potential
>health risk, and that roof mounted attenna's should be fitted to all
>locomotives, and not just the select few that run interstate.
> Then you reduce the close emmissions to the times your are outside checking
>things.

This could be worthwhile pursuing, but of course with the new radio
system being progressively installed any action would be non-resultant.

> Not the best, but at least you have removed the situation where you are
>in a metal box, holding the annenna next to your head, with the RF bounceing
>around untill it finds a window..

Yeah - it's kind of like sitting in a microwave, except that the RF is
at UHF and not SHF. I never understood how these so-called communications
engineers worked out that we'd be able to get a decent ammount of RF
outside of the metalwork of the loco cabs. Most of the time when we're
on the older engines (hood units) the only way to get good signal levels in
and out is to stand outside on the walkway with the radio!

Craig, the Freight Raver.

--
          Craig Dewick [Freight Raver Craig] ([e-mail]).
                    - Swimming in the MUSIQUARIUM of Life -
 Always striving for a secure long-term future in an insecure short-term world.

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

End of Ham-Ant Digest V94 #22
******************************