QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940169.txt

Internet Message Format | 1994-11-13 | 14KB

Date: Sat,  4 Jun 94 04:30:14 PDT
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #169
To: Ham-Ant


Ham-Ant Digest              Sat,  4 Jun 94       Volume 94 : Issue  169

Today's Topics:
                        Antennas on Indy Cars
                            Balun question
                             Dipole help
                  Opinion on Alpha-Delta SWL sloper
                   stationmaster radomes wear out!
                Vertical antenna mathematical modeling
                  VHF/UHF Antennas on Jeep (2 msgs)
            Want to hear your experience with AEA Isoloop.

Send Replies or notes for publication to: <[e-mail]>
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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: 3 Jun 1994 13:51:34 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!europa.eng.gtefsd.com!news.msfc.nasa.gov!news.larc.nasa.gov!sirius.larc.nasa.gov![e-mail]
Subject: Antennas on Indy Cars
To: [e-mail]

I was whatching the Indy 500 and noticed that most of the cars had little antennas on them.  I guess for communications, data telem, and video.

Can anyone tell me more about these systems.

Thanks,
Jeff Case

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Date: Fri, 3 Jun 1994 13:30:31 GMT
From: world![e-mail]
Subject: Balun question
To: [e-mail]

In article <2sl2du$[e-mail]> [e-mail] (Cecil A. Moore -FT-~) writes:
>[e-mail] wrote:
>
>: I have an 80m dipole with a Van Gordon 1:1 balun at the feed point, with
>: Brian n8wrl (soon to be /ag)
>
>Hello again, Brian. I forgot to ask what is the power rating of your Van
>Gordon balun and how much power are you running?
>
>Also, a balun that has low DC resistance bleeds static electricity off
>the antenna which is a very good feature in my extremely high static

Some balun designs do this.

>electricity environment here in Arizona. When I used to run a G5RV with
>a choke balun, I could hear arcing inside my transceiver because of
>static electricity on the antenna.

Another approach to bleeding off the static, especially if youare using
a choke balun, is to use a non-DC-passive lightning/surge protector. I
use ones made by Industrial Communications Engineers. Basically they
contain a capacitor to conduct the RF signal across, a coil from the
antenna side to ground (and shield) to bleed off the static, and a gas
discharge tube from center to ground, just in case the lightning
gets near... Polyphaser makes similar units.

I have had very good luck with current baluns formed from a number of
ferrite cores placed around the coax at or near the feedpoint. I use
this approach on antennas with properly matched feedpoints as well, and
it does seem to help cut the amount of RF wandering down the feedlines.
I have at times also placed ferrites on the coax lines in or near the shack as
well, further reducing the likelihood of RF coming back into the shack
on the shields.

Dan N1JEB
--
---------------------------------------------------------------
Daniel Senie                 Internet:     [e-mail]
Daniel Senie Consulting                    [e-mail]
508-779-0439                 Compuserve:   74176,1347

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Date: Fri, 3 Jun 1994 13:33:10 GMT
From: ihnp4.ucsd.edu!usc!nic-nac.CSU.net!charnel.ecst.csuchico.edu!yeshua.marcam.com!news.kei.com!world![e-mail]
Subject: Dipole help
To: [e-mail]

In article <2sl80m$[e-mail]> [e-mail] (Roy W Lewallen) writes:
>I wrote:
>
>>. . . In all modern rigs I know of, the AGC can't be disabled. . .
>
>I stand corrected! Some modern rigs DO permit disabling of the AGC.
>At least the TS-930 and FT-990 have this capability. Thanks to N4ZR and
>KD1ON for correcting me.
>
>Roy Lewallen, W7EL
>[e-mail]
>

On all the ones I've used that allow the AGC to be turned off, you also loose
the S-meter, so it is still tough to discern that 2dB difference! (depends
solely on how well your hearing works).

Dan N1JEB
--
---------------------------------------------------------------
Daniel Senie                 Internet:     [e-mail]
Daniel Senie Consulting                    [e-mail]
508-779-0439                 Compuserve:   74176,1347

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

Date: Fri, 3 Jun 1994 13:26:06 GMT
From: ihnp4.ucsd.edu!swrinde!howland.reston.ans.net!news.moneng.mei.com!uwm.edu!news.doit.wisc.edu!saimiri.primate.wisc.edu!relay!relay.nswc.navy.mil![e-mail]
Subject: Opinion on Alpha-Delta SWL sloper
To: [e-mail]

In article <[e-mail]> [e-mail] (Terry Florek) writes:

   Anyone out there have any experience with the Alpha-Delta sloper
   antenna for SWL reception??

   Terry Florek  WB9QDM
   AT&T Consumer Products Labs, Indianapolis, Indiana

Check out the RDI White Paper "RDI Evaluates popular outdoor antennas". The
paper covers the Alpha-Delta sloper, Eavesdropper and some homemade Inverted-L
antennas. The paper concludes "Sloper provides excellent and unusually flexible
performance at a price well within the reach of the fastidious listener...".
The paper speaks very highly of the antenna.

-= stan     [e-mail]

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

Date: 3 Jun 1994 14:49:05 GMT
From: ihnp4.ucsd.edu!swrinde!howland.reston.ans.net!news.cac.psu.edu!news.pop.psu.edu!psuvax1!news.cc.swarthmore.edu!netnews.upenn.edu!eniac.seas.upenn.edu![e-mail]
Subject: stationmaster radomes wear out!
To: [e-mail]

In article <duffyfr-020694215700@134.174.41.129> [e-mail] (Frank H. Duffy, M.D.) writes:
>I recently asked for help to figure out why two Sincalir stationmaster
>repeater antennas(2M & 220) had both developed hi SWR and were leaking
>water down into the pigtail.  Well, we recently removed the two antennas
>and they both showed the same incredible finding.  The outer shiny white
>plastic coating of the radome was completely gone.  The middle layer of
>fibreglass wrapping was exposed!  Looks like 4 years of central Vermont
>wind at just under 2000'(both top mounted) had sufficient abrasive strength
>to strip off the outer porotective coat and allow water in!  I had never
>heard of this.  Does this happen at all repeater sites?  Is the Sinclair
>radome not as strong as other radomes (Celwave, etc)?

We have a 10dB UHF Sinclair on top of one of the high rises here in
Philadelphia.  It's been up since 1985, and has basically no paint left,
and the fiberglass is starting to fray.  I've been unhappy with the antenna
for this reason, and for other reasons.

I also have a Phelps-Dodge PD455 SuperStationmaster on top of an
adjacent building (three buildings, all same height).  It's been up
since 1978 and is in much better shape than the Sinclair.  I also have
a PD455 on top of a mountain outside of Philadelphia, and a PD400
on top of a mountain in the central part of the state and have had no
problems with them whatsoever.  I've also had good luck with DB Products
sticks, although I understand that they won't cut ham-band antennas
any more (they only pre-cut the commercial bands).

I'll stick with Celwave.  I've had miserable experience with Sinclair
and Antenna Specialists, and generally poor results with Diamond and
Comet antennas.  The Diamond and Comet antennas performed well, but
did not hold up on the mountaintops, and weren't DC grounded at the tips.

Depending on how bad your stick is, you may or may not be able to salvage
it.  I use a plastic marine paint to re-paint old sticks.  I don't remember
the name, but it wasn't cheap.  It's intended to be used on fiberglass,
and has no metal content.  I've heard of other techniques, but I've had
good luck with this paint.

                            --- Jeff
--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 Jeff DePolo  WN3A              Twisted Pair: [phone]H  387-3059W
 [e-mail]    RF: 443.800+ MHz   442.400+ MHz   24.150 GHz

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

Date: Fri, 3 Jun 1994 18:01:14 GMT
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!howland.reston.ans.net!news.moneng.mei.com!uwm.edu!mixcom.com![e-mail]
Subject: Vertical antenna mathematical modeling
To: [e-mail]

Anyone know of any PC compatible software for mathematical
modeling of vertical antennas?  I'm looking for radiation
patterns, SWR across frequency range, the works.  Also,
any recommendations and text books with detailed math on
the theory behind antenna radiation would help as well.

Please reply via Email.  Thanks.  73.

--
  /`-_           [e-mail]  |  Vote Libertarian!
 {     }/                                 |
  \    /      N9SQB, ARRL, Amateur Radio  |  Call 1-800-682-1776
   |__*|   N9SQB @ WA9POV.#MKE.WI.USA.NA  |  for more information.

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

Date: 3 Jun 1994 15:17:28 GMT
From: ihnp4.ucsd.edu!usc!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!col.hp.com!fc.hp.com!news.lvld.hp.com![e-mail]
Subject: VHF/UHF Antennas on Jeep
To: [e-mail]

I'm looking for anyone's experiences in mounting 2m, 440 and/or dual
band antennas on CJ's or Wranglers.  This particular Wrangler will be a
hard top, but the top will come off for summers so a roof mount with
some sort of ground plane installed underneath is out.  I plan on
installing a dual band mobile in the Jeep.  Any experiences with what
worked and what didn't for both antenna type and mount/location on this
sort of vehicle with this kind of rig would be greatly appreciated.


Scott Turner  KG0MR  [e-mail]

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

Date: 3 Jun 94 23:47:32 GMT
From: dog.ee.lbl.gov!ihnp4.ucsd.edu!usc!sdd.hp.com!col.hp.com![e-mail]
Subject: VHF/UHF Antennas on Jeep
To: [e-mail]

Scott Turner ([e-mail]) wrote:
: I'm looking for anyone's experiences in mounting 2m, 440 and/or dual
: band antennas on CJ's or Wranglers.  This particular Wrangler will be a
: hard top, but the top will come off for summers so a roof mount with
: some sort of ground plane installed underneath is out.  I plan on
: installing a dual band mobile in the Jeep.  Any experiences with what
: worked and what didn't for both antenna type and mount/location on this
: sort of vehicle with this kind of rig would be greatly appreciated.


: Scott Turner  KG0MR  [e-mail]

  If a ground plane is problem, try using antennas that don't require
  a ground plane such as a 1/2 wave. Larson makes a 1/2 wave 2 Meter
  antenna, Diamond makes a dual-band antenna that is 1/2 wave on 2M
  and stacked 5/8 waves on 70 cm.

Bob Witte / [e-mail]  / Hewlett Packard PMO / KB0CY  / [phone]

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

Date: Fri, 3 Jun 1994 12:24:58 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!csulb.edu!csus.edu!netcom.com![e-mail]
Subject: Want to hear your experience with AEA Isoloop.
To: [e-mail]

In article <[e-mail]> [e-mail] writes:
>Hello:
>I am presently considering buying an AEA Isoloop for HF. Does someone here
>have  experience with this antenna? Please let me know about the effectiveness
>of this antenna for HF, if used in an apartment balcony on the third floor.

Mine was in the attic of the second floor, probably the equivalent
height, and the structure was wood.

The effectiveness is beyond your wildest dreams. It is close to the ideal
antena for the urbanite, as it also does a fine job of NOT receiving the
broadband noise which is characteristic of such surrondings.

BTW, if it's on the balcony, you must make sure that nobody can touch
it. It's a voltage antenna, and the RF burns will be painful and severe.

The standard tuning device is worse than useless IMHO. The deluxe automatic
tuner has gotten mixed reviews, but is probably better. Mine was in use
prior to that, and rather than trying to tune for peak noise, I used the
cheapest MFJ SWR analyzer on a coax switch, zero-beated the analyzer
signal with the desired frequency in the station receiver, then set the
loop for 1:1 SWR. All this took less time than it takes to write it down.

Greg

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

Date: 3 Jun 94 17:18:05 GMT
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!howland.reston.ans.net!math.ohio-state.edu!cyber2.cyberstore.ca!nntp.cs.ubc.ca!alberta!atha!aupair.cs.athabascau.ca![e-mail]
To: [e-mail]

References <2sgmee$[e-mail]>, <2sibk7$[e-mail]>, <2sim2s$[e-mail]>n
Subject : Re: Grid Dip Oscillator or Noise Bridge?

[e-mail] (Jeff DePolo) writes:

>The MFJ noise bridge isn't too bad, but it isn't great either.  The
>lettering on the front panel corresponds to values hand-written on
>the bottom of the unit.  It takes a lot of good guessing to really
>know what you're reading on the dials.  Quality is about the same
>as other MFJ stuff - mediocre at best.

You can get some (say) 5% carbon resistors and make your own R scale
markings that will be at least as good as the factory ones :).

regards,
Ross ve6pdq
--
Ross Alexander VE6PDQ    [e-mail],
[phone]        [e-mail]

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

End of Ham-Ant Digest V94 #169
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