QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940261.txt

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

Date: Mon, 15 Aug 94 04:30:13 PDT
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #261
To: Ham-Ant


Ham-Ant Digest              Mon, 15 Aug 94       Volume 94 : Issue  261

Today's Topics:
                      ??Loop or dipole ..BEST??
                    Aluminum suppliers... (2 msgs)
                 Ever see a black tribander? (3 msgs)
         Ever see a black tribander? or how to keep ice away.
                      Multiple Guess Code Exams
                      RG58 versus Thin Ethernet
               Should feedline lenght change the VSWR?
                             tunor humor

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Archives of past issues of the Ham-Ant Digest are available
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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: 14 Aug 94 13:03:23 GMT
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!howland.reston.ans.net!europa.eng.gtefsd.com!newsxfer.itd.umich.edu!nntp.cs.ubc.ca!alberta!atha!aupair.cs.athabascau.ca![e-mail]
Subject: ??Loop or dipole ..BEST??
To: [e-mail]

[e-mail] (Jim Grubs, W8GRT) writes:

>I recommend connecting the ends together via capacitors.

Why?

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

Television is chewing gum for the eyes. -- Frank Lloyd Wright

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Date: 12 Aug 1994 22:30:30 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!csulb.edu!nic-nac.CSU.net!charnel.ecst.csuchico.edu!yeshua.marcam.com!news.kei.com!ssd.intel.com!chnews!scorpion.ch.intel.com![e-mail]
Subject: Aluminum suppliers...
To: [e-mail]

>From article <[e-mail]>, by [e-mail] (Marc DePaul):
>> Do you know of supplier names (and phone numbers) that supply
>> 2-3" diameter aluminum tubing?  I'm looking to make upwards
>> of a 30' boom length.

In article <[e-mail]>,
Ed Ingraham          <[e-mail]> wrote:

>Try asking local electrical supply houses about aluminum conduit.
>I've seen some about 1-1/2 or 2" OD in use as an antenna mast.

>--Ed, WX4S

Just my $0.02 worth here.  I would stay away from aluminum conduit
for any and all antenna projects.  It is much too soft and malleable.
It was designed to be bent around corners, after all.  I used it for
an antenna mast and found a perfect 90-degree bend in it after a
West Texas windstorm.

You really want to use aluminum tubing with the right characteristics.
I second RK's suggestion of Texas Towers in that the material they
offer is specifically designed for structural applications.  However,
if you take the same specification (T6-6061?) to a local supplier,
you will get the same stuff.

Jim Bromley, W5GYJ  <[e-mail]> (My *own* opinion!)

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

Date: 12 Aug 1994 17:43:50 GMT
From: portal.com!sdd.hp.com!hpscit.sc.hp.com![e-mail]
Subject: Aluminum suppliers...
To: [e-mail]

In article <[e-mail]>,
Ed Ingraham          <[e-mail]> wrote:
>From article <[e-mail]>, by [e-mail] (Marc DePaul):
>> Do you know of supplier names (and phone numbers) that supply
>> 2-3" diameter aluminum tubing?  I'm looking to make upwards
>> of a 30' boom length.
>
>Try asking local electrical supply houses about aluminum conduit.
>I've seen some about 1-1/2 or 2" OD in use as an antenna mast.
>
>--Ed, WX4S
>

Again, let me plug Texas Towers.  They sell aluminum cheaper than
electrical conduit stores, agricultural irrigation pipe stores,
and general purpose aluminum jobbers.  MUCH cheaper (3 to 10 times
lower.)  This is because they buy a mill run (10,000 feet) of each
size directly from the manufacturer.  They give even bigger discounts
if you buy 1000 feet.

I have no connection with Texas Towers except as a customer.

Rick N6RK
[e-mail]

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Date: 11 Aug 1994 18:39:25 GMT
From: ihnp4.ucsd.edu!ucsnews!newshub.sdsu.edu!nic-nac.CSU.net!usc!howland.reston.ans.net!gatech!udel!news.udel.edu!diusys![e-mail]
Subject: Ever see a black tribander?
To: [e-mail]

Pete Rossi ([e-mail]) wrote:
: After one of the big ice storms that hit here last winter, everything was
: coated with 1/4" of ice but when the sun came out the next morning, all of the
: ice on the BLACK COAX connected to my wire antennas was gone(!) within a couple
: hours.  But the ice on the trees, wires, shiny aluminum tubing and most
: everything else stayed around for 2 days!  So I am thinking of spray painting
: any future wire and aluminum that goes in the air FLAT BLACK to help melt the
: ice faster.  Something to think about, eh?  Anyone ever see a black tribander?
: Actually I think it would look neat.

: Comments?

I remember reading a magazine article _many_ years ago where a ham wrapped
electrical tape around the elements of his HF yagi to protect it from
the elements.  He lived near the ocean (fla, I think) and this kept the
aluminum underneath like new, rather than being eaten away from the salt
spray.
Never tried it myself.

73,  Dave  WA3U

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

Date: Sun, 14 Aug 94 00:47:57 CST
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!overload.lbl.gov!agate!iat.holonet.net!vulcan![e-mail]
Subject: Ever see a black tribander?
To: [e-mail]

[e-mail] (Richard Karlquist) writes:

> In article <32dr8t$[e-mail]>,
> Dave Dabell <[e-mail]> wrote:
> >Pete Rossi ([e-mail]) wrote:
> >: After one of the big ice storms that hit here last winter, everything was
> >: coated with 1/4" of ice but when the sun came out the next morning, all of
> >: ice on the BLACK COAX connected to my wire antennas was gone(!) within a c
> >: hours.  But the ice on the trees, wires, shiny aluminum tubing and most
> >: everything else stayed around for 2 days!  So I am thinking of spray paint
> >: any future wire and aluminum that goes in the air FLAT BLACK to help melt
> >73,  Dave  WA3U

When I moved to Chicago six years ago, the local hams strongly urged
me to paint my rotor flat black to help prevent it from freezing up!
I followed their advice, and it survived 3 winters without a hitch!
I believe it would work. The paint should be selected to maximize it's
heat collection properties. I just went for any old flat black, but was
advised later that some paints were better than others.

Living in the heart of DIXI now, don't worry about that problem too much.
Guess we need to paint 'em silver to reduce damage due to heat!

73

--
  Dennis T. Dease         internet - [e-mail] (or [e-mail])
  Pelham, Alabama, USA        packet radio - [e-mail]

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

Date: 13 Aug 1994 04:23:44 GMT
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!gatech!newsxfer.itd.umich.edu!zip.eecs.umich.edu!yeshua.marcam.com!news.kei.com!ssd.intel.com!chnews!scorpion.ch.intel.com![e-mail]
Subject: Ever see a black tribander?
To: [e-mail]

In article <[e-mail]>,
Pete Rossi <[e-mail]> wrote:

>So I am thinking of spray painting
>any future wire and aluminum that goes in the air FLAT BLACK to help melt the
>ice faster.  Something to think about, eh?
>Pete Rossi - WA3NNA                  [e-mail]

Hey Pete, good idea, and any physics student will tell you that black
bodies radiate better at night than when the sun is shining on them.

:-)  73, Cecil, KG7BK, OOTC  (Not speaking for Intel)


--
 Intel, Corp.
 5000 W. Chandler Blvd.
 Chandler, AZ  85226

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

Date: 14 Aug 1994 06:08:14 -0500
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!europa.eng.gtefsd.com!sundog.tiac.net!news.sprintlink.net!bga.com!bga.com![e-mail]
Subject: Ever see a black tribander? or how to keep ice away.
To: [e-mail]

>So I am thinking of painting my tribander..........etc.

There is a way to keep ice from building up on antennas.  In the
May/June 1994 (vol.22, No. 3) issue of the National Contest Journal
(NCJ)  K3ZJ wrote an article about a preventing antenna icing.

In this article he talks about a hydrophobic paint - made
just for keeping ice from forming on most materials including
aluminum and steel.

by the Vellox Corp. 100 Park St., Ayer, MA 01432 ph. 508-772-6302.

They sell a kit of primer and paint that will cover 20-30 sq feet
for $40.  They also sell the primer by the gallon - good for 350-400
sq. feet at $92/gal.  The top coat will cover 90-120 sq. feet per
gallon and costs $77.

The kit might be the answer for most ham antenna farms.


george
wb5vzl
[e-mail]
austin, tx

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

Date: 11 Aug 94 17:34:30 -
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!cs.utexas.edu!asuvax!ennews!wierius!nighthawk!1-114-24-0![e-mail]
Subject: Multiple Guess Code Exams
To: [e-mail]

In a message of <10 Aug 94  08:22:51>, [e-mail] (1:114/3636)
writes:

 cA>Over all I was most impressed with the multiple choice cw exam.  It
 cA>seem to test both your on-air experience (e.g. even it I didn't copy
 cA>the manufacture correctly, knowing who makes TS-, FT-, etc, would have
 cA>helped) as well as your conversational cw instead of informational cw.
 cA>Just being able to copy call signs, city, state, and numbers is no
 cA>longer useful to pass the code exams.

Andrew, glad that you think that it is a reasonable test.  I passed my 13wpm in
March and with no other tests since my 5wpm to compare it to, thought that
maybe I was slacking some on the 13.  You helped me feel a little better about
my accomplishment in passing.

73 de Mike KB7DJE


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Date: 13 Aug 1994 03:00:04 GMT
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!gatech!nntp.msstate.edu!olivea!koriel!newsworthy.West.Sun.COM!abyss.West.Sun.COM![e-mail]
Subject: RG58 versus Thin Ethernet
To: [e-mail]

In article [e-mail],  [e-mail] (Clay Jackson) writes:
>Alastair "J." Downs ([e-mail]) wrote:
>
><test figures that showed ENet a bit less lossy than RG-58 deleted.
>
>Interesting.  Well, it just so happens that I needed a run of
>net cable between two computers, and had some RG58 handy - so...
>
>Does anyone know of a source for 'real' (ie solder on) BNC connectors
>in the Seattle area?  All I can find are the funky 'crimp on' or
>'screw on' ones that aren't worth a damn.

Well, the screw-on BNC connectors have always sucked for me, but the
hex crimp connectors, properly applied, kick butt on all the others.
Save up the $25 or so to get a crimping tool, and you'll never go back...

---
 * Dana H. Myers KK6JQ, DoD#: j    | Views expressed here are    *
 * [phone]         | mine and do not necessarily    *
 * [e-mail]    | reflect those of my employer    *
 * "Sir, over there.... is that a man?"                         *

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

Date: 14 Aug 1994 06:22:27 GMT
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!gatech!asuvax!chnews!scorpion.ch.intel.com![e-mail]
Subject: Should feedline lenght change the VSWR?
To: [e-mail]

In article <32jngh$[e-mail]>, Micron3 <[e-mail]> wrote:
>
>   I am curious why the fact that the RF Analyst has a
>microprocessor in it would affect the accuracy?

Hi again, Terry. There are millions of digital bits roaming around
inside a microcomputer. RF fields can change those bits. Somewhere
inside the device they probably do an analog to digital conversion
and a one bit error can be a 50 percent error. I would not trust any
readings done with ordinary ham-grade test equipment in the presence
of the antenna near field and especially not anything containing a
microcomputer. Away from EM fields, it should operate just fine.

>What I was
>trying to understand is the fact that I read a VSWR at the antenna
>on 14.200 MHz of 4.3 - 1 and in the shack it reads 1.5 while on
>21.200 I read 2,1 - 1 at the antenna and 2.4 - 1 in the shack?

It's likely that the characteristic impedence at the antenna is not 50
ohms and remember your SWR meter is standardized for 50 ohms. If
the characteristic impedence at the point of measurement is not the
same as your SWR meter, results may look wierd. For instance, in my
earlier example of a 50 ohm antenna fed with one electrical wavelength
of 450 ohm transmission line and an SWR of 9/1, a 50 ohm SWR meter at
the generator will not read 9/1. You would need a 450 ohm SWR meter.

>The gentleman at the store told me this is normal and I need to cut
>the coax feed to 65 feet and then the VSWR curves would fall in
>place as the VSWR varies up and down with length. Cheers, Terry  KJ7F

Maybe you could work this thing backwards. By measuring the SWR and
impdeance at the generator end and knowing the length and matched-line
loss of the transmission line, you can calculate the SWR and the
impedance at the antenna. The adjustments on these multi-band verticals
interact so that changing the SWR on one band will also change the SWR
on the other bands. I would be tempted to feed it with ladder-line and
an antenna tuner and forget the SWR.

73 and good luck, Cecil, KG7BK, OOTC  (Not speaking for Intel)

--
 Intel, Corp.
 5000 W. Chandler Blvd.
 Chandler, AZ  85226

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

Date: 12 Aug 1994 22:15:34 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!csulb.edu!nic-nac.CSU.net!usc!elroy.jpl.nasa.gov!news.aero.org!sparky1.aero.org![e-mail]
Subject: tunor humor
To: [e-mail]

In article <32gk09$[e-mail]>, [e-mail] writes:
|> Where the heck can I mount a -8 ft long antenna?... and how long is

Just the ticket for those condo dwellers and towns with antenna
restrictions! Put it up as high as you can, use a sky hook even!

:-)
Yours,
cantrell, WA2VXU

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End of Ham-Ant Digest V94 #261
******************************