QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940199.txt

Internet Message Format | 1994-11-13 | 23KB

Date: Sat, 25 Jun 94 04:30:09 PDT
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #199
To: Ham-Ant


Ham-Ant Digest              Sat, 25 Jun 94       Volume 94 : Issue  199

Today's Topics:
                           Antenna Question
                            Coaxial Relays
                     Comet 2M/440/cellular mobile
                          Dipole impedance?
             Help identify Thick Ethernet cable (2 msgs)
                     HF Mobile Antennas (4 msgs)
                       Quadfiliar helix for GPS
   QUESTION: WANT TO BUY A CAR RADIOTRANCEIVER. WHAT IS A GOOD ONE?
       Thick Ethernet cable in place of RG cables ??? (2 msgs)

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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: 24 Jun 1994 08:17:54 GMT
From: agate!howland.reston.ans.net!vixen.cso.uiuc.edu!airwaves![e-mail]
Subject: Antenna Question
To: [e-mail]

I'm writing an article for my station here in Washington.  What I want to know
is if there is a "better" design for an antenna than the "Sterba Curtain"
antenna.  What I'm looking for is an antenna that can be built by the average
joe/jane that is tuned to a specific frequency that can be used to pick up
a station say, thirty or fourty miles away (we're only a 100 watt station,
soon to upgrade to a 500 watt transmitter).  From what I've read, the best
design is this "sterba curtain" design, with the base measurement of 62.5
inches (our frequency is 89.9 FM).  But this design may be a bit to large
for some people to build.

I'm also curious as to the effect of grounding.  That is, where placement of
an antenna is adversely affected by its enviorment (i.e. putting your antenna
on the outside of your aluminum-sided house!).  How could these effects be
canceled, and how far should an antenna be away from these "grounded" materials
before the signal will come in?  How far up should an antenna be from the
ground?  How far away from your reciever can the antenna be?

A lot of questions I realize.   But what the hell, I'm curious!  If anyone
could direct me towards a good book on the subject I'd like that too.

[e-mail]

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

Date: 24 Jun 94 15:55:45 GMT
From: [e-mail]
Subject: Coaxial Relays
To: [e-mail]

Subject: Coax Relays
From: Ron Klimas, WZ1V
To: [e-mail], [e-mail]
CC: [e-mail]

Tom WB7ASR wrote...

>>Can anyone tell me where I might find (purchase cheaply) some 12-24 VDC
>>relays that I can use to switch in/out my 2m and 70cm antenna preamps?
>>I need to take the premaps out-of-line before transmitting. They need to
>>operate at 145 and 443 MHz with minimum signal lost and capable of handling
>>150 watts of RF output power. I perfer PC mount type so I can mount them
>>inside the preamp bud box. Coaxial relays (Dowell or TohTus) are big and
>>require coax connectors.

I've been designing & using HB mast-mounted preamp systems for years.
Let me pass along some words of wisdom on relays. Beware of flea-market
bargain types unless you've memorized some Mfgr/part#'s/isolation/power
handling specs first.

1. Power handling capability: This is a manufacturers spec, but generally,
   relays w/ N connectors can handle more power than BNC types. BNC's are
   adequate for up to 200 watts at 432, however. Absolutely FORGET about
   PCB mount relays unless you design a PCB with 50 ohm input & output
   impedance etched lines to a preamp circuit on the same board! "Dead-bug"
   style mounting is for 25 watt or less systems and desperate souls.

2. Isolation: You need to ensure that no more than +10dbm (10 mw.) of power
   is applied to the preamp head input or output at any time. 200 watts of
   Tx power is +53dbm. The difference is 53-10 = 43db absolute minimum
   isolation required. Any good design should have a bit of overkill to
   avoid failure, and I would recommend at least 3 db worth in this case.
   What you really need then is a relay with 46 db of isolation.

Here are some I've measured in my lab w/ an IFR Spectrum analyzer:

                                                   ---- Db ISOLATION @ ----
            Relay type                             144MHz   432Mhz   903MHz
-------------------------------------------------  ------   ------   -------
Allied Control 607W coax leads only                  39       35       22

Amphenol 316-10082-3 BNC shorting type 26vdc         83       67       60

Danbury-Knudsen CR246BNS BNC 26vdc                   39       29       22

Dowkey 60-2801 Type N                                34       25       20

Dowkey 77-2202 BNC 12vdc                             43       33       23

Joslyn JDS315-10002-3 BNC 26vdc                      43       30       24

To Tsu CX540D BNC shorting type 12vdc                75       56       50
(also available in type N)

I use To Tsu CX520's with type N connectors for my 2 meter kilowatt station.
The 2m isolation on these is similar to the 540D. I run only 100 watts on
432 and use the Amphenols listed above. These can be bought at flea markets
for $10-15 and are an excellent bargain. The problem is you can't run 1000
watts through BNC connectors. The To Tsu's aren't cheap. $85 new last time
I checked. Well worth it for high power use, though.

Next problem is how to automatically control switching of the relays so
you can't accidentally transmit into your nice expensive hard to reach
preamp. What you'll need is a sequencer. There are commercial ones available.
(ARR, SSB Electronic, etc.). But if you want to homebrew one, I would
recommend you read my design article in March 1992 73 Magazine. The drilled
PCB's for this are still available from FAR Circuits for about $5.
There is a also a design in 1 of the Handbooks. I tested this one on a D.S.O.
and found that its' timing was flawed when using CW semibreak-in. (It would
engage the preamp before one transceiver of mine went back to receive mode).
This will blow out preamps consistently over time. Forget about this one
unless you are willing to give up your paddle !

I am now looking into MOV protection for preamp DC supply inputs. These
devices are fairly cheap for the amount of protection they provide against
Lightning E.M.P. pickup on your DC line. We hope to be putting in an article
on the selection and use of these from one of our guys in the Proceedings
of the 20th Eastern VHF/UHF Conference this August.

73 - Ron, WZ1V, FN31, email: [e-mail]
                      Engineering/Ham BBS: (203)-768-4758 14400,8,N,1 ANSI
                      Voice: (203)-589-0528 when I'm home.

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

Date: Fri, 24 Jun 1994 17:53:46
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!library.ucla.edu!europa.eng.gtefsd.com!news.umbc.edu!eff!news.kei.com!ssd.intel.com!chnews!ornews.intel.com!ccm.hf.intel.com!brett_miller@network.
Subject: Comet 2M/440/cellular mobile
To: [e-mail]

In article <[e-mail]> [e-mail] (Lance Lee) writes:

>In article <[e-mail]>, Robert Sadur
><[e-mail]> wrote:

>> I saw Comet has a combination ham and cellular antenna.  Does
>> anyone have experience with this?  And does anyone know where
>> I can get a triplexer for these bands or a duplexer that would
>> have 2M and 440 on one side, and cellular on the other?  It seems
>> strange that Comet doesn't sell such a thing but it seems they don't.
>> 73
>> Bob Sadur AA2NY

>Isn't cellular between 860-900 mhz?  I don't remember exactly...
>From an AES catalog the COMET part nos. which should work are:
>CF-413OA duplexer
>CFX-431A triplexer
>CFX-4310C triplexer
>The high side is supposed to handle from 840 to 1400 mhz

>DIAMOND has the following which should work too:
>MX-3000N (high end:  850-1300 mhz)
>MX-3000D
>MX-3000DN
>MX-2000 (high end:  300-950 mhz)

>There's also an MX-37N but the specs indicate that the high end is between
>900-1300 mhz, so you probably shouldn't get this one.  Good luck!

The cell phone transmit is 45 MHz below, so you need to include down to about
830 MHz.


Brett Miller N7OLQ                  [e-mail]
Intel Corp.
American Fork, UT

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

Date: 24 Jun 1994 09:33:21 GMT
From: elroy.jpl.nasa.gov!swrinde!pipex!lyra.csx.cam.ac.uk!warwick!news.shef.ac.uk!silver![e-mail]
Subject: Dipole impedance?
To: [e-mail]

I've built several home designed, low power (approx 0.5Watts) short wave
radio transmitters. At the moment I'm operating from a home made dipole
aerial mounted horizontaly with a full span of about 20 meters. To feed
the dipole I'm using 50 Ohm co-axial cable (not the best thing) but what
I'd really like to know is how do I adjust the dipole length to match the
impedances correctely. If anyone knows or has any equations relating
dipole length to impedance I'd be greatfull. Thanks

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

Date: Fri, 24 Jun 1994 13:55:02 GMT
From: ihnp4.ucsd.edu!usc!cs.utexas.edu!convex!news.duke.edu!godot.cc.duq.edu!newsfeed.pitt.edu!gvls1![e-mail]
Subject: Help identify Thick Ethernet cable
To: [e-mail]

I have a piece of thick ethernet cable marked :

 Control Cable Inc. Baltimore MD. P/N 52016 E57891 TYPE CL2 75 (deg) C
       111/2 AWG (UL)

Any idea what is is?  Looks about the size of RG-8 with a yellow jacket.
Is it suitable for RF?  VHF/UHF?

I has N connectors on each end so I can't see what the inside looks like
unless I cut one off -- which I would rather not do.

=================================================================
Pete Rossi - WA3NNA                  [e-mail]

Unisys Corporation - Government Systems Group
Valley Forge Engineering Center - Paoli, Pennsylvania
=================================================================

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

Date: 24 Jun 1994 15:27:22 GMT
From: agate!howland.reston.ans.net!europa.eng.gtefsd.com!uhog.mit.edu!news.kei.com!ssd.intel.com!chnews!scorpion.ch.intel.com![e-mail]
Subject: Help identify Thick Ethernet cable
To: [e-mail]

In article <[e-mail]>,
Pete Rossi <[e-mail]> wrote:
>I have a piece of thick ethernet cable marked :
>Any idea what is is?  Looks about the size of RG-8 with a yellow jacket.
>Is it suitable for RF?  VHF/UHF? Pete Rossi - WA3NNA

Our Ethernet coax has almost identical RF characteristics to RG-8F.
It is not UV protected.

73, KG7BK, OOTC, [e-mail]

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

Date: Fri, 24 Jun 1994 17:28:04 GMT
From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!europa.eng.gtefsd.com!uhog.mit.edu!news.mtholyoke.edu!world![e-mail]
Subject: HF Mobile Antennas
To: [e-mail]

In article <[e-mail]> [e-mail] (Patrick Tatro) writes:
>In article <2u97la$[e-mail]> [e-mail] (STEVE BJARNASON) writes:
>>From: [e-mail] (STEVE BJARNASON)
>>Subject: HF Mobile Antennas
>>Date: 22 Jun 1994 11:35:06 GMT
>
>>I have recently purchased a Kenwood TS-50S for use as my HF rig.  I will
>>be using it mainly in my apartment but would also like to put it in my
>>4Runner to do some HF mobiling.  Problem is, I have never used an HF rig
>>mobile and am unfamiliar with the current crop of HF mobile antennas.  I
>>would appreciate any info that you might have or experiences (good or
>>bad) with specific antennas.
>>Please EMAIL me directly (see address below) or send a packet message to
>>me at VA3GE@VE3KYT.#EON.ON.CAN.NA
>
>>        '73 de Stephen, VA3GE
>>___________________________________________________________
>
>I'm doing the same. Hustler offered a triband setup I thought looked good.
>But as I look closer the bandwidth stinks. I dont know if thats the case with
>all mobile HF antennas but beware you may get reasonable SWR's on only
>a small portion of the band.
>

I've just gotten a TS-50S and put it in my Pathfinder. I have a 3/8x24
mount firmly attached to Thule roofracks, with 3/4 inch braid attached to the
mount, and connected to the body of the vehicle (the handles over the
rear doors, when removed, show bare metal, put the braid in under there,
and I get a great attachment on both sides of the truck).

For antennas, I was going to use my hustler stuff, but have never been
very happy with them. So, I got a WD4BUM hamstick for 75 meters (with
a base matching coil added), with reasonable results. For 40 meters and
above, I got a Carolina Bug Katcher from Lakeview (same outfit that
makes the hamsticks). I've used it for 40, 20 and 17. I have the antennas
on quick disconnects so that I can get the bug catcher down and change
the clips easily, or switch to the 75 meter stick.

Last night on my way home from work, I talked to an OK3 and an RA3 station.
Both gave me 57 reports (they got 59s, and were running 1000 watts). Both
were impressed with the decent mobile signal. I was running the TS50 at
50 watts. Later on, while waiting for a sked, I worked a 4 lander and
had s9 signals both ways on 20 meters with excellent quality.

Bandwidth on 20 meters is the whole phone band (and probably the upper part
of the RTTY/DIGITAL band within 2:1 SWR. 40 meters I get much less bandwidth,
but don't remember the figures.

73,

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

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

Date: Fri, 24 Jun 1994 18:44:48 GMT
From: ihnp4.ucsd.edu!swrinde!howland.reston.ans.net!europa.eng.gtefsd.com!library.ucla.edu!csulb.edu!csus.edu!netcom.com!netcom11![e-mail]
Subject: HF Mobile Antennas
To: [e-mail]

Check out the DK3 from High Sierra Antennas, Box 2389 Nevada City CA
95959, 916-273-3415
It's should work pretty well and is all-band.
Let me know how it works.
73, doug

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

Date: Wed, 22 Jun 1994 15:11:08 GMT
From: agate!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!server!stortek.com![e-mail]
Subject: HF Mobile Antennas
To: [e-mail]

In article <2u97la$[e-mail]> [e-mail] (STEVE BJARNASON) writes:
>From: [e-mail] (STEVE BJARNASON)
>Subject: HF Mobile Antennas
>Date: 22 Jun 1994 11:35:06 GMT

>I have recently purchased a Kenwood TS-50S for use as my HF rig.  I will
>be using it mainly in my apartment but would also like to put it in my
>4Runner to do some HF mobiling.  Problem is, I have never used an HF rig
>mobile and am unfamiliar with the current crop of HF mobile antennas.  I
>would appreciate any info that you might have or experiences (good or
>bad) with specific antennas.
>Please EMAIL me directly (see address below) or send a packet message to
>me at VA3GE@VE3KYT.#EON.ON.CAN.NA

>        '73 de Stephen, VA3GE
>___________________________________________________________

I'm doing the same. Hustler offered a triband setup I thought looked good.
But as I look closer the bandwidth stinks. I dont know if thats the case with
all mobile HF antennas but beware you may get reasonable SWR's on only
a small portion of the band.

73's
Pat N0WCG

>STEPHEN BJARNASON
>AIR QUALITY - HEALTH EFFECTS RESEARCH SECTION
>RM. 337, BLDG. 8
>TUNNEY'S PASTURE
>OTTAWA, ON  K1A0L2

>INTERNET: [e-mail]
>____________________________________________________________

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

Date: 24 Jun 94 15:11:47 GMT
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!howland.reston.ans.net!vixen.cso.uiuc.edu!aries![e-mail]
Subject: HF Mobile Antennas
To: [e-mail]

[e-mail] (Patrick Tatro) writes:

>In article <2u97la$[e-mail]> [e-mail] (STEVE BJARNASON) writes:
>>From: [e-mail] (STEVE BJARNASON)
>>Subject: HF Mobile Antennas
>>Date: 22 Jun 1994 11:35:06 GMT

>>I have recently purchased a Kenwood TS-50S for use as my HF rig.  I will
>>be using it mainly in my apartment but would also like to put it in my
>>4Runner to do some HF mobiling.  Problem is, I have never used an HF rig
>>mobile and am unfamiliar with the current crop of HF mobile antennas.  I
>>would appreciate any info that you might have or experiences (good or
>>bad) with specific antennas.
>>Please EMAIL me directly (see address below) or send a packet message to
>>me at VA3GE@VE3KYT.#EON.ON.CAN.NA

>>        '73 de Stephen, VA3GE
>>___________________________________________________________

>I'm doing the same. Hustler offered a triband setup I thought looked good.
>But as I look closer the bandwidth stinks. I dont know if thats the case with
>all mobile HF antennas but beware you may get reasonable SWR's on only
>a small portion of the band.

>73's
>Pat N0WCG

Well.....in general, the narrower the bandwidth, the better the efficiency.
So I wouldn't use the word "stinks". If you want to move up and down the
band you either have to get out of the car and readjust the stinger, or
set the antenna up say for lower frequency and use a remotely driven
series capacitor at the feedpoint to move up the band. How about that new
screwdriver motorized mobil antenna that was reviewed in CQ last month or
the one before? That's another way to do it....change the coil length
remotely to tune the antenna AND change bands.

Chuck Hawley.....KE9UW.....Urbana, Illinois
[e-mail]
School of Chemical Sciences, Electronic Services
University of Illinois, Urbana-Champaign

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

Date: Fri, 24 Jun 1994 15:22:40 GMT
From: elroy.jpl.nasa.gov!swrinde!cs.utexas.edu!wotan.compaq.com!twisto.eng.hou.compaq.com!pokey.eng.hou.compaq.com![e-mail]
Subject: Quadfiliar helix for GPS
To: [e-mail]

Just got onto this forum, so please excuse if this is a repeat question.
Has anybody tried to build an external antenna for a GPS?  In one of these
radio posts, someone mentioned that the quadrafiliar helix antenna was
what I needed and that the description could be found in old ARRL Antenna
Handbooks.  Well, I got the book, but the information is too general for
a novice like me to translate into an actual antenna.  Has anyone tried it?
Any suggestions?  ALthough I paid a lot for  the GPS, I hate to have to spend
the extra couple of hundred they want jst for 20' of coax and this antenna!
Thanks.

Susan Scott
email [e-mail]

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

Date: Wed, 22 Jun 1994 15:05:27 GMT
From: agate!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!server!stortek.com![e-mail]
Subject: QUESTION: WANT TO BUY A CAR RADIOTRANCEIVER. WHAT IS A GOOD ONE?
To: [e-mail]

In article <[e-mail]> TV "Ostankino" <[e-mail]> writes:
>From: TV "Ostankino" <[e-mail]>
>Subject: QUESTION: WANT TO BUY A CAR RADIOTRANCEIVER. WHAT IS A GOOD ONE?
>Date: Wed, 22 Jun 94 11:13:11 +0400
ANSWER:
ELECTRIC IN THE RF SPECTRUM

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

Date: 24 Jun 1994 09:21:31 GMT
From: lll-winken.llnl.gov!sol.ctr.columbia.edu!howland.reston.ans.net!EU.net!news.forth.gr!helios.intranet.gr!phaethon![e-mail]
Subject: Thick Ethernet cable in place of RG cables ???
To: [e-mail]

CQ Netters...

Has anyone ever used Thick Ethernet cables instead of the typical
RG 213, RG 214, H-100 cables ?? How does it compare with the RG cables ??

73's

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

Date: Fri, 24 Jun 1994 14:04:21 GMT
From: yuma![e-mail]
Subject: Thick Ethernet cable in place of RG cables ???
To: [e-mail]

In article <2ue8ir$[e-mail]> [e-mail] (Demetre Koumanakos) writes:
>Has anyone ever used Thick Ethernet cables instead of the typical
>RG 213, RG 214, H-100 cables ?? How does it compare with the RG cables ??

The college club I'm with got a big, wooden spool of yellow Enet cable.  We
called the manufacturer and they said it would work fine up to about 500 MHz.
It has a solid center conductor, two foil shields with two braided shields.
It was tough to get a PL-259 on it, but it works quite well.

Oh yeah, it's 50 ohm ;-)
Galen, KF0YJ

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

Date: 24 Jun 1994 15:18:54 GMT
From: agate!howland.reston.ans.net!europa.eng.gtefsd.com!newsxfer.itd.umich.edu!zip.eecs.umich.edu!yeshua.marcam.com!news.kei.com!ssd.intel.com!chnews!scorpion.ch.intel.com![e-mail]
To: [e-mail]

References <2u97la$[e-mail]>, <D>, <[e-mail]>.
Subject : Re: HF Mobile Antennas

In article <[e-mail]>,
Patrick Tatro <[e-mail]> wrote:
>
>... Hustler offered a triband setup I thought looked good.
>But as I look closer the bandwidth stinks. I dont know if thats the case with
>all mobile HF antennas but beware you may get reasonable SWR's on only
>a small portion of the band. 73's Pat N0WCG
>
Hi Pat, get a mobile antenna tuner and quit worrying about bandwidth.
You have a certain matched-line loss in the coax when the SWR is 1/1 and
it is usually neglible in an HF mobile installation. An SWR of 4/1 to 5/1
makes your transmitter unhappy but it only doubles the loss in the coax
which is still probably neglible. An antenna tuner makes your transmitter
happy, your coax loss is neglible, and your bandwidth increases as far
as your transmitter is concerned. A ten foot run of 9913 can tolerate an
SWR of 10/1 and still lose less than half a dB on any HF frequency. And
the lower the bandwidth of a mobile antenna, the higher the Q of the loading
coil, and the more efficient it is at radiating RF.

73, KG7BK, OOTC, [e-mail]

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

End of Ham-Ant Digest V94 #199
******************************