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Date:         Sun, 3 Dec 2000 10:48:40 -0800
Reply-To:     David Marshall <vanagon@VOLKSWAGEN.ORG>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Marshall <vanagon@VOLKSWAGEN.ORG>
Subject:      Re: CB/Ham Radio Antenna Mounting [and choice]
Comments: To: Steve Schwenk <steve@syncro.org>
In-Reply-To:  <3A2A8E25.CFCFE2BC@syncro.org>
Content-Type: text/plain; charset="us-ascii"

Here is a small lesson on radio power by VE7PBS!

CB radio (AM, 27MHz) is restricted to 4W. Most HAM radio HF (High Frequency or 500KHz to 30MHz) gear transmits at 25W in the AM band and 100W in the FM band. Antennas are rated at "so much" gain. For every 3dB of gain you are in effect doubling your transmitted power. Most of the CB radio that you are hearing from many thousands of miles away is a usually result of a few factor.

- Skip (signal bouncing off the atmosphere) - Really good antennas - Illegal power output through amps or using HAM gear in the HAM bands.

Now, getting an amp or using HAM gear is expensive and it is technically illegal - but I don't think anyone is going to arrest you for doing it... hence technically.

The thing to do is get the antenna with the most gain possible. For example a 1/4 wave length antenna has 0dB gain or when you transmit you are transmitting at an effective 4W. If you were to get a loaded coil for the bottom of the antenna it may give you something like a 3dB gain or 8W of effective transmitting power. You will be hard pressed to find anything better than 3dB gain mobile antenna at 27MHz. Now, let say you found that mystical 6dB gain antennas - the 4W radio would be transmitting at an effective output of 16W! As you can see the quality of the antenna is the important thing. One more word to the wise. Get the antenna professionally turned with a SWR meter... if it isn't turned correctly you can damage your radio and it will not be running a peak efficiency.

David Marshall

Fast Forward Autobahn Sport Tuning 4356 Quesnel Hixon Road Quesnel BC Canada V2J 6Z3 mailto:info@fastforward.ca http://www.fastforward.ca Phone: (250) 992 7775 FAX: (250) 992 1160

. Vanagon Accessories and Engine Conversions . Transporter, Unimog and Iltis Sales . European Lighting for most Audi and Volkswagen models

-----Original Message----- From: Steve Schwenk [mailto:steve@syncro.org] Sent: December 3, 2000 10:17 AM To: vanagon@volkswagen.org; vanagon@gerry.vanagon.com Subject: Re: CB/Ham Radio Antenna Mounting

It sounds like you are hitting the skip...most ok radios can transmit thousands of miles for a short time when conditions are just right, but are limited to 10 - 20 miles or less under ordinary conditions, depending on watts and antenna. I sure wish there was a mobile that would transmit like that every time! Maybe with a 500 watt amp! How many watts do radio stations use?

David Marshall wrote: > > The coil is made by Sinclabs - the whip... dunno - just a standard stainless > steel whip. > > David Marshall > > Fast Forward Autobahn Sport Tuning > 4356 Quesnel Hixon Road > Quesnel BC Canada V2J 6Z3 > mailto:info@fastforward.ca http://www.fastforward.ca > Phone: (250) 992 7775 FAX: (250) 992 1160 > > . Vanagon Accessories and Engine Conversions > . Transporter, Unimog and Iltis Sales > . European Lighting for most Audi and Volkswagen models > > -----Original Message----- > From: Steve Schwenk [mailto:steve@syncro.org] > Sent: November 30, 2000 8:36 AM > To: vanagon@volkswagen.org > Subject: Re: CB/Ham Radio Antenna Mounting > > David, what kind of antenna do you use? Sounfds great. > steve > > David Marshall wrote: > > > > In my Syncro Double Cab I mounted a 5/8 whip and coil for 11m and have > > talked a few thousand miles away on CB! Just with a $100 4W CB radio that > > you can get a Rat Shack.... > > > > David Marshall > > > > Fast Forward Autobahn Sport Tuning > > 4356 Quesnel Hixon Road > > Quesnel BC Canada V2J 6Z3 > > mailto:info@fastforward.ca http://www.fastforward.ca > > Phone: (250) 992 7775 FAX: (250) 992 1160 > > > > . Vanagon Accessories and Engine Conversions > > . Transporter, Unimog and Iltis Sales > > . European Lighting for most Audi and Volkswagen models > > > > -----Original Message----- > > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf > > Of Steve Schwenk > > Sent: November 29, 2000 5:08 PM > > To: vanagon@GERRY.VANAGON.COM > > Subject: CB/Ham Radio Antenna Mounting > > > > I have installed a radio in my syncro that transmits on > > 10, 11 (CB) and 12 meters. After much pondering and > > asking for advice, I installed the antenna on the roof > > over the passenger cab area. It is about 50" tall, > > with a thin whip that can be easily removed, and that > > is very flexible so it can whack into trees and such > > without getting destroyed. The antenna has an NMO > > mount. I drilled a 11/2" hole in the fiberglass and a > > 3/4" hole in the metal roof. I ran the coax through > > the right side pillar. It is a very clean > > installation, the antenna is not very visible it is so > > thin and I can still use the luggage rack no problem. > > I get 1:1 SWR at 27000 . > > > > Last week I took a trip into the desert. I tested the > > radio and managed to get someone on the other side of a > > 10,000 foot mountain range (I was at about 1400 feet) > > about 25 miles away. It was my only real test attempt, > > but the result was pretty good. At the time, I was > > about 2 hours from the nearest paved road and 21/2 > > hours from the nearest phone. Very reassuring! > > > > So, it appears that the roof mount provides a good > > ground plane and was a good choice. I will also be > > able to seal everything up like it was never there if i > > ever want to.


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