[HoustonHam] this is a very elementary question, but (Christopher Mitchell)

[Bill Buoy]

Hi, Chris

1 - Most mobile or base antennas RS sells for CB are 1/4 wave. It is indeed
possible to cut some off these to resonate them at 10 meters. Pick a
frequency you want to operate on or something near the center of the range
you want to operate on and plug that number into this formula:

234/F=length in feet.

This will work if it is truly a 1/4 wave with no loading coil. You can
determine if it is by measuring the length of the whip from the tip to the
setscrew that holds it in the base. If it is close to 102", it's an 11 meter
1/4 wave whip. If it is shorter, there should be a loading coil in the
magnetic base.

In that case, you can resort to the trial-and-error cut-to-fit method if you
have an swr meter or if the radio has one built-in. Shorten the whip, about
a half an inch at a time until the SWR starts to drop. Keep the
transmissions short to limit the stress on the finals. Once you get the SWR
under 2:1, leave well enough alone - mag mount installations seldom get
perfect SWR, because the ground plane is often less than ideal.

2 - The length isn't that critical for reception. If signals are there, you
should hear them just as you have it set up now. As someone else commented,
the band is pretty dead right now. Just be sure that the base of the antenna
is on a good ground plane - a car roof or trunk, a steel shed roof, etc.

If you are operating from home, consider stringing up a 10 meter dipole -
they are simple to make and tune. Even a simple one strung up inside will
work. At 10 watts, the radiation issues are minimal. There is plenty of good
design info on the web, and all the parts are as close as your friendly RS
store.

Congrats on the recent upgrade, and good luck on the commercial pilot
training. I've been trying to find the time to work on instruments, but
between work and finances, it has been tough going.

The NARS (www.w5nc.org) Monday evening rag chew net someone mentioned meets
at 8:00 local on 28144. I try to join in from time to time, but don't always
make it. Most of the guys live in Northwest Houston, so it may be a bit of a
stretch across town. Not impossible, though - one regular on the net lives a
little south of Conroe. You are more than welcome to drop in. Some of the
guys go to 80 or 40 for a little while after the net to talk to a former
club member who moved to Hondo. The frequency is usually announced near the
end of the 10m net.


73,

Bill Buoy
N5BIA

Web page http://www.geocities.com/buoy@sbcglobal.net/home.html
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Message: 1
Date: Fri, 11 Feb 2005 16:09:24 -0600
From: Christopher Mitchell <chrism at lumin.us>
Subject: [HoustonHam] this is a very elementary question, but
To: houstonham at mailman.qth.net
Message-ID: <8be55c6a446053051b301fbdce32ffd1 at lumin.us>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

Hi, folks,

I'm down in Pasadena with this old Radio Shack gear that a friend of
mine bought on a whim years ago.  He hasn't yet gotten his license, so
he wanted me to see if it worked.  Well, I have no experience with 10m
so I don't know what I should expect, if anything, but given that the
ground wave should work about as well as CB I am a little surprised
that I don't hear anything but static and a few harmonic tones across
the entire band in SSB/AM/FM.

<snip>