Date: Fri, 12 May 95 11:16:36 EDT
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: sas@opus.xyplex.com (Scott Sminkey - Sustaining Eng Group)
Subject: Re: CB Antennas and stuff (LONG!)
Hi everybody,
I've been catching up with the list traffic and saw the discussion on
CB antennas. Joel asked if any hams wanna comment. Sure, I'll comment!
(I've been a ham for many years now and was a CB-er before that...)
-- First, the topic of "unconventional" antennas...
Barry <BSNICHOLS@ulkyvm.louisville.edu> wrote:
>What I wanted to do was put full length antenna (maybe 2?) up
>under the long edge of my poptop. This would leave them horizontal and I'm
>not sure what problem that would be.
Brian Wolfgram <MWOLFMAN@aol.com> wrote:
> In reply to your concern over antennae hanging all over your bus, I know
>of a co. that may be of some help. Dakota Digital out
>of Sioux Falls, SD makes a really nifty under-dash antenna that is reportedly
>much superior to ext. antennae, and way tidier to install.
Ric <RGOLEN@umassd.edu> wrote:
>So I am about to replace it, and I'm wondering if anyone out there
>has had any experience with those "black boxes" that are supposed
>to allow the radio antenna to be used as a CB antenna? Or am I
>doomed to drilling some holes?
All of these antenna ideas will work to some degree, but I guess the real
question is how well they will work. The best antenna for CB or ham or any
other kind of transmitting is one that is "full sized". By this I mean one
that is not shortened by loading coils, top hats, etc. For CB this means a
length of about 102 inches. A magmount antenna doesn't work as well as a
type with direct contact to metal. A thru-glass antenna works even worse.
The antenna inside the poptop idea that Barry has, I'm sorry to say, will
most likely work much worse that what he has. The problem is that it is
simply so close to the metal body that its radiation pattern will be terrible.
Being horizontal ("horizontally polarized") will also cost a lot in signal
strength (20dB for the techies out there). It will also require an antenna
tuner to get it to match properly to a CB and the know-how to adjust it.
The Dakota Digital under-dash thingy sounds like marketing smoke and mirrors
to me. It will be too small and too close to metal. The adapter box to use
your AM/FM antenna for CB is probably the best of these three unconventional
ideas, but the range will pale in comparison to a good CB antenna.
So what's a good antenna? The folks over on rec.radio.cb seem to agree that
the Wilson 1000 and K-40 are both very good. Again, the 102 inch whip is
still better than either of these. It is proof of a radio axiom I have heard
several times: "There's no substitute for metal in the air." to which I would
add "more metal is better than less metal." :-)
I have my low-frequency ham mobile antenna mounted to the side fender below
the air scoop on my '91 Camper. Of course it's a permanent (drilled) mount,
which I did when the Camper was less than one week old! My VHF ham antenna
is also a drill mount in the center of the luggage rack. You could drill a
large hole in the luggage rack and just stick a magmount to the metal roof.
I know that the metal areas on a Camper are limited, so I thought I'd share
my ideas. I've never understood why people have such an aversion to drilling
holes. A proper installation with a drilled hole will not rust, and I have
never ever ever heard of a single case of the value of a car going down
because of a clean, drilled-hole antenna installation.
-- On the topic of power, improved signal and range, etc.
Barry also wrote:
>I...need some more power. Is there a booster I can add?
and Joel Walker <JWALKER@ua1vm.ua.edu> wrote:
>as i understand it, the only thing you can LEGALLY do is to take the radio
>to a radio-repair person and have him/her tweek the set to obtain the
>maximum legal output. otherwise you can get an illegal linear amplifier and
>put in the line from the set to the antenna.
Joel is right on the money here. Linear amps on CB are illegal to own and
illegal to manufacture and sell. There cannot be any FCC "type-acceptance"
(which means the design meets technical approval) so the CB linears sold are
pieces of junk that *will* cause interference to everything under the sun
including other radio services like police, fire, etc. I have seen the
insides of CB linears and it is a sorry sight indeed to someone who has
also seen the insides of good radios and built quite a few, too. Don't waste
your money on a linear. Also, "tweaking" of a CB can only be done by
technicians with a proper FCC license. There's a reason for this: if a radio
is improperly adjusted, it can cause interference to other radio services.
This includes tweaking for more power and even messing around with the
modulation circuits (overmodulation causes splatter causes interference).
A new CB radio out of the box will be close enough to the maximum legal
power of 4 watts that it isn't worth your money to pay a technician to peak
it from perhaps 3.5 watts to 4 watts. It will make *no* difference.
Joe Clark <jclark@nexus.polaris.net> wrote:
>If you can still find them, power mikes are a good way to go. They don't
>boost xmit power, just assure 100% modulation -- filling up the pipeline,
>as it were. And they're legal -- or were last time I checked, which was
>about '76 at Laffin-idjit Radio (sigh).
Yes, power mikes are legal but they're a waste of money. CBs are required
to have circuitry to prevent overmodulation (too much audio on the signal).
If the audio level is too high, the audio is "clipped" and it sounds very
distorted and is hard to understand. A power mike can easily put too much
audio out and make for a really awful sounding signal.
Joel also commented about linears and said...
>but all that does is make you much louder much farther away. i'm not sure
>what it does for your reception.
Absolutely correct, Joel! Are you sure you're not a ham radio op, Joel? :-)
If you want to improve reception, get a better antenna and that will also
improve your transmitting range.
Finally, Joel said...
>those linear amplifiers are also illegal as hell. :) even though lots of
>turckers use them, and the FCC seems to have just given up on cb radio, it's
>still illegal.
You're right again, Joel. The FCC rarely takes action against a CB-er with a
linear *unless he interferes with another radio service* and then they're on
him like a ton of bricks. Congress authorized the FCC to impose much larger
fines in the past year or so. Every month I read in my ham mags about big
fines ($5000, $10,000, etc.) for people who violate the rules.
I hope this has been helpful. Feel free to send me direct email if you have
any specific questions.
As we say in ham radio, "73" (which means "best regards")...
- Scott ham: WO1G CB: KKA-2127
========
Scott Sminkey email: sasminkey@eng.xyplex.com
Sustaining and Specials Engineering voice: 508 952-4792
Xyplex, Inc. fax: 508 952-4887
295 Foster St. (Opinions, comments, etc. are mine,
Littleton, MA 01460 not Xyplex's...)
