CB radio question

[68ROX]

SWR = Standing Wave Ratio

How much of your RF transmitted power goes OUT the antenna, and how much comes BACK...

HIGH SWR means very bad antenna efficiency, and possible final damage.

LOW SWR means better antenna efficiency, and getting the most from the power you transmit.

Antenna tuners (for as low as $50 and as high as $800) can be used between the transmitter and antenna to make the SWR be 1 to 1.

You can load up a set of bedsprings with an antenna tuner and make contacts.  I've loaded up a lawn chair and made contacts on 28 mHz.


The cheapest base antenna you can make is a half wave dipole, fed with RG/8 coax for about 15 bucks.  Get it up 60 feet, and you will make AM contacts with 5 watts out to about 50 miles on ground-wave.  On SSB (12 watts) out to about 100 miles on ground wave.


68ROX
K5TEN

[eskimo2]

Originally posted by AquaShrimp
Seeing as how I've used CB radios for years, and I'm also a licensed ham radio operator (KE4TMG), let me give you this advice.  The antenna is the most important part.  With cb radio, the larger the antenna, the better.  It will increase your broadcast radius, other stations will hear you better, and you will hear them better.

Can you run a wire up a tree, or does shape and thickness matter?

[68ROX]

Originally posted by eskimo2
Can you run a wire up a tree, or does shape and thickness matter?

You could, technically, that would be an end fed vertical...not a very effecient antenna.

Antennas can be constructed with anything from speaker wire (I'd advise against it) all the way up to 3" and 4" aluminum tubing.

If you wanted a cheap, efficient, base station antenna, I'd do with the half-wave dipole.

See Example & How Long it Needs To Be HERE

If you wanted to mainly talk with other base stations....use the "flat top" dipole configuration for horizonal polarization.  If you wanted to talk base- to- mobiles...simply use the "inverted Vee" or slope the ends down at 45 degree angles for vertical polarization (used by mobile CB stations).

For 27.000 mHz, the antenna is overall 17.3 feet, or a little over 8 1/2" feet long on each side.  Dipole center insulators cost about 6 bucks and are easy to solder the wire to...then screw the coax into the bottom, raise the center and ends into a tree using fishing line and a slingshot, and your are in business.

If you get it up to 60', it will exhibit some gain (not much) of 2 to 3 dB (meaning your 5 legal watts now sound like 10 to 15) without using illegal amps.

If you REALLY want some LEGAL base station gain....go with a beam antenna!

For gain on a mobile station, your talking about having to co-phase 2 identical antennas (you see this on truckers a lot).  The best mobile single antenna is the 102" whip, grounded to the car body.

Good Luck!



68ROX
K5TEN (3 QSLs short of confirmed 100 countries!)

[ariansworld]

question, I was testing my radio today,  is there supposed to be static all the time?  and do I want the meter thing on my radio to have 1 bar or more bars?   I am using an antenna that i bought from radioshack that has a magnetic base.

[HB555]

There is a knob called "squelch".
Turn it probably clockwise until the static just goes away.
You will still hear anyone in the area with a strong enough signal to come in over the squelch. If you are trying to talk to someone far away, you may not hear them. Just go down on the squelch until you are through talking, then turn it back up to where the static just stops.
Static gets old pretty quick.
While mobile, you may need to turn it up a bit more due to alternator whine, tire static, etc.

[rpm]

CB's are AM radios. You will almost always have white noise.

[Excel1]

Originally posted by rpm
Grids, plates, filaments. Ah, the good 'ol days when you could cook dinner over the tubes while DXing.

yup, and where the volts can jolt, and 600 of them really hurt. once i was fiddling around in the finals comparment of a yaesu ft-101 with the tubes juiced-up, got careless, and got belted. never made that mistake twice

[68ROX]

Originally posted by Excel1
yup, and where the volts can jolt, and 600 of them really hurt. once i was fiddling around in the finals comparment of a yaesu ft-101 with the tubes juiced-up, got careless, and got belted. never made that mistake twice

That's a great 70's era rig...wish I had one!

Station here is:

Yaeseu 757 GX/Mk II
Kenwood Twins (T599/R599D)
Kenwood TS-& 700A (2m All Mode)
Icom V8000 2m Mobile
80m Dipole @ 55'/MFJ Tuner
3 element 10m Beam @ 30'

CB- Cobra 2000 Base
10m Quad Loop @ 35'

I don't use the CB much, except to help coordinate local emergency traffic.  We get nasty ice storms from time to time, and it's usefull for that.  I can rig up a wire vertical in a heartbeat that is impervious to ice if need be.


68ROX
K5TEN