CB Walkie-Talkie

Submitted by fyl on 30 March, 2008 - 16:52.

Yeah, that only AM 11 meter kind. It appears that they are legal here based on the TELCOR site. It isn't clear whether you actually need to license them or not. But, I want to try a pair to see if they will do what I want.

In the Geek Ranch, I tried 450MHz walkie-talkies. As I expected, they are useless to talk from the lower parts to most of the higher part because, well, there is a hill in the way. That frequency doesn't handle bending.

I have been thinking about alternatives but they are expensive, complicated or both. But, I am thinking the old CB frequency might work. Bending will happen ok. The two main reasons they are pretty useless in populated parts of the U.S. are:

  • Impulse noise such as from automobile ignition systems
  • Just too many users in a small area

Well, where we are in the Tisey preserve, neither of this problems exist.

Anyone seen any of these units? Or, better yet, anyone have a pair I could beg, borrow or steal to test my idea out?

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I just happen to have two

Submitted by charliedawson on 30 March, 2008 - 21:53.

I just happen to have two hand held 40 channel units, but I don't think they can help you from here in Pennsylvania. Besides, I seem to recall that the range of any CB unit was intentionally limited, and you would be lucky to get 4 miles even on line-of-sight.

Radio Coverage

Submitted by fyl on 31 March, 2008 - 08:14.

Ok, here goes a radio class. In the VHF and higher frequencies, line-of-sight is the rule. There can be some signal bending or "ducting" between layers of the atmosphere but that's about it. As you get higher in frequency, bouncing the signal off of building (and even the moon) is possible. But, talking over a hill in a forest on, for example, 450MHz is something that just doesn't work.

On the other end of the spectrum is where what is called the ground wave is the most common way a signal gets to you. Take AM radio as an example, Stations tend to be located on flat land and you can hear the signals in places where you have no view of the transmitter.

In the range of frequencies in between, how the signal travels. The ground wave is still important up to maybe 30 MHz but bouncing off layers in the atmosphere is another consideration. This bouncing depends on the frequency, time of day and sun spots. And, no, you don't have to understand this to see why I think CB radios may solve my problem. But, I have a friend who talked to someone 500 miles away on a 1/10 watt CB walkie talkie and I have heard people in their car in Japan talking back and forth on a radio in my car in Olympia, Washington on the adjacent (10 meter) ham band.

This ground wave is what could make a CB radio work where a VHF or UHF one would not. I don't need a long distance—about 2 kilometers maximum but I do need the signal to "follow the terrain". That might work and is certainly worth a try before I decide to build a UHF repeater station to solve the problem.

The reasons CB tends to be pretty useless in the U.S. in most cases are:

  • Impulse noise (such as from car ignition systems) significantly interferes with reception.
  • In population centers, the 40 available channels are too full to be useful for much.
  • Skip (signals from far away during certain atmospheric conditions) can make a signal from 1000 miles away stronger than one from 2 miles away.

With the exception of the last item, this is just not going to be a problem in the Tisey reserve.