Two-way RF communication

Hi there,

I am interested in building a RF-communication project - i.e. like walkie-talkies. I live in South Africa - there are loads of two-way radio's available for purchase but I would like to build this myself as a hobby project.

In terms of range I am thinking of anything up to 1 km.

Can anyone point me in the right direction - kits, schematics?

Thanks

 

Hi Rob,

Thanks for your reply - the second link is broken - could you repost please?

An update to my question - I found the following site http://www.gw1tdv.co.cc/ which features a circuit:



This would be ideal for what I plan to do - the only thing I am unclear about is the component labelled "X1" - is this a crystal and how would I know what frequency?

The text with the circuit states that the two units operate on 49.860MHz for one unit and 49.410MHz for the other. Is this the frequency of the crystal?

 

Thanks for the info.

Seeing as these units are meant to run in duplex more, am I correct in saying that the frequencies need to be different on the two units? So that means I get the one crystal in 49.860MHz and the other in 49.410MHz?

Pardon my ignorance, I am learning new things about this hobby every day

 

This is supposed to be a radio intercom that you can use on a motorcycle to communicate to your passenger. The site states: "As it is difficult to use a PTT on a motorbike a continuous transmission / reception duplex system was required."

So I guess it has to run in full duplex?

 

Not sure I understand - this diagram shows the mic on bottom left (close to the 330R resistor) and the loudspeaker on the right?

 

Ok, that makes sense when the loudspeaker is also the mic - but with this design, where the mic and loudspeaker is separate would I still need to reverse the current?

 

Hey Rob, thanks for all your assistance, you've really helped me out a lot