Initial version and ideas

So I had the concept for this project. It had a goal, it had a way of achieving that goal, all that was needed was everything to get to that goal......so the planning begins

Amateur repeaters are really cool. Basically I have been using them for some 30 years. The concept is simple. A repeater does what the name implies, it repeats. Basically its two radios, one receiving on a fixed frequency, the other transmitting on another fixed frequency. When the receiver receives a signal, it tells the transmitter to turn on thus taking a signal on one frequency, and repeating it on another frequency. Repeaters can be in band ( working on 2 different frequencies in the same band) they can be cross band ( listening on one frequency in one band, and transmitting that audio on another frequency in a completely different band) they can be connected to a remote base radio, they can do lots of fun things.

I am building an in band repeater, with plans to attach a remote base. All of this needs to be figured in the design considerations. WAY easier to design with expansion in mind, than to try and add on later. For a few extra bucks in parts and pcb board area, its just easier to consider it now than to add it later.

The first design was with expansion in mind and built off the circuit designed by Kyle Yoksh, K0KN. His design was to use the parallel port on the node computer as the interface. I liked this idea for several reasons. One, if anything were to happen to the port, you can always add a new port and tell the computer to use the new one, so, if it blows up, its not a lost cause. Second his design was simple and easy to understand and use. Im not totally against using other folks designs, but I like to use their concepts and build my own ( the basis of open source hardware, anyway, right?) So I looked at what he had come up with and decided to embellish, but I give credit where its due, hence Kyles mention here!

This was the first adaptation for the controller. I decided to make everything modular, so I could plug in and take out what I wanted. The is one of the earlier examples of the radio module. Except for the addition of the 74LS00N, for inverting signals for later use, this is Kyles basic COR and PTT circuit. I did add a really simple power supply, and a connector. I tested this and it worked well on the parallel port. I used this design then as a basic building block.

The other part of this is what I call the " Main Board". This board I am going to use to route signals between the various modules. The early version of this also worked well, in the initial test.

This is version 2 of the main board. Basically the radio modules plug into the respective connectors marked for each radio ( RPT, CNTRL, AUX2 and AUX3) each port than control its respective radio or in the case of the RPT module, it received COR signals is sent that to the node computer, which in turn sends out a PTT signal to the repeater transmitter and keys it. While this design also worked, I discovered a flaw. One of the design points was if the node computer went off line, then the controller would keep the repeater going. In this design, somehow I got lost, and that feature wasnt added, but again these were early designs, and by no means a finished product......so off to revision 3....