Schematics

This page has information on my shack projects. See the left side of the page for other operating modes and projects.
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Note: Some schematics are shown on different pages from this website.

Motorola Radius Maxtrac GM300 Programmer

Kenwood KPG-4 Compatible Programmer

Icom CI-v interface

EF Johnson 8615/8640/8655 interface

My MAX232 interface box

Yaesu VX5r programming interface

Two Transistor Level Converter

Homebrew Echolink Interface

PLRI circuits

Motorola Radius Maxtrac SM50 SM120 M120 M216 GM300 Programmer.
This programmer will work on just about every Motorola mobile radio.

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Kenwood TK760/TK762/TK860/TK862 Programmer
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Icom CI-v interface
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EF Johnson 8615/8640/8655 programmer
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My MAX232 Interface box
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I built this MAX232 interface box several years ago, and it has been very useful to have in my shack. This unit acts as a RS232 to TTL/CMOS level converter. Many devices capable of serial data communication do not use RS232 levels (-12v / +12v) but instead use TTL/CMOS levels (0v / +5v).

While cables are available for purchase from the radio manufacturers or aftermarket, I'd much rather be able to make my own cables.

Instead of building a new MAX232 circuit for each type of radio I wanted to interface, I built one interface, and would build a simple cable from the interface to each radio.

The interface features a 3 terminal (stereo) 1/8" (3.5mm) jack for TxD, RxD and Ground. The 1/8" jack is wired as such:

Tip = RxD (Max232 pin 9)
Middle = TxD (Max232 pin 10)
Ring = Ground

I chose this pinout so that a simple 1/8" (3.5mm) mono/stereo adapter could be used for Icom CI-v. This combines RxD and TxD on the tip of the mono plug, and ground on the ring of the plug. A simple 1/8" mono plug can then be used from the interface to the radio(s).

I also decided to power my unit independent of the PC and radio. I included a 5 volt regulator on the PCB and installed a power connector on my project box. This will allow operation with all PCs and radios. A 9 volt wall wart from a discarded cordless telephone powers the unit. For mobile/portable use, a simple 9-volt battery would suffice, or I could use vehicle power instead.

For the EF Johnson radio programming cable, I used a standard CAT5 cable with RJ45 connector on one end, and a 1/8" (3.5mm) stereo connector on the other end. The RJ45 connector must be ground down to fit the socket on the EF Johnson radios. I start with a bench grinder and finish with a file.

VX5r Programming interface
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This is another level converter circuit using the MAX232.
I had to experiment a little, but found that all it took was one extra diode to use my MAX232 level converter to program the Yaesu VX5r.

I recommend adding the diode external to the level converter if you plan to use your converter for other tasks, such as Icom CI-v. I was able to include the diode inside the shell of the 1/8" (3.5mm) connector.

Two Transistor Level Converter
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This one's even easier to construct! I built and used this level converter first because the MAX232 is not readily available in my area.

This circuit should work in place of the MAX232 for most/all of the above circuits.

Use any NPN transistor. See above for wiring details for Icom CI-v. I've heard some reports that Icom radios may not communicate over 9600 baud with this interface. Try setting the baud speed on your Icom to 9600 if it doesn't work at first. Believe me, 9600 is plenty fast for CI-v!