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.

Multi-radio serial / parallel port interface

Asterisk parallel port interface

Motorola Radius Maxtrac GM300 Programmer

Kenwood KPG-4 Compatible Programmer

Icom CI-v interface

EF Johnson 8615/8640/8655 interface

Twin MAX232 interface box

Icom 706 HF amplifier keying circuit

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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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.

Twin MAX232 Interface box
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I built this MAX232 interface box in 2012 to replace a single MAX232 box built in 2002. I wanted to try using Ham Radio Deluxe as my satellite tracking/tuning software, and it would not operate more than one radio per RS232 port! The Icom CI-v protocol allows for up to 4 radios to share a single interface, but Ham Radio Deluxe does not support this.

This unit acts as two RS232 to TTL/CMOS level converters. Many devices such as radios use serial data communication, but do not use RS232 levels (-12v / +12v). These devices instead use TTL/CMOS levels (0v / +5v).

This unit has two DB9 ports, and two 3.5mm jacks. Each circuit is identical, but completely separate. This box is essentially the same as two of the expensive Icom CT-17 boxes, although this can do even more!

Since level converters are widely used to program radios and interface equipment, I use mine for a variety of tasks in the shack. Instead of building a new MAX232 circuit for each type of radio I wanted to interface, I built one interface box, and would build a simple cable from the interface to each radio.

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

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

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

Circuit B: Tip = RxD (Max232 pin 12)
Middle = TxD (Max232 pin 11)
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.

Icom 706 HF amplifier keying circuit
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I built this circuit in 2013 to key my Ameritron HF amplifer. The typical twin-NPN circuit found on the Internet did not work for me, so I built this one instead.

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!