All of these radio programming cables use a level converter circuit, RS232 to/from TTL. The level converter can be as simple as two transistors, or to be fully RS232 compliant, a Maxim MAX232 chip. In fact, a MAX232 has two such circuits on a single chip!

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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Click on a link below to jump directly to a schematic.
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

Alinco DJ-G29t programmer ERW-7 ERW-4C compatible

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

LVB Tracker / Kansas City Tracker interface

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

Click on picture to enlarge image.

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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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efj_max232.jpg - 59377 bytes

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.

Alinco DJ-G29t programmer ERW-7 ERW-4C compatible
Click on picture to enlarge image.
djg29t_max232.jpg - 85282 bytes

After purchasing my Alinco DJ-G29t, I was amazed to find out that Alinco expects you to buy not one, but TWO cables in order to program the radio! Combined, the cables cost nearly $100!

You can build your own ERW-7 ERW-4C compatible cable for next to nothing with items you probably have laying around. If you do not have access to a MAX232 chip, use the two NPN transistor plan (also on this page). Besides the level converter, a steering diode is used, so that TxD and RxD can occupy the same pin.

Electrically, this cable is the same as the Yaesu VX5r, but a standard 4 pin 3.5mm connector does not fully insert into the Alinco.

I solved this problem by using the 4 terminal plug from an old set of Ipod earbuds. Lightly burn off the enamel coating from the wires before soldering.

Also, note that you will have to remove the heat shrink from the Ipod cord and insert the plug quite far into the radio to reach the contacts (due to the recessed design of the speaker/mic jack).

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
Click on picture to enlarge image.

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.

706_amp_keying.jpg - 37534 bytes

VX5r Programming interface
Click on picture to enlarge image.

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.

vx5r_max232.jpg - 37874 bytes

LVB Tracker / Kansas City Tracker interface kct.jpg - 102736 bytes

I built this interface originally for my Kansas City Tracker board. I have since added a LVB Tracker box to my station. This interface takes much of the load off the tracker box, and also adds 4 directional LEDs in a diamond pattern, so it is easy to see when the computer is steering the antennas.

Two Transistor Level Converter
Click on picture to enlarge image.

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!

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Last Updated October 11, 2014
©1997-2014 Kyle Yoksh