Rich builds a simple GX12 key/paddle adapter for the Discovery TX-500

Many thanks to Rich (KQ9L) who shares the following tutorial describing how to build a compact key/paddle GX12 connector for the lab599 Discovery TX-500:

This adapter is simple, compact, and eliminated the need for yet another wire extension.

How to build a Discovery TX-500 key adapter

I love my Lab599 Discovery TX-500 however I was frustrated with all the extra “wires” hanging from the connectors on the rig.

I took inspiration from Vlad Solovey (RA9QAT) who posted his design for a small and compact 3.5mm jack that allows you to connect your paddles directly into a GX12 connector.

The build is very simple and requires only two components which I sourced from Amazon (item list has clickable hyperlinks) and some basic tools:

  1. GX12 5 pin connector
  2. 3.5mm stereo jack

Step 1: Cut the GX12 connector at the shoulder, I used an abrasive wheel on my rotary tool. A hacksaw will work fine as well.

Step 2: Enlarge the exit with a drill bit. You will need to unscrew the black connector holding the pins from the body of the connector. Choose a size of drill that will be only slightly larger than the body of your jack so it doesn’t wobble.

Step 3: Remove extra pins from GX12 connector. This can be easily accomplished by bending the tabs back and forth then pushing the socket out of the connector. You will need only three pins remaining, see diagram. You need pins 1, 2 and 5. Luckily these correspond exactly to the pin out on the 3.5mm jack!

Step 4: Trim leads on 3.5mm jack. I trimmed the ground tab to be the same size as the ring and sleeve tab. Test fit the jack to the GX12 connector, you may need to bend the tabs slightly, there is only one orientation which the metal tabs will make contact, you can’t screw it up. Once you are happy with the fit, solder in place.

Step 5: check for continuity and shorts with a multimeter and screw connector back together. I added some heat shrink as an extra measure of security and that’s it.

Hope this helps!
de Rich (KQ9L)

6 thoughts on “Rich builds a simple GX12 key/paddle adapter for the Discovery TX-500”

  1. I read Vlad’s original article and thought that I must get the pieces and give it a try when I get a chance. Terrific to see Rich’s success too.

    I see some enterprising soul marketing these – I’m sure there will be a demand too – Ideal to keep a spare in the field radio pack…

    Richard M0RGM

  2. The connector choice was one issue I had with the TX500, they are so different than other rigs. They do use very good connectors, but would prefer 3.5mm as most all others use.

    My builds most often have to do with the power connector. I have adapters for various connectors so I can plug my rigs into many power sources.

    But really should pay attention to the rig, how it performs.

    73, ron, n9ee/r

  3. I suppose you could do the same for the mic/speaker connector if you were only going to be activating with CW, to add in a 3.5mm connector for headphones only?

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