Here are a collection of diagrams documenting the pin-out and design of several common interface cables used to connect your node radio.
The Clansman PRC350/1/2 Interface cable
Arguably one of the most popular configurations is to use a Clansman PRC35x as your node radio and use a 2nd 350/1/2 to talk through. Currently the 351 is probably the most commonly used military node radio on MilNet and this diagram shows you how to make the interface cable you will need so you can use a dedicated 350/1 or 2 to act as your node radio. The 7 pin Clansman plug in this diagram is actually from a standard 50cm long Clansman audio cable and it plugs straight into the radio. You could of course use an old clansman telephone style handset cable and just cut the handset off leaving the full length of cable and plug still attached.
You'll need to buy the Radio Arena Interface Version 3 cable from here or an alternative online retailer. It's important to note that the cable colours are correct on the Radio Arena cable and you will find several other colours and wires in each cable when you peel back the sheath. The cable colours on the Clansman plug part of the diagram are the colours of the actually original wires inside the clansman cable.
Icom IC-7300 Interface Cable
Another very common radio to use as the node radio is the Icom 7300. This enables HF communications over MilNet and is the go - to method of using the Clansman PRC320 HF Radio on MilNet. It's very important to know that you must use the squelch on the node radio otherwise you're EchoLink will only transmit and never receive. For best audio use AM and set your squelch quite high to ensure EchoLink knows it can transmit when the carrier is closed by the squelch at the end of the over. All the same setting apply, just be careful not to send any squelch burps through the network please!
This solution uses the ACC Socket on the back of the 7300 so you don't need to remove the Mic. All new 7300's are supplied with the 13 Pin Din plug and pig tails adapter and this particular diagram shows the correct colours of those pigtail wires attached to the plug. If you no longer have the ACC plug for your radio, any standard 13 Pin Din plug will suffice and you just need to follow the pinouts.