22 February 2023


 Boy, this picture brings back memories.

I grabbed this screen shot from a video posted on the Vintage Military Radio group on Facebook. It's a surplus AN/GRC-106 HF radio in its vehicle mount. These radios were in regular use in the Army well into the 1990s. The transceiver is on the bottom, the amplifier is on the top. What you don't see is the power supply or hook-up to the vehicle's 24 volt power system. The power supply is as large as the amplifier section.

I had one of these in just about every unit I was assigned to when in the Army, and when filling a command position I had to inventory and maintain these things. The transceiver/amplifier stack you see in this image is, easily, 150 lbs of mid-20th century military radio technology.

Without the amp you'd get 20 watts of output on USB. With the amp, it was (if I remember correctly) 400 watts of output. When you keyed up, and all the cooling fans kicked in, it sounded like a tornado was in the room with you.

In the late 80's I was assigned to the 864th Engineer Battalion at Fort Lewis, WA. We had one company stationed at The Presidio outside of San Francisco. Once a month we'd set up a GRC-106 at both locations and run communications exercises using different antenna configurations. I didn't have my ham radio ticket then, but our battalion commo chief did, and I remember him mentioning that you could use these radios on the ham bands. I thought that was really cool.

Years later, after I got my General ticket, I was working at Fort Bragg, NC as an exercise evaluator. Late one night I was in a company TOC (tactical ops center) and they had their GRC-106 set up and running. I had no idea who they were supposed to talk to, because I knew the battalion TOC wasn't set up to work HF. I reached over and switched the radio to USB, cranked over to the 20 meter band and clicked around to see if I could pick up any ham traffic. There wasn't much going on, but I did hear one guy calling CQ. I keyed up and answered him back. He acknowledged my callsign but said my signal was very weak. Four hundred watts and weak? Something didn't add up. I went outside and traced the coax to the antenna which, to my surprise, was a HMMWV mounted VHF vertical whip. Someone clearly just went through the motions of setting up the radio to satisfy an evaluator ("See sergeant, we set up our 106 - can we get credit for that?"). At the time I was surprised I didn't burn out the transmitter finals. Later I remembered that the amplifier had something like five tubes in the transmitter stage and could soak up a heck of a lot of SWR.

Today you can easily duplicate the AN/GRC-106's 'barefoot' capabilities with something like an Elecraft KX2, an Icom IC-705, or a Xeigu G90. But that's not the point, is it? The AN/GRC was a glorious piece of mid-20th century, Rube Goldberg-esque, military radio technology that was so well designed and manufactured it stayed in service for almost 40 years. So let's celebrate the AN/GRC-106 for what it is - an unapologetically over-built, over-complex, over-weight and dead reliable radio, and one I'd love to have running in my shack.

W8BYH out