The AM Forum

Got a bunch of AN/GRC-9 transmitter receivers in the shop that I am working on, early fifties technology that was intended as a field or vehicle radio and covers 2 to 12 MHz They make about five or six watts in AM and around fifteen on a good day in CW. The transmitter uses a 2E22 tube in the PA running suppressor modulation and produce ok AM with a T-17 microphone. The one in the picture is a French copy of the US set but mostly US manufacture. The receiver’s passband is wide enough to drive a fifty-five Chevy through. Figure they did that because it doesn’t matter if the other stations were off frequency or not you would still hear them.

Hi!

I have a GRC-9 that I use probably once a week or more, CW (80-40-30 m) and som AM on 80 & 40 m.
With the TX in Band 3 at the high end, I get surprisingly high power levels, more than specs.
In both CW and AM, and the AM sound fine, as AM sounds using a T-17 microphone that is...
It modulates well, is without screaming...

I use it with the DY-88 power supply set at 12 V. (can be set to 6-12-24 volts)
My GRC-9 is made by Telefunken and the face plate is in German...of course.
As far as I remember, it was overhauled in the early years of the 70's, not sure why, it's has never been used.
The previous owner bought it "in the box".

Sometimes I use the LV-80/GRC-9 "afterburner", then I get around 100 W on CW.
The LV-80/GRC-9 is made by Hagenuk, it comprises two parts PA and PS, the latter is feed by a 24 volt system.
PS is a transistorized unit while PA is tubes 2x 6159.

The receiver is...yes it is wide...

Just put the video of one of the AN/GRC-9 that I have been playing with. There were many produced and many more options for powering by AC, Dry Battery with hand crank and Vehicle. Somehow get the feeling that the GRC-9 was something like the PRC-25/77 of its day.


https://www.youtube.com/watch?v=ekwSnH5sfbw

GRC-9 with the accessory M38 makes a fabulous package.  The PE-62 generator sometimes gets picky.

GRC-9 with MT50 mount

Looking Sharp! I have a M151 MUTT but its not much to look at, Next step up for you would be a GRC-19 (T-195/R-392) and that way you can run 100 watts of AM from the M38 My M151 has a GRC-106 that can run a couple hundred watts in SSB or fake (USB plus carrier) AM, attached is a picture. Life is too short for low power operations!

The GRC-19 in a lowly 60 horsepower M-38 is a real commitment.  It’s like driving around with two big guys in the back seat and another sitting on the hood for the 100amp generator.  But, that -19 is an awesome radio setup. The one I put together now resides somewhere up in NH.  
The Mutt and M38A1 with their blistering 70+ horsepower really made a difference in what the jeep could handle.

Back about 8 years ago at the DeAnza College electronics flea market near San Jose, someone brought at least half a dozen depot reconditioned DY-105 power supplies for the GRC-9. This is the 24 Volt only unit but the price was quite cheap and a bunch of us bought them.  I bring this up just to mention that there is still stuff out there waiting to be found.

My GRC-9 is in the queue waiting to be overhauled and checked.  I am curious how much chirp there is on CW, maybe SM6OID can comment.

I bought a cable from Fair Radio Sales, one of the French cables, and amazingly the thing self destructed about two years later, as in the rubber hardening and falling off the jacket and otherwise totally rotting. I am rebuilding that with some new old stock military cable that looks almost the same but has remained fresh.

I wasn't planning on using a T-17 mike as so many (all?) are quite dead these days.  I was going to use a Navy style RS-38 instead or maybe a modified T-17 with an electret cartridge hidden inside.

Hej!

The chirp is noticeable, but not horrible.
Well it may be a matter of definition?

I have NOT tested this, but I suspect that the type of power supply playa a role?
I use a DY-88 at the 12 V setting, actual supply voltage is approx 14.5 V minus drop in the feed cable.
Hence, I would expect more chirp at 6 V supply voltage and less at 24 V, but I have not tried 6 or 24 V.

A modification I made was to keep the filaments lit at AM, otherwise there is a really irritating delay when pressing the PTT.
It's a matter of adding a short jumper, could be removed easily should the need for pure original condition arise.

For AM I use a T-17 mic, it modulates very well without screaming, normal voice will do fine! Modulates close to 100%.

Have had my GRC-9 for probably more than 10 years, two problems had to be fixed, one tube in the RX needed to be replaced and the cable between PS and transmitter had to be "replaced".
The latter gave some weird problems, intermittently. But quite quick I understood were to look, opening up one of the connectors, and yes total rubber rot.

I like the GRC-9, small and easy to use, how ever... the receiver is wider that what I would like.

On the AC power supply it has a chirp but no worse then most tube transmitters of the day. it will do full break in and that's useful, and yes the receiver bandwidth is a issue but once again within the context of when thees things were built as long as you are not trying to compare with a modern rig its a good radio.

additional thought, being i just went thru four of thees things. If the 0C3 is bad that causes a chirp. the tube should glow all the time with vibrator or AC power supply. I was surprised to see how many i had turned out bad that were New Old Stock still in the box. 

The last time I saw a power supply for my GRC-9 it was being bought by someone at a military vehicle show about 20 years ago. I never could find one, so I ended up building one. I guess I have not actively searched for one either in a long time I must admit. I have at least one good T-17, and the audio improves if it gets a good rap or 2 on the benchtop, as you all probably know. :D
Larry