Need Help With WWII Era Aircraft Antenna Tuner
Quite few years ago I aquired this piece of gear from a woman that was selling off her father's estate. I put the thing away in storage some 20 years ago and just decided to pull the thing out and either try to use it or get rid of it (see photo below).
Unfortunatly I have not been able to find out very much about this Tuner. It appears to be WWII era and the I.D. tag says it is an "Aircraft Antenna Tuning Unit manufactured by the Aircraft Accessories Corporation." Also, according to the tag, it is a type 1001A and was made for use with the RC-52 Radio Transmitting Equipment. I have not been able to find much on the RC-52 either. As you can see in the photos the conductors inside are large and should be able to handle high voltages and currents. The controls on the front of the unit are labled "coupling, Tuning Inductance, and Tuning Condenser." You can tell that it is old by the use of the word "Condenser." The unit appears to be original and has not been modified as far as I can tell. The meter on the front is an Ammeter and is used to display RF Amps and has a full scale reading of 8 amps.
As I mentioned I can't find much about the unit online but another Ham friend said he though it is part of the BC-452 transmitter. The BC-452 transmitter was a 2 crystal 300 watt CW output on 1.5 to 7.0 Mhz. As mentioned the RF ammeter goes to 8 amps full scale. That is a lot of RF amps. 8 squared X 50 ohms = 3200 watts! If you just loaded to 5 RF amps antenna current that would be 5 squared X 50 ohms = 1250 watts! The military greatly reduced the ratings on any thing they used and as you can see it is very heavy duty. This would make a great tuner for 40 or 80 meters and can probably handle as much power as you can put to it!
I would like to find out more about the operation and specifications and perhaps get some documentation like a manual if possible. Maybe someone out there has seen and/ or used one of these in the past.
Tuner Outside.JPGTuner Inside.JPG
I suggest you go over to Robert Down's site at http://www.vendio.com/stores/wa5cab
Ask him if he can help you. He is very knowledgable about WWII radio gear and has a large collection of manuals.
I think it should be easily done to backwards engineer the circuit design. Not much to figure out in most AT's.
The 8A ammeter probably reflects the fact that most aircraft antennas were very short for HF, especially for 2 - 7 MHz. These antennas are usually very low resistive (2-10 ohms wasn't unusual) and of course high capacitive reactance (zeroed out by a loading coil). Not many hams realize that an RF ammeter makes a pretty low cost RF wattmeter, with a good dummy load and Ohm's law.
Looks like it is generally useable on the lower ham bands. You might have to add an SO-239, as most of the WWII gear used a single open wire and ceramic terminal posts. Look at a typical SCR-274 or ART-13 installations. Coax wasn't that widely used until after WWII.
Regardless of the manufacturer, I do not believe this is an aircraft radio. 1. It's too big 2. No aircraft of that era had radios capable of more than a hundred watts or so.
This is obviously designed for Open Wire Line (ladder) with impedance of say 300 to 600 ohms.
Give a it a bath, check it electrically and try it out. It's an antenna tuner with two coils (with goniometer adjustments) and a single cap. Hook up a radio and antenna and give it a try. You should be able to work out a table of approximate settings for each band. A noise bridge or 'tuner tuner' might help speed things along.
 p.s. It doesn't go with an ARC-52 radio as that was a Navy UHF radio series.
"RF gotta go somewhere!"
This post gets my vote for surprise qrz advertisement of the year.
Just what you need to use for feeding a BC-610 into a rhombic. That coil looks like it would loaf at a 1000W carrier on AM.