Military Equipment



R-388

The R-388 HF receiver was a Collins design that paralleled the 75A and 51J series of receivers popular during the late 1940's through the 1950's. The R-388 is actually the 51J-3 and has the single crystal filter for selectivity. The 51J-4 had Collins mechanical filtering installed which vastly improved the skirt I.F. selectivity.
It is fairly easy to install mechanical filters in the R-388 as an upgrade. The problem is finding suitable 500 KHz. filters for a reasonable price. As it stands, the R-388 provides full coverage of the HF range in one-MHz-wide bands. It makes a very useful bench receiver for testing and general shortwave listening.


Command sets

The Command Set series of transmitters, receivers, modulator, and accessories were produced in large quantities and used extensively by the Army and Navy during and after WWII. They were of basic design, but built to rigorous military specifications to survive use in fighter aircraft and small bombers. Hams have used them with reckless abandon since they were released to the public after the war. I have brutalized my share of them over the years, adding product detectors, modern connectors, and AC power supplies. Numerous transmitters were easily converted to the amateur bands providing power outputs between 25 and 100 watts from the 1625 output tubes.
"Unconverted" Command Set equipment is at a premium these days as the seeming limitless supply has dried up. Even the mangled units are being snapped up by collectors.


RAX

The WWII "RAX" receiver was sort of a band-switching Command Set and actually makes a usable amateur receiver when converted to AC power. I haven't attacked this one yet, but plan to spruce it up before too long. Somebody already began the job before I got it.


BC-224

The BC-224 was the 12 volt equivalent of the BC-348 used in aircraft. The high I.F. frequency of 915 KHz. resulted in a wide passband, useful in combat aircraft, but mediocre for amateur use. The modifications to these receivers to achieve better performance are second only to the Command sets above. Nonetheless, many novice operators successfully began their amateur careers with one of these.


BC-312N

The BC-312/342 series of receivers were built for the Army for HF communications in field vehicles. The single conversion superhet design is from the mid-1930's when these receivers were being developed and parallels the BC-224/348 units that were used primarily in AAF aircraft such as the B-24.
My unit was received as a "basket case" with a missing dynamotor, questionable modifications, and numerous dangling wires. Using an external power supply, I was able to straighten out most of the problems and in spite of the appearance, it does a creditable job on all bands with good volume and reasonable selectivity. There are some squeeks and squawks at some gain settings indicating that a few of the 65-year-old capacitors are in need of replacement.


HE-1

German HE-1 monitor receiver from WWII. These were a mechanical marvel of German engineering. The gear system driving the main tuning looks like a complex watch works. I have seen pictures of this used in conjunction with a DF loop antenna. Perhaps the unit was used to detect enemy transmissions or provide bearings for aircraft in the LF ranges.


94set

An excellent example of the Japanese type 94 field radio designed in the mid-1930's and used during WWII. Note the receiver and transmitter plug-in frequency units and the shiny code key that drops out of a slot in the upper right side of the front panel. The receiver is a regenerative design and the transmitter uses the Japanese equivalent of our type 807.


I have several plug-in units and various other parts for this beauty. I understand that there are only a couple of these in existence in the world.


I hope to power this up and make a few contacts on the 80 meter band one of these days.






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