The J-45 was designed for mobile use such as in a Jeep, plane, tank, etc. It could also be used on a desk as the key is on a hindge that allows it to swing out away from the leg strap and lay flush on a hard flat surface. J-45 key's were made by several different manufacturers. These types of keys were in use from WWII up through the 1970's and possibly later.

According to The Vail Correspondent #5 January 1993: A J-37 with stock number 3Z3437-2 had a leg band assembly. A J-37 with stock number 3Z3437-3 had a leg band assembly and a cord and was black enameled.

Where does the J-45 name come from?

The short answer is the leg strap. Remove the straight key from the leg strap and it is no longer a J-45. Now for the longer answer. It was the U. S. Signal Corps that assigned their telegraph keys with the letter "J" and then a number. This practice started during the WWI era and ended in the 1950's. According to an article by W1IMQ in the The Vail Correspondent #4 July 1993, before 1943 both the Army and Navy had separate nomenclature systems. In 1943 these separate nomenclature systems gave way to the Joint Army Navy nomenclature system(AN System) for all new equipment. Although existing items continued to be made and marked under the old system. The AN nomenclature is known today(1993) as Joint Electronics Type Designation System(JETDS). Under the JETDS nomenclature keys and other keying devices carry the unit indicator KY. Thus the Signal Corps J-45 leg key became known as the KY-116U and KY-562/U. The Vail Correspondent goes on to note that the J-number keys range from 1 to 51. Excluded in that list are the J-8, J-9, J-13, J-39, J-42, J-49, and J-50. According to the book J-Series Telegraph keys of the US Army Signal Corps by Larry Nutting he states that J-49 seems to be an AC motor driven “Automatic Keyer” used with the BC-751. And he notes that J-13 and J-39 appear in a 1946 Signal Corps listing of type-numbered items, but that further information is unavailable. Lastly, according to The Vail Correspondent #10 January 1995 the proper nomenclature for the Signal Corps closed circuit key alone, without a base, is J-30 and is described as being for "general purpose application". 

The picture on the left shows the markings found on the J-37 key .Just to the left of the lever is "J-37" and to the right of the lever is "JFC". The JFC marking indicates that the key was made by the company "JFC. Elex INC". 

The photograph on the right is of a metal sticker that is found on the side of the leg clamp. The sticker reads as follows, "KY-562/U". I do not know when this J-45 was manufactured but J-45's found with the marking KY-116U are post WWII according to Tom Perera's(W1TP) Telegraph Collectors Guidebook.

Where did the KY in KY-562/U come from?

According to an article by W1IMQ in the The Vail Correspondent #4 January 1993, before 1943 both the Army and Navy had separate nomenclature systems. In 1943 these separate nomenclature systems gave way to the Joint Army Navy nomenclature system(AN System) for all new equipment. Although existing items continued to be made and marked under the old system. The AN nomenclature is known today(1993) as Joint Electronics Type Designation System(JETDS). Under the JETDS nomenclature keys and other keying devices carry the unit indicator KY. Thus the Signal Corps J-45 leg key became known as the KY-116U and KY-562/U.

The picture on the left is of the J-37 attached to the leg strap.  When the J-37 key was configured in this fashion it was known as the J-45. The J-45 configuration was used in military aircraft and tanks, and probably found its way into some amateur radio mobile installations as well.

The photograph on the right is of the inside hinge area of the J-45, the key's knob can be seen at the far left.. The hinge can be seen on the right.

These next pictures show the top and bottom of the J-37 key removed from the leg strap.

J-37 Key

The good ole J-37 key served with the U.S. military during WWII, the Korean War, and through-out the Vietnam era. The J-37 key was the real workhorse during those years and carried the bulk of the action. The J-37 key has been built into many numerous and different configurations with the addition of different bases. One of these different styles is the J-45 in the pictures above. Where does the J-37 name come from? Well, it was the U. S. Signal Corps that assigned their telegraph keys with the letter "J" and then a number. The J-37 key's were made by several different manufacture's. According toThe Vail Correspondent #5 January 1993: It should be noted that the J-37 did come with its own unmarked base(Signal Corps. stock number 3Z3437-1). This base is cut away on the sides and shaped like the letter "I". It originally came with the AN/GSC-TI portable code training set which had 10 keys each in their own slot. Each key came with a 10 foot cord which was wrapped around the base(the reason for the cut away sides on the base) for storage. To view one of these J-37 keys please click HERE .

Where does the J-37 name come from?

Well, it was the U. S. Signal Corps that assigned their telegraph keys with the letter "J" and then a number. This practice started during the WWI era and ended in the 1950's. According to an article by W1IMQ in the The Vail Correspondent #4 July 1993, before 1943 both the Army and Navy had separate nomenclature systems. In 1943 these separate nomenclature systems gave way to the Joint Army Navy nomenclature system(AN System) for all new equipment. Although existing items continued to be made and marked under the old system. The AN nomenclature is known today(1993) as Joint Electronics Type Designation System(JETDS). Under the JETDS nomenclature keys and other keying devices carry the unit indicator KY. Thus the Signal Corps J-45 leg key became known as the KY-116U and KY-562/U. The Vail Correspondent goes on to note that the J-number keys range from 1 to 51. Excluded in that list are the J-8, J-9, J-13, J-39, J-42, J-49, and J-50. According to the book J-Series Telegraph keys of the US Army Signal Corps by Larry Nutting he states that J-49 seems to be an AC motor driven “Automatic Keyer” used with the BC-751. And he notes that J-13 and J-39 appear in a 1946 Signal Corps listing of type-numbered items, but that further information is unavailable.

The J-37 key in any of its configurations is a fun key to use. It is lightweight, portable and simply stated, as tough as nails. The J-37 key incorporates a leaf spring design that many folks find a pleasure to operate. Some believe that this leaf spring design gives the operator a smoother feel of the key over that of a coil spring design such as the J-38 key. The mechanical characteristics of the leaf spring, to some CW aficionados can not compare to those of the coiled spring design, even when modern keys such as a recently manufactured Nye Viking Speed-X CW key is used.

To view a J-37 key configured as a J-47 please visit HERE .

To view a J-37 key on a J-37 base please visit HERE .

References:

Tom Perera's(W1TP) Telegraph Collectors Guidebook

Tom Perera's(W1TP) Telegraph Collectors CD-ROM

The Vail Correspondent #4 July 1993

The Vail Correspondent #5 October 1993  

The Vail Correspondent #10 January 1995

J-Series Telegraph keys of the US Army Signal Corps  by Larry Nutting(K7KSW)