Czech Morse Key

Czechoslovakia Cold War Morse key. This page is asssembled from various opinions & photographs sourced from the Internet.

From: N1FN: Info on this key was kindly provided by Jan, OK1XU, who says "This key was (and, I think, still is) generally used in the Czech Army. It is part of the old field radio station "RM31" (many tubes and Xtals...). Many Czech hams learned CW by a means of this key, because these keys could be found in many radio clubs, at flea markets and so on."

"The key was made in the early 1950's for the Czech armed forces, presumably for the army. It was part of an HF base station which was called Type RM31 (although this may have been just the receiver reference) so the type name stuck and was then associated with the key. I now think the transmitter was called Type RS41. I have spoken to several Czech radio hams but they appear to know little about the keys history although many have used the keys."

OK1XU says: "This key was (and, I think, still is) generally used in the Czech Army. It is part of the old field radio station RM31 (many tubes and Xtals). Many Czech hams learned CW by a means of this key, because these keys could be found in many radio clubs, at flea markets and so on."

"I purchased my nice Cold War-era Czechoslovakian military "Type RM31" straight key in January, 2015. This key (code-name Radoslav) appears to have been manufactured in the 1950s for the Czech armed forces and was part of an HF station called the "Type RM31". My particular key was purchased in Germany by the fellow I purchased it from. The original two-pin connector has been replaced by a 1/4" monaural jack."

In the early 1950s Czechoslovakia stockpiled many Morse keys for their military. They remained in storage and pristine condition until the early 21st Century when they were released on to the market at 15. Many amateur radio enthusiasts still use and trade them on eBay. At October 2017 they're 40 Euros from Germany and Slovakia.

They were supplied with a stock label and wrapped in grease proof paper hence (despite some minor rust on the base plate) their excellent condition. They came with a two or four prong plug that connected to the TX/RX often installed in a truck.

Description Czech army Morse key known as the RM-31 Telegraph Key (Telegrafni RM-31 klic in Czech). This key is a part of the old field radio station RM31. The keying arm moves upward into a second position for receiving. There are labels on the front edge of the enclosure for the up or non-keying position "Prijem" (receive) and the down or keying position "Vysilani" (transmit).

The key measures 150 x 65 x 50 mm (5 1/8" x 2 1/2" x 2"). Weight is 470g (1.03 lbs).

Czech Key Construction If you look carefully at the photograph below with the parts as an exploded view you can see 2 springs. The conical one is the actual compression spring used to give the key its resistance when you push the key arm down. In a fully assembled key it is mounted under the pivot arm and you cannot easily see it unless you remove the top gap adjusting plate and screws. The tension spring you see when you lift the lid is nothing to do with key arm pressure at all. Its sole purpose is to take up any slack in the brass pivot bushes. The spring pulls the pivot assembly firmly on to the pivot pins. There is also a 3rd spring which is made from flat spring material. It is shaped to enable the arm to be clicked into the up position. I give credit to the person who designed this key for all the thought and effort put into it. The key is a dream to use and it really is a clever piece of design work.

I just wonder how much the key cost to produce. We can now all enjoy using the key for a very sensible price. Exploded view less cable and plug with top cover removed (broken off)..........I had to file and drill out the rivets to be able to separate the LHS & RHS arms of the key. The baseplate is easily removed just by removing the 4 countersunk screws, so if you buy a slightly rusty one you can soon clean up and repaint the baseplate.

Inside with top cover up...............the Bakelite case has brass bushes to support the pivot shafts.

The underside showing the connections to both key contacts and "key up" cam switch (red wires).........

If you want to be able to adjust the key with the top cover up, then link out the 2 connections at the LHS of the photo (i.e. link the yellow wire to the tinned wire).

"CZECHOSLOVAK ARMY morse telegraph key with original line and plug. Made of bakelite and steel: key knob made with black bakelite, the cross and other details made from steel and bakelite. Very well preserved and measures about 15 cm and weights 480 gr. The steel cross has two positions: UP to recieve (PRIJFM) and down to transmit (VYSILANI). After cleaning operations (no repair was necessary), it was only screwed to a new wooden base. Bought on "Collectibles Salesa" at Bohemia, Czech Republic."

Look carefully at these photographs to see how the key was deployed.

Tatra 805 - RM-31Ma Trinec (Typical truck to transport the key and radio equipment and in tanks?)

Notice how the two pins on the plug are different diameters so reversed polarity was avoided? Maybe... YMMV. Some older keys had a four prong plug to fit the older radios re move arm up for RX and down for TX but that was no longer needed for recent radios as the TX/RX was automatic. However, the recent radios still had four holes in case an older key was used.

Source: From kind & appreciated various Internet webmasters so please Google: 'Czech Morse key' thank you.