Feldfernsprecher 33 (original) (raw)

German Field Telephone Equipment Reference

Feldfernsprecher 33 / Field Telephone 33

Description

The feldfernsprecher 33 or FF33 is the standard German field radio of WWII. It is a general purpose field telephone designed for wired communications. It was introduced in 1933 as a modern replacement for the previous WWI legacy field telephones. It can also be connected to the Torn. Fu. D2 and Torn. Fu. Bl, and F series radio sets as a remote handset.

The phone case is 28 cm x21 cm x 10 cm and weighs 5.84 Kg.� The phone is made of the following components: a PTT (press to talk) handset, switchboard patch cable, generator crank, shoulder strap, 1.5 volt battery and internal framework for the telephone components. �Accessories available are: headphone (kopfh�rer) and throat microphone (kehlkopf). Used with the headset and throat microphone was mainly for use by switchboard operators.

The set is housed in a bakelite plastic case which consists of two parts is hinged and fastened with press to release spring latch. On the top of the upper case are two white panels. The panel on the left is used to record information such as call signs or station number while the panel on the right is inscribed with the German phonetic alphabet.

A dust cover on the front can be swung open to give access to two jacks; both jacks are common and also common to the with the incoming line terminations on the top of the phone. The jacks are used when patching two phones together or when connecting a field phone to an exchange line via an exchange line adaptor. The grill on the front of the case is designed to enhance sound of the ringer. On the right side of the case is another access plate which protects the port for installing the crank onto the generator. Sockets are located on each side of the lower case along the edge for installing a carrying strap.

Looking down into the phone you�ll see the following: The handset rests on top and when the phone is open it is convenient to lay the handset in the open top. Inside the top is a leaf spring that holds the handset in place when the phone is closed[1]. The battery compartment is on the end, covered with a hinged lid. Beside the battery box is an open compartment where the patch cable and the handset cord are stowed.

The handset plugs into a center jack console with a unidirectional plug. Beside the plug are two screw terminals marked Lb/Eand La. La is line and Lb/E is ground or in alternative mode of connection; a single conductor local earth ground. While this mode of communication allows two separate circuits using only one cable pair, it is open to interception from local earth listening devices. It also makes quality of communications dependant upon the local grounding quality.

On the right side of the panel the white generator test button (Pr�ftaste). Shorting the screw terminals and pressing the Pr�ftaste button while cranking the generator will sound the local ringer as a test of the generator output. The generator outputs of 84 volts AC as ringing current. Adjacent are the jacks for headphones. The generator crank is stored in a hole and notch next to the panel.�

In the field, when set up for use, the top cover is usually closed and the line and handset cord run out of the unit by the end of the case near the battery box. A pair of soft rubber strips built into the case cushions the cords when the lid is closed. The handset can then be laid crosswise on the closed cover. �The photo to the right shows the j�ger talking in the handset of a W28 telephone while the FF33 has its handset resting on the top of the closed case. A special accessory is available that creates a resting cradle for the handset on the closed lid. This was normally used with a switchboard setup and not in the field.

The telephone has two circuits, one is the ringing circuit which temporarily connects the generator with the ringer via the telephone line with ringing current. The other a talking circuit for communications is the other and is powered by the local battery when the PTT in the handset is pressed. When each station transmits, that only station�s battery is used, this minimizes battery drain and maximizes battery life.

To make a call after connecting the telephone, open the generator crank cover on the end of the phone, screw the crank onto the threaded shaft. Crank the generator a few turns, this will send ringing current to the telephone or switchboard at the other end of the line. Pick up the handset and listen for when the distant station answers. To transmit press the PTT and speak, release after speaking.

Operation

Telephone to Telephone Connection

The simplest field telephone setup is a point to point operation. This can be set up quickly and is usually used to enable a forward outpost to communicate back to the front line or a command post (CP). The configuration is two FF33 telephones and a one pair line between the telephones[2].

The line between the points can be run using a hand cable reel or backpack wire reel for longer distances. The cable can be run from CP to the outpost or the reverse, the wire reel is left at the destination since the connection to that telephone will be made directly to the termination at the reel. The other telephone will be connected at the origination of the line run.

The line pairs will be marked to indicate which lead of the pair is earth (ground). The earth end is connected to the screw terminal marked Lb/E the other is connected to the La terminal. At the other end of the line the same connection is made.

Achtung! In the heat of action a careless j�ger can very easily snag the incoming line, which will pull the telephone off the table, you will always snub the incoming line to a solid object. This is the first step before attaching the incoming line to the telephone. It is far better to snap the line than smash the 70 year old telephone.

Once the telephones are connected a communications test should be run. The outpost rings the CP and requests a test count. Once the outpost test is complete the CP rings the outpost and requests a test count. This tests two wayringing and talking. This also reminds the outpost to take steps to muffle the ringer if needed. Wrapping the telephone in a blanket or a zeltbahn is an effective method of reducing the volume of the ring.

Multiple telephone to telephone connections can be set up feeding back to the same CP. Using the patch cable each point to point connection can be jumperedtogether for a three way or greater connection as shown in this diagram:

Telephone Net Switchboard Operation

In a larger field situation a telephone net with a central switchboard[3](klappenschrank) is employed. Switchboards are usually the 10 line (klappenschrank zu 10 Leitungen), or the 20 line variants (feldklappenschrank zu 20 Leitungen).

To the left is an example switchboard setup. The telephone interface[4] (Amtszusatz 33) is attached to a 10 line switchboard (Klappenschrank zu 10 Leitungen) with two FF33s. This makes for a nice command post communications setup.

When a switchboard is employed all lines run directly to the switchboard and all call connections are controlled by the operator.

Below is an example field arrangement of field telephones, lines and switchboard. Operation of the telephones is performed in the same manner. The only difference is when in placing a call the operator will answer and you must tell him to whom you wish to be connected. The post you are calling from will be known to the operator as the line will be marked on his switchboard.

[1] If the phone is closed improperly it is possible to snap the bridge of the handset, care should be used in closing the phone with the handset in the cradle. Alwaysmake sure the larger microphone end of the handset is in the depression opposite the battery end.

[2] Communications begin to degrade if the line length is over a kilometer.

[3] Detail and operation of switchboards is described in detail in the switchboard technical document.

[4] The telephone interface allowed the switchboard to connect into and dial regular German Reichsposttelephones used in military offices and other locations.