(Louis Meulstee's web site)
Back to the home page of Louis Meulstee's "Wireless for the Warrior" web-site
Fullerphone
Various models and constructional details.
In this section is posted a variety of different Fullerphones, unfortunately no picture of a German World War 1 Fullerphone could be traced.
The manufacture of similar instruments in other countries, notably France, Italy, Portugal, USA, Holland, is noted.
In Germany and Holland the Fullerphone was called 'Geheim Telegraaf' (Secret or Secure Telegraph).
The Fullerphone is housed in an aluminium and steel case which is secured by guides in a wooden carrying case provided with a sling.
The headphones are carried in the lid of the case (Mk.I case only).
When the lid is completely closed, the Pull-On switch is automatically set in the Off position.
A spring stop which holds the Fullerphone unit in position in the carrying case must pressed down for the unit to be drawn forward into the operating position.
A second stop prevents the unit from sliding completely out of the case.
The buzzer-chopper unit slides into position on the top right-hand side of the instrument, the connections being made by three contact springs.
The Morse key is a Key WT 8-amp No. 2 which can be one of the myriad of versions which were produced at the war-time period.
The Fullerphone Mk. III was developed in late World War 1. It was the standard model in the inter-war years, until being superseded by the Fullerphone Mk. IV.
A telephone and calling buzzer facility are fitted in this model; these are of course not immune from overhearing.
Note the folding type Morse key in the bottom right hand corner of the case.
This model was already fitted with a potentiometer and reverse key.
Fullerphone Mk. IV * modified to Mk. V. Apparently all of the Mk. IV models have been enamelled black (the ones I have actually seen).
Later issued Mk. V and Mk. 6 models were usually light-blue/grey, although black cases have been noted.
The Morse Key is an early Key WT, 8-amp, No. 2 having reversed make and break contacts.
Fullerphone Mk. V was issued from mid World War 2 onwards. The Morse key is a Key WT, 8 amp, No. 2, Mk.II.
Other versions of this type of Morse key may be encountered.
Note that the Buzzer F can be easily removed from the Fullerphone.
Mechanically, this Fullerphone differs only in minor internal detail to the Mk.IV* in the previous picture.
Fullerphone Mk. 6 is a fully tropicalised version, enclosed in an immersion proof metal case. Electrically, it is identical to the Mk. V version.
Note the Headphones type DLR No. 5.
'Apparado da campo per telegrafia inintercettible - Mod 1931' (Apparatus, field-telegraph, non-interceptable - Model 1931)
The Italian Army copied the Fullerphone in the early thirties.
Its circuit is similar to the British design, though there is no line balancing adjustment potentiometer provided.
Wireless for the Warrior
