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Fullerphone start page Various models Superposing Unit

Fullerphone

Using the Fullerphone.

(How to bring your Fullerphone back to life again)

Although the practical use of a Fullerphone is nowadays very limited or actually nil, it is great fun to get it running again as this usually takes very little time (unless the Buzzer-Chopper is not working and has to be opened). Assumed is that you have a Fullerphone of either Mark IV, IV*, V or 6, all employing a Buzzer F Mk. II.

A word of advice, check whether your Fullerphone has the proper model of Buzzer-Chopper, it should be Buzzer F, having THREE contacts, and not the very similar looking Buzzer T which was used with Telephone Set D Mk.V and having SIX contacts!

First, open the battery compartment on the left-hand side of the Fullerphone and connect two 1.5 volt dry batteries as indicated on the instruction plate in the battery compartment lid. For normal use only one battery (buzzer battery located at the rear) will do. Short-circuit the L1 and L2 terminals on front of the Fullerphone with a small piece of wire, unlock BUZZER and CHOPPER contact screws and unscrew them about 5 turns.
Insert the headphones (if not a proper C.L.R. or D.L.R. model of headphones is available, any LOW RESISTANCE model will do). With the PULL-ON knob out, press the Morse key and advance the CHOPPER contact screw (right hand side) until a click is heard in the headphones. Lock this contact screw loosely and tap the key to make sure that clicks are still heard. With the key pressed, advance the BUZZER contact screw (left hand side) until a loud and clear buzz is heard in the headphones. Lock the contact screw loosely and adjust both contacts if necessary when the tone is not perfect.
The potentiometer circuit may be tested by setting the reversing switch to A or B and a buzz should be heard in the headphones, which will vary in strength as the potentiometer is turned. The Morse key should not be operated during this test.

To test the incredible sensitivity of your Fullerphone, replace the short-circuit wire for a 200kOhm resistor. Signals should still be heard when pressing the Morse key.
Another experiment can be made by connecting any type of headphones to contacts L1 and L2. Neither a buzzer tone nor a key click should be heard!

Fault finding
If a Fullerphone has been stored for many years, it is very likely that some of the contacts of the potentiometer switch, the buzzer contacts and of the Morse key have been corroded.
- Pull the on-off switch. The buzzer should work (see set-up procedure above) and heard in the headphones when the Morse key is depressed.
- Measure the battery voltage over the make and break contacts of the Morse key. - Measure the battery voltage over the left and centre buzzer-chopper contacts after having removed the buzzer-chopper. - If both are in order Clean the Morse key contacts if necessary.
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Circuit diagram of Fullerphone Mk. IV* which is quite similar to the pre-war Mk. IV model but modified with RF filtering added. (C4-C7 and R1/R2)


Operators Working Instructions Card

This Working Instructions card was issued to operators of Fullerphones Mks IV, IV* and IV**. Note that this Mark IV model has "Receivers Headgear C. L.R. Double Mark III", which has a metal headband allowing it to be stowed in the lid of the wooden case.

Wireless for the Warrior
URL homepage: www.wftw.nl