From the mists of time ...
I am working through another box of my 'telephone bits & pieces', along with ALL the other stuff that needs to find new, caring folk who are interested in "how things used to be"
This is a receiver capsule which sits inside the part of the handset which is pressed up against your ear.
Not an early model with the metal circular disc on top but from the 1970's ~ 1980's era
These receiver capsules didn't often give problems but they did have a habit of 'disappearing' when inquisitive subscribers would unscrew the cap and remove the capsule, making the telephone pretty useless.
Telephone Instrument Handset SPARE PART
Receiver Capsule
Technlogy: dynamic
Type: 4T
Identification printing is ...
FRONT:
4T C/1/57
REAR:
DRG 96550
DIMENSIONS:
46.35mm diameter x 16.75mm thick
Screw down terminals (standard 'telephone issue')
TESTING:
My testing is purely DC, but I also connected the capsule to a low power audio amplifier to check it was producing audio.
DC resistance: 20.9 Ohm
Inductance: 5.5mH
Audio test with the LP amplifier was fine, quality is a bit "how's ya father" but that is to be expected, these were designed with a frequency response in the range 300Hz ~ 3000Hz for communications. I actually have two of these 4T's and the audio quality is better with this capsule, perhaps a 'later release' ?
COSMETIC CONDITION:
USED
CLEAN
NO damage to the metalwork
NO damage to the terminals
A little discolouration to the rear, showing as something like a white oxidisation but it does not affect the operation of the capsule. Perhaps the user of this handset had a dribbling problem?
Sterilised the whole capsule of course (iso alcohol)
I have now packed the capsule into a clear sealed plastic packet.
