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Phones PTT T65 →
The shape is based on the 1965 design of the
standard Dutch dial-operated T65 telephone set from the
German manufacturer Krone, hence the name T65-TDK. The suffic 'TDK'
means Toon-Druktoets-Keuze (touch-tone dialling). It used
Dual-Tone Multi-Frequency (DTMF) signalling.
The T65-TDK was only suitable for subscribers who were connected to a
computer-operated switch that was capable of handling DTMF tones,
which excluded part of the country at the time. Furthermore,
PTT
charged a one-off fee to each subscriber for enabling the use of
DTMF tones.
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The T65-TDK was first manufactured in 1974 by Ericsson,
followed
in 1977 by NSEM and in 1979 by Krone. The DTMF units of
Ericsson
and Krone are interchangeable, but the one from NSEM is not, as its
keys are positioned differently. As a result, the grey upper case shell
is also different.
The sets were available in grey, green,
orange, red and brown – with different colour accents –
and were in production until the mid 1980s, when they were succeeded
by new slimline designs.
Apart from the numbers 0 to 9, the DTMF keypad has two additional
characters – ✱ and # – which gave access to a range of (switch-dependent)
options, such as wakeup call, answering service, follow me, etc.
In the Netherlands, most of the extra features were initially disabled by PTT,
and only very few features were eventually released to the public over time
(for additional fees).
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- Earth button
Initially, the T65 was available with and without an Earth-button,
that connected the A-wire of the telehone line briefly to ground,
to pass a call to the (optional) PABX. From 1973 onwards,
the earth-button was present on all T65 units.
- Colour
The initial colour was (green-ish) grey with a cream bottom, dial and
other details. In the 1970s, the phone also became available in a variety
of colours, including red, green, white, brown, blue and orange,
some of which are very rare today.
- Lock
A lock could be added – in the front left corner – to block outgoing
calls. It shorted the contacts of the dial, and
incoming calls could be answered as usual. Despite the lock, outgoing
calls were still possible by tapping the hook switch in the correct
rythm.
- Volume control
Handsets were available with an integrated knurled knob, that could
be used to adjust the volume of the additional built-in amplifier.
- Microphone amplifier
An additional microphone amplifier could be added for people with a
soft voice. It had to be enabled with a small black slide switch at
the rear of the handset. This option is rare.
- Mute button
Handsets were available with a push-button that disconnected the
microphone as long as the button was depressed. It was
located at the same place as the volume control (above).
The green variant of this option was also used on the
NATO KF 4-2 voice terminal.
- Noise-cancelling microphone
For use in noisy environments, such as aboard ships and in military
bunkers, a special
noice-cancelling microphone
was available. It was
fitted instead of the regular microphone and was slightly thicker.
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For the conversion of standard T65 telephone sets
to touch-tone dialling,
circular DTMF units were made by Ericsson.
These were particularly useful for the W65 and I65 models, which were not
available in a DTMF variant as standard.
It has the same form factor as the old interruptor (pulse) dial, so that it
could be retrofitted to any existing T65, regardless
the manafucturer.
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Red a Line (A) Blue b Line (B) Green E Earth (ground) Yellow EB Extra bell (strapped to b in wall socket)
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Red T Speaker (1) Blue T Speaker (2) Yellow M Microphone (1) Green M Micriphone (2)
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a Subscriber line (A) red b Subscriber line (B) blue EB External bell (normally strapped to b) 1 GND Ground
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The (EB) terminal is normally strapped to (b) terminal inside the
wall socket. It is removed when an external bell set is connected to
these terminals. If the phone doesn't ring, check whether
this strap is present.
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- Ericsson
- Krone
- NSEM - Nederlandse Standard Electric Maatchappij BV
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© Crypto Museum. Created: Thursday 30 March 2017. Last changed: Monday, 15 January 2024 - 16:20 CET.
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