Sonotone Model 300X Transistor (Body) Hearing Aid
The Sonotone Model 300X transistor body hearing aid was manufactured
by Sonotone Corp in 1965.
The stainless steel case measured 3⅛" by 1⅜" by about 11/16" thick and
weighed 3 oz without the batteries. It had a brown plastic insert on the
front and a shiny hard brown plastic lower front.
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Top view of the
Sonotone 300X transistor hearing aid showing the volume control (left
rear),
the 13-slot microphone grill (front center) and the 3-position off-on-t-coil switch (right).
This hearing aid may have been the first to have a ceramic microphone. |
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Left side view of the Sonotone 300X transistor hearing aid showing the
"Bi-Focal" switch (upper left of center). It appears this switch set the
hearing aid in either regular or high-power mode. The model 300X was a
higher powered version of the model 300.
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Close-up of the Sonotone 300X hearing aid receiver cord plug and
receiver cord jack (center) showing the 3-prong plug and jack. Sonotone
used this 3-prong plug arrangement on both the hearing
aid body and the receiver.
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View of the battery compartment of the Sonotone 300X transistor hearing aid with
the batteries removed.
This hearing aid took 2
No. 401 ("N") batteries.
The inside of the battery cover shows the
model number and the legend for the bank of 5 tiny controls lying immediately
above the upper battery.
These controls are
discrete-position sliding switches. On the left is the 2-position "LO"
low-pass filter control labeled "2", "1". The second 2-position "LVL"
control is label "H", "M". The center 2-position "HI" high-pass filter
control is labeled "B", "A". The fourth 2-position "AVC" control
(automatic volume control) is labeled "T", "U". On the right is the
3-position "POWER" control labeled "P", "R", "S".
To set them, you put a pen in the hole and slide the control to the
position you want.
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View of the Sonotone 300X transistor hearing aid in its case. |
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The Sonotone logo on the inside lid of the Sonotone 300X transistor
hearing aid case. |
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Outside view of the case of the Sonotone 300X hearing aid.
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