Dahlberg Model T-1 "Tonex 1" Vacuum Tube Hearing Aid
The Dahlberg Model T-1 (Tonex 1) was the very first hearing aid
produced by Dahlberg Electronics, Inc. of Minneapolis, MN. It came out
in December, 1949.
The next year, in December, 1950, the T-1 (Tonex 1) was renumber as
the D-1 and called the "Tru-Sonic".
The Tonex 1 was a
one-piece 3-vacuum tube hearing aid. Without the batteries, it weighed
3.3 oz. (94 g). It measured 2 11/16" x 1 13/16" x 13/16" (6.8 x 4.6 x
2.1 cm).
The case was made of sterling silver with a gold-plated? pocket clip.
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Front view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid.
The gold-plated? microphone grill dominated the front view.
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View of the microphone of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid.
It was unusual to have the microphone outside the body of the hearing
aid as was done here. In this case, the gold-plated? case housed the
microphone.
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The microphone housing of the Dahlberg Model T-1 (Tonex 1) vacuum tube
hearing aid doubled as the pocket clip.
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Top view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid
showing the two controls. The on-off/volume control wheel is in the
center and below it is the round knob of unknown function. The two
silver case halves slid in grooves in the black chassis. They no longer
fit well hence they come apart (as seen on the right side).
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Side view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid
showing the round receiver jack. The receiver cord and receiver are
missing.
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Rear view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid.
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Bottom view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid
showing the only identifying mark. Very faintly, in the center of the
bottom is the word "TONEX". It's so faint it's easy to miss it, even
when looking for it. |
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View of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing aid with
the back cover removed showing the 3 vacuum tubes (upper right). The "A" battery
position is
the middle left (under the round hole) and the "B" battery
position is at the bottom. |
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Close-up view of the Dahlberg Model T-1 (Tonex 1) vacuum tube hearing
aid showing the battery compartment.
The 1˝ volt "A" battery was the
Mallory RM-1 (or equivalent). The "A" battery was pushed up the left
side until the spring clip snapped up to hold it in place. To get the
"A" battery out to replace it was a bit tricky. You had to hold the
spring clip down and then insert a screwdriver or something in the hole
to push the "A" battery out.
With the "A" battery in place, the 15 volt "B" could be inserted
across the bottom. This hearing aid used an
Eveready No. 504E battery (or equivalent). |
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