Zenith Model A3A-B3A "Radionic" Vacuum Tube Hearing Aid
The Zenith Model A3A-B3A "Radionic" vacuum tube hearing aid was
manufactured by the Hearing Aid Division of the Zenith Radio Corporation
of Chicago, IL beginning in July, 1944.
The black plastic case measured 5⅛” by 2¾” by ⅞” thick, and weighed 8⅞
oz. without the batteries.
The microphone grill is the series of 9 horizontal slots (top center). Notice the large "Z" on the lower front face.
This was a two-piece hearing aid as it connected to external
batteries (battery cords bottom left). The magnetic receiver is at the
bottom right.
The Zenith Model A3A used three vacuum tubes. The third vacuum tube
likely supplied more power so this hearing aid could also drive
bone-conduction transducers. The "A" in the "A3A" part of the model
number refers to an air-conduction receiver, and the "B" in the "B3A"
part refers to a bone-conduction transducer. Thus, this hearing aid
could supply either mode. The unit shown here just had the
air-conduction receiver.
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Top view of the Zenith Model A3A-B3A showing the 4-position (2, 3, 4 and the
lever straight up for position 1) tone control (left), the large volume
control wheel (center) and the on-off switch (right).
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Inside view of the Zenith Model A3A-B3A showing tone control (left), the volume
control (center) and the on-off switch (right). The 3 vacuum tubes are
visible center left, lower left and lower right.
The two left vacuum tubes are Raytheon CK 505 AX models, while the
bottom right vacuum tube is a Raytheon CK 507 AX model.
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Inside view of the bottom part of the Zenith Model A3A-B3A showing
two of the vacuum tubes. Some hearing aid vacuum tubes, such as these,
did not have pins that plugged in a socket, but rather, their leads were
soldered in place as shown. The tube on the left (CX 507 AX) is a 1
7/16" x ⅜" wide (3.0 x 0.9 cm). The flattened thickness dimension is
9/32" (0.7 cm). The tube on the right (CK 505 AX) is 1 3/16" long (3.0
cm) with the same tube shape and diameter as the left one.
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Inside view of the Zenith Model A3A-B3A (left) and A2A (right) showing the
difference in size of these vacuum tubes in just 2 years. The larger
round vacuum tubes (right) from 1942 and the smaller, flattened oval
vacuum tubes from 1944.
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Close-up view of the Zenith Model A3A-B3A battery plug. The battery plug had
the heavy battery wires attached to it. In contrast to the 3-pin plugs
of the Model A2A, with the Model A3A-B3A Zenith made the battery plug
with 4 pins so there was no confusion which plug went where.
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Close-up view of the Zenith Model A3A-B3A receiver plug. The receiver plug
had the thin receiver cord attached to it.
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Close-up view of the Zenith Model A3A-B3A receivers and ear tips. The
pink
receiver (top left), the clear plastic ear tip post (right of receiver)
and the rubber ear tip (right of plastic post) all snapped together as
shown with the pink receiver and parts assembled (top right).
The Model A3A-B3A came with a variety of sizes of rubber ear tips (bottom
left) and a variety of sizes of ear tip posts (bottom right). |
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Close-up view of the Zenith Model A3A-B3A battery plugs. The 3-pronged plug
went into the "B" battery (left) and the 2-pronged plug fit the "A"
battery (right).
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View of the Zenith Model A3A-B3A hearing aid with both the "B" and "A"
batteries attached. This whole assembly weighed a whopping 1lb, 9 oz!
The
Zenith Z-30 "B" battery (left) put out 45 volts, while the
Zenith "A" battery (to the
right of the "B" battery) put out the usual 1½ volts.
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Back view of the Zenith Model A3A-B3A hearing aid. The pocket clip is at the
top center. The pocket clip could also be attached to the front via the two slots
(shown in top picture in the center of the microphone grill).
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Close-up view of the back of the Zenith Model A3A-B3A showing the
information engraved there. It reads, "ZENITH RADIO CORP. U.S.A.",
"BONE-AIR", "FOR USE WITH MODEL A3A-B3A" then gives patent info.
and the serial number.
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Then, as now, you had to return the registration card for the Zenith Model A3A-B3A "Radionic"
hearing aid in order to put the warranty into effect.
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The Zenith Model A3A-B3A "Radionic" hearing aid came out in
1944 and was being sold in 1945 as this receipt for the return of the
warranty registration card, dated Mar 10, 1945, attests.
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This handy reference card came with the Zenith Model A3A-B3A "Radionic" hearing aid.
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Rear view of the reference card that came with the Zenith Model A3A-B3A "Radionic" hearing aid.
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The Zenith Model A3A-B3A "Radionic" hearing aid in its original box. |
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View of the top of the Zenith Model A3A-B3A "Radionic" hearing aid box.
Notice that Zenith was up-front about the price of their hearing
aids—boldly putting the price ($50.00) on their boxes. This was
in sharp contrast to the other manufacturers who sold their aids for 3
to 4 times as much so didn't display their prices. |
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The Zenith Model A3A-B3A "Radionic" hearing aid's original box.
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