Microtone Model T-612 "Fleetwood" Vacuum Tube Hearing Aid The Microtone Model T-612 "Fleetwood" vacuum tube hearing aid was produced by Microtone Co. of St. Paul, MN in 1951. It measured 3" x 2½" x ⅞" thick and weighed 7¾ oz. without the batteries. This hearing aid had an elegant filigree microphone grill (top center) The shiny chrome front and back overlaid a very light blue plastic chassis. |  | Click picture for larger view | | |  | | | |
| Rear view of the Microtone Model T-612 "Fleetwood" hearing aid showing the manufacturer's name (Microtone) at the bottom. The whole back swung down to give access to the battery compartment.
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| Top view of the Microtone Model T-612 "Fleetwood" hearing aid showing the receiver plug (left), the "thumb groove" to open the battery compartment door (left of center) and the 3-position tone control lever (right) shown in the upright "HF" (high-frequency emphasis) position. In the middle "N" (normal) position both low and high tones were amplified equally, and in the low "LS" (low suppression) position low tones were suppressed and thus the higher tones were accentuated. The pocket clips are at the left and right sides (top). |  | Click picture for larger view | | | |
| Left-side view of the Microtone Model T-612 "Fleetwood" hearing aid showing the on-off/volume control wheel (upper left). |  | Click picture for larger view | | | |
| Right side view of the Microtone Model T-612 "Fleetwood" hearing aid showing the external microphone jack (center) and the external microphone flat-pinned plug beside it. External microphones weren't unknown in body hearing aids, but they certainly weren't common. |  | Click picture for larger view | | | |
The whole back of the case swung down from the top revealing the battery compartment of the Microtone Model T-612 "Fleetwood" hearing aid. The center compartment held a 1.4 volt mercury "A" battery such as the Mallory RM-12 battery, and the lower compartment held a "B" battery—probably a 22½ volt one such as the Mallory M-505 battery.
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Close-up view of the battery compartment of another Microtone Model T-612 "Fleetwood" hearing aid showing a label in the bottom of the "A" battery compartment. The label indicates this hearing aid used an RM-12 Mallory "A" battery.
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| View of the cover of the vacuum tube compartment of the Microtone Model T-612 "Fleetwood" hearing aid. It reads,"Microtone/Sealed Power/ T612/Four Tube Push Pull/St. Paul, Minnesota, U.S.A." The serial number (D-96992) is in blue (left) Note the slot in the left center of the cover. You inserted a small screwdriver to pry up the lid revealing the vacuum tubes (below). |  | Click picture for larger view | | | |
| View of the vacuum tube compartment of the Microtone Model T-6-12 "Fleetwood" hearing aid showing the two sets of paired vacuum tubes. These vacuum tubes worked in a push-pull configuration. The two larger vacuum tubes are Raytheon CK548DX models, and the two smaller tubes are Raytheon CX549DX models.
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| View of the front of the external microphone (bottom center) of the Microtone Model T-612 "Fleetwood" hearing aid. The external microphone had a chrome front and a cream plastic back. Above the microphone is a metal flower that could slide over it to disguise the microphone so supposedly people couldn't tell you were wearing a hearing aid. |  | Click picture for larger view | | | |
| Rear view of the external microphone showing the broach-type pin to fasten it to your clothing, and also showing how the disguising flower slides over the microphone (from the right). |  | Click picture for larger view | | | |
| Close-up view of the attractive metal flower showing how well it hid the external microphone. |  | Click picture for larger view | | | |
| Close-up view of the receiver used with the Microtone Model T-612 "Fleetwood" hearing aid. |  | Click picture for larger view | | | |
| The Microtone T-612 "Fleetwood" vacuum tube hearing aid in its original case. |  | Click picture for larger view | | | |
| Outside view of the Microtone T-612 "Fleetwood" case.
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