M-153/U Microphone, Voice Silencer

© Brooke Clarke, N6GCE

Ready to use
With Cover on
Mouth Piece

This is a special microphone designed to keep your voice from being heard by any one else when speaking.  There is a Push To Talk switch on top of the "nose".  The resulting sound is very crisp and easy to understand.  Operationally there is no provision for hearing so the VOL control on the radio needs to be turned almost to OFF so that the speaker will not make any noise.  To prevent warning tones the ANT switch should be on the correct letter for the frequency being used (maybe add some tape to the CHAN switch and the ANT switch.  Also be sure the battery is fully charged to prevent the low battery warning tone.

The manual mentions using the M-153, held to the ear, as a way to hear the radio output without others overhearing the audio, but I don't see how that is possible because as far as I can tell the M-153 is wired only to the A (gnd) and D (Mic) pins of the U-229 connector.  The MIC appears to always be connected to the A & D pins.  The PPT switch grounds the AUDIO "C" pin to A (gnd) when pressed.  The AUDIO "B" (ear) pin is not connected to anything.  The only way to use the M-153 as a silenced earphone would be to have the audio fed to it on AUDIO pin D, not too practical.

If headphones will be used with the M-153, then a Y cable will need to be used that allows both to be connected at the same time.

Side image showing the PTT switch on the "nose".  On the top of the rubber face gasket is the name "Stenomask".
Mouthpiece image showing the microphone element on the right.

Made by: Talk, Incorporated, 455 Union Ave., Westbury, New York 11590

The carry bag is marked: Bag, Microphone, CW-1037/U, FSN 5965-104-2901, MFR Code 96642
The DLIS CAGE code shows the following for 96642:


CAGE CODE: 96642
Status: A - Active

DUNS Number: 013373725

Voice Telephone: 516-616-1373

County: NASSAU

The Stenomask is a court reporters microphone that is the bases of the M-153.
NVRA - The Genesis of Stenomask Voice Writing by Horace Webb, HM
Photo of steno system from eBay


D427986 Dictation mask, Stephen D. Webb, Garn H. Webb, Andrew P. King (Talk Technologies Inc.), D14154 - this is just the design patent
D177947 DICTATION MASK, Henry A. Sherwood (The Sound Scriber Corp), Jun 5 1956, D14/225 ; D14/154 -
D236033 Tory Mack, Dryden, Jul 1975 - surgical breathing mask
D303440 Regulator mouthpiece, Steven M. Campbell (U.S. Divers Co), Sep 12, 1989 - scuba
D355484 Combination mask with breathing apparatus adaptor, Laney T. Rinehart, Feb 14, 1995 - surgical
2117236 DICTATING MACHINE, Bread (Dictaphone Corp), May 10 1938, 192/99S ; 369/260; D14/154 - accoustic tube to cylinder, no recording electronics
2526177 MASK FOR EXCLUDING AMBIENT SOUNDS, Horace ;L. Webb (Dictavox Co), Oct 17 1950, 181/242 ; 181/21; 381/354 - cone with head strap & handle
2572547 DICTATION MASK WITH CARTRIDGE TYPE SILENCER, Horace L. Webb, Oct 23 1951, 181/242 - sound deadening stuffing
2625615 SILENT DICTATION MASK, Horace L. Webb  (Dictavox Co), Jan 13 1953, 181/242 - alternate stuffing schemes
2857013 Dictation Device, L, Orso, Oct 21 1958, 181/242 ; 381/344- hand held sound deadening to either side
3193624 DICTATION MASK SOUND RECEIVER , H.L. Webb H.M. Steinman, Jul 6 1965, 381/382 ; 128/207.12; 381/376 -
This has the look of the M-153
2526177 see above
2572547 see above
2625615 see above
2830135 Dictation Type Mask with Valve Controlled Inhalation and Exhalation, Horace L. Webb, Apr 8 1958, 381/367 ; 181/242; 381/344
2848565 Sound Proof Mask for Hand Microphone, Horace L. Webb, Aug 19, 1958, 181/242 -

2390488 Noise Shield for Acoustic Devices, Alford (Bell Labs), Dec 11 1945, 181/242 - seperate noise and mouth funnels
2745911Ambietn Sound Excluding Dictation Mask, Horace L. Webb, May 15 1956, 181/242 -
2754377 Device for Prevention of Overhearing of Telephone Conversations, H. JUNGHANS, Jul 10, 1956, 379/439 ; 379/440; 379/447 -
attachment for mouthpiece of handset
2769040 Microphone Housing, A.L. Di Mattia (Dictaphone Corp), Oct 30 1956, 381/355 ; 381/354 - hand held
2830135 see above
2857013 see above
2974665 Gas Mask Speech Transmission, A. V. MOTSINGER, Mar 14 1961, 128/201.19 ; 128/207.11; 181/21; 367/132; 381/356; 381/376 -
3796842 DICTATION MASK, Eric L. Guille, Mar 12 1974. 381/367 ; 181/242; 381/344 - handle
4129754 Reporting device, Thomas A. Gore, Dec 12, 1978, 179/188; 181/242 - long snout tube with mike at end

3796842 Dictation Mask, Eric L Guille, Mar 1974, 381/367 ; 181/242; 381/344 - half shpere with handle

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