Sound Powered Telephone


© Brooke Clarke 2017 - 2021
Background
    In-Ear-Monitor
Description
    Element
    Remco Toy Sound Powered Telephone
    Wheeler Insulated Wire Handset
    Control Instrument Co. Handset
    Chest Set
    H-203 Handset
    TP-3 Sound Powered Telephone Set
    TA-1 Field Phones
    Baldwin Speaker Driver
        Baldwin Driver + Horn
        Baldwin Headphones
    Western Electric No. 555 Receiver
    Western Electric 509w Receiver
    Peerless Speaker (Lektophone)
   
Tivoli Audio Model One Radio   
   
CCRadio2
    Acoustic Research Speakers
   
A7 Voice of the Theater Speakers
   
Freed-Eismann Radio Speaker FE-50
Patents
    Electric Phonograph Pickup Patent 1921
    Murdock Headphones
    Exponential Folded Horn
    Sound Powered Elements
    Murdock Headphones
    Brandes Inc
    Henry C Harrison
    Condenser Microphone
    Throat Microphone
    Roanwell
        Photos
    Brush Development Co
Related
References
Links

Background

The Wiki page for Sound Powered Telephones has a number of examples of their use and mentions the USCG regulation that mandates their use on some ships.  The idea is to have an intercommunication system that will work without external power.  This usually is done for reliability rather than cost savings.  The TA-1/PT military field phone is sound powered.  The United States Instrument Corp. set consists of a chest mounted microphone and a pair of headphones.  It as a Jones type connector with 2 male pins.  Not sure of the application.
Dynalec still makes sound powered phones.

In military situations where there is a very high level of background noise, the microphones need to have good noise cancellation properties.  This needs to be combined with the sound powered aspect for a workable sound powered telephone system for military applications.  Note there are no switches which may be in the wrong position in a life threating emergency, i.e. this set is always going to work without any training.

While the telephone that A.G. Bell patented in 1876 used what today we call a dynamic microphone that outputs a voltage (i.e. in a way you could say sound powered) it was replaced in 1889 by the Edison carbon granule microphone that had much higher conversion gain, but required external DC power.

The efficiency of sound powered speakers is much higher than conventional speakers.  Here's the top of page 8 from the Instruction book for the H-203 handset (1938):
Sensivity of Sound Powered Speakers
                      (earphone)
Notice that the carbon mike has an output that's 25 to 33 dB higher than that of a sound powered mike.

Also, the speaker in sound powered phones is 10 to 20 dB more sensitive than conventional speakers.

In-Ear-Monitor (Wiki)

Balanced Armature (Wiki) headphones/ In-Ear-Monitors are very efficient.  The diaphragm is not stressed like with conventional headphones where a permanent magnet is pulling it.  The professional IEM offer excellent fidelity along with sound isolation.  These are typically custom molded to fit an individual ear & high $$$$$.  Used by professional musicians.
Balanced
                    Armature Driver
JH Audio: What is a Balanced Armature Driver, Part 2 The Guts and The Glory, The Siren Series: Layla (12 drivers per side)
7194103B In-ear monitor with hybrid diaphragm and armature design, Jerry J. Harvey, Filed: 2005-01-12, Pub: 2007-03-20 - both diaphragm and balanced drivers
8897463 Dual high frequency driver canalphone system, Jerry J. Harvey, JERRY HARVEY AUDIO HOLDING LLC, 2004-11-25 - Laya
8925674 Phase correcting canalphone system and method, Jerry J. Harvey, JERRY HARVEY AUDIO HOLDING LLC, 2015-01-06 - FreqPhase - a similar idea to the Altic Lansing Voice of the Theater speaker where the voice coils of the 15" woofer and the horn driver are in the same vertical plane to prevent sound cancellation/distortion at the 500 Hz crossover frequency.

US20140205131A1 Multi-driver earbud, Apple Inc, 2015-06-09 - in ear uses woofer, midrange and tweeter drivers Some In Ear Monitors (Wiki IEM) use a dozen or more drivers to get high fidelity sound (See JH Audio above)..

Description

The sound from the speaker's voice powers the phone so no external power is needed.

Sound Powered Element

United States Instrument Corp. 1247A G4 Sound Powered Element.  Measures 60 Ohms and makes sound when tested using the Fluke DMM DIODE test function (i.e. 1 mA)

Fig 1 Element sitting in cup (no cover)
United
                      States Instrument Corp. 1247A G4 Sound Powered
                      Element
Fig 2 After lifting the element out of the cup.
U.S. Instrument Corp.
UA1614-11
U.S. Patent
No. 2245511
United
                      States Instrument Corp. 1247A G4 Sound Powered
                      Element
Fig 3
After removing 2 screws to open back cover
United
                      States Instrument Corp. 1247A G4 Sound Powered
                      Element
2060607
                      Telephone, Joseph A Briggs, RCA, 1936-11-10

2060607 Telephone, Joseph A Briggs, RCA, 1936-11-10, 381/411; 381/418 -
electromagnetic type that is rugged and capable of withstanding severe shocks and blows
The Baldwin design was much harder to make and not as rugged as this one.
2100500
                      Telephone unit, Albert E Woodruff, Sengebusch
                      Hans, Associated Electric Lab, 1937-11-30

2100500 Telephone unit, Albert E Woodruff, Sengebusch Hans, Associated Electric Lab, 1937-11-30, -

Albert Woodruff worked for Associated Electric Lab from 1934 till 1941 (Start of W.W II?)
then he started working for Automatic Electric (Wiki: AE) and his last patent with AE was 1953.
2241106 Sound
                      translating device, Albert E Woodruff, Associated
                      Electric Lab,1941-05-06

2241106 Sound translating device, Albert E Woodruff, Associated Electric Lab,1941-05-06, 335/231; 335/279; 335/281; 335/276 -
2241107 Sound
                      translating device, Albert E Woodruff, Associated
                      Electric Lab,1941-05-06

2241107 Sound translating device, Albert E Woodruff, Associated Electric Lab,1941-05-06, 381/418; 381/419 - horseshoe magnet

US2245511
                      Telephone instrument, Turnbull Jr Arthur, Warnke
                      Herbert R, Us Instr Corp, Filed: Dec 4, 1937, Pub:
                      Jun 10, 1941
US2245511
                      Telephone instrument, Turnbull Jr Arthur, Warnke
                      Herbert R, Us Instr Corp, Filed: Dec 4, 1937, Pub:
                      Jun 10, 1941
2245511 Telephone instrument, Jr Arthur Turnbull, Herbert R Warnke, United States Instrument Corp, filed: 1937-12-04, Pub: 1941-06-10, 381/418 -

2400281
                      Electromechanical signal translating apparatus,
                      Leslie J Anderson, RCA, filed: 1940-10-31, Pub:
                      1946-05-14

2400281 Electromechanical signal translating apparatus, Leslie J Anderson, RCA, filed: 1940-10-31, Pub: 1946-05-14, 381/346; 181/166; 381/417;

Remco Toy Sound Powered Telephone

This pair of toy sound powered phones was very reasonable on eBay.  The reason is that one of them has a very poor electrical connection and the other about 11 Ohms, but steady.
You can see from Fig 2 below that there's only one sound power element and it serves as both the microphone and speaker.  The problem was they uses a pressure connection between the external terminals and a pair of spring contacts.

After using a pencil eraser to clean the terminals and bending one of the springs out a little the phone halves were mated and the Ohm meter read a solid 11.7 Ohms.  A few drops of acrylic cement (maybe) will complete the repair.

Control Instrument Co patent 2109761 uses the same method of using a single transducer and a speaking tube so it can be used as both the transmitter and receiver.

Fig 1
Remco Toy Sound
                      Powered Telephone
Fig 2
Remco
                              Toy Sound Powered Telephone
Fig 3
Remco
                              Toy Sound Powered Telephone




US2536179

US2536179 Magnetic sound-powered telephonic unit, Isaac Heller, Remco Ind, Jan 2, 1951, 381/161, 381/418, 381/396   

The bottom two illustrations are of how they make a long bar magnet and break it into small pieces for use in the element.
2692918
                      Magnetic sound powered telephone, Samuel I Berger,
                      1954-10-26
2692918 Magnetic sound powered telephone, Samuel I Berger, 1954-10-26, 381/418 -
Put this patent under the Toy phone because Berger has other patents for sheet metal toys.
Calls:
2245511 see above
2400281 see above
2454425 Magnetic translating device, Benjamin B Bauer, Shure Inc, filed: 1943-12-23, Pub: 1948-11-23, 335/231; 335/281; 310/25; 369/148 - dynamic mike
2523775 see below
2536179 see above
2582942 see below

Wheeler Insulated Wire Handset

AKA: Sound Powered Communications Corp.
SPT-125 with 1/4" Phone Plug

Fig 1 New Old Stock (NOS) SPT-125
Wheeler
                      Insulated Wire Handset SPT-125 with 1/4"
                      Phone Plug
Fig 2
Wheeler
                      Insulated Wire Handset SPT-125 with 1/4"
                      Phone Plug
Fig 3 Notice the same element for both talking and listening.
Wheeler
                      Insulated Wire Handset SPT-125 with 1/4"
                      Phone Plug

Wheeler Insulated Wire Co. adapted that name in 1922 since their main product was insulated magnet wire.  During the second world war they made the  ‘Marine ‘Raider’ Receiver.  (let me know what it is).  Only after the war did they start making sound powered phones. (Connecticut Mills).

Electronics magazine, Dec. 1949 - pg 179 Wheeler Insulated Wire Co. ad for transformers and other products that are mostly magnet wire, but no sound powered phones.

Fig 1



2492056 Batteryless ringing device, William J Muldoon, Wheeler Insulated Wire, 1949-12-20, 379/373.01; 340/328; 310/25; 381/162; 381/418 - dial plucks reed which is coupled to similar reed in Rx set.  Vibrating reed taps bell.  Intended for toy phones as well as short range general  applications

2523775 Electromagnetic transducer, William J Muldoon, Wheeler Insulated Wire, 1950-09-26, 381/418; 310/25 -

2523769 Calling unit, John H Maloney, Randall B Baker, Wheeler Insulated Wire, 1950-09-26, 310/25; 340/333- causes loud noise in receiver units rather than separate sound maker

2533136 Vibratory reed signaling device, William J Muldoon, Wheeler Insulated Wire, 1950-12-05, 340/384.73; 310/25; 116/167; 379/167.01; 335/93- more powerful ringing than patent 2492056

2582942 Electroacoustical transducer, Randall B Baker, Wheeler Insulated Wire, 1952-01-22, 310/25 - same application as 2523775.

2607857 Telephone handset, Randall B Baker, Wheeler Insulated Wire, 1952-08-19, 379/433.01; 446/142 - Tx and Rx units plug in (no screws), toothed wheel for 2523769 signaling

2634378 Vibratory reed signaling device, William J Muldoon, Wheeler Insulated Wire, 1953-04-07, 310/29; 340/6.13; 335/252; 335/230; 340/333 - even more powerful, includes bell

2808461 Handset, Aldrich R Thomas, Wheeler Insulated Wire, 1957-10-01, 379/422; 379/395; 379/433.06; 379/433.01- includes a PNP transistor amplifier in the Tx cavity or can work as sound powered w/PB switch.

Control Instrument Co. Handset

Fig 1 Type L
Serial No. 2267
N.D. Control No. d1515, N.D. Insp.
Intermittent connection.
Control Instrument Co. Handset Type L

Fig 2 inside both elements look the same.
Control
                      Instrument Co. Handset Type L

2109761
                      Telephonic device, Herbert R Warnke, Control
                      Instrument Co, 1938-03-01

2109761 Telephonic device, Herbert R Warnke, Control Instrument Co, 1938-03-01, -

The Remco toy uses the same method of using a single transducer and a speaking tube so it can be used as both the transmitter and receiver.

2115795 Magnetic unit, Herbert R Warnke, Control Instrument Co,1938-05-03, - for high power loudspeaker?
2143097
                              Telephonic unit, Herbert R Warnke, Control
                              Instrument Co,1939-01-10
2143097
                              Telephonic unit, Herbert R Warnke, Control
                              Instrument Co,1939-01-10
2143097
                              Telephonic unit, Herbert R Warnke, Control
                              Instrument Co,1939-01-10 2143097
                              Telephonic unit, Herbert R Warnke, Control
                              Instrument Co,1939-01-10

2143097 Telephonic unit, Herbert R Warnke, Control Instrument Co,1939-01-10, -
"...capable of Operating as a receiving unit or as a transmitting unit...high efficiency."

2163161 Magnetic unit, Leslie H Wadsworth, Control Instrument Co,  1939-06-20, - "one-piece magnet casting" - sound powered element (either Tx or Rx).
2215782
                              Telephonic unit, Grenville B Ellis,
                              Control Instrument Co, 1940-09-24
2215782
                              Telephonic unit, Grenville B Ellis,
                              Control Instrument Co, 1940-09-24
2215782
                              Telephonic unit, Grenville B Ellis,
                              Control Instrument Co, 1940-09-24

2215782 Telephonic unit, Grenville B Ellis, Control Instrument Co, 1940-09-24, - Diminishes "blasting" like happens with gun fire nearby.

For more patents by G.B. Ellis see Radiosonde Batteries.

2358529 Telephone system, William J Muldoon, Harold T Stenhammer, Control Instrument Co, 1944-09-19, - much simplified based on stepping switches.

2372801 Selector switch, Harold T Stenhammer, Control Instrument Co, 1945-04-03, -

D140289 Casing for telephone units, William J. Muldoon, Filed: 1944-08-21, Pub: 1945-02-06, - wedge shape unit

2380560 Permanent magnet, Urquhart Noel, Control Instrument Co, Filed: 1942-06-11, W.W.II, Pub: 1945-07-31, - "...a protective coating is applied thereto to prevent corrosion and chipping under shock. .." "It is an object of the invention to completely cover a permanent magnet with a protective coating, while causing no impairment of its mag netic performance."

2381673 Electromagnetic device, Lehde Henry, Control Instrument Co, Filed: 1942-04-06 W.W.II, Pub: 1945-08-07, -sound powered element, either Tx or Rx. very rugged, easily assembled,

2389695 Impulse sender, Harold T Stenhammer, Control Instrument Co, 1945-11-27, - quiets down the clicking noise of a phone dial
2432424
                      Electromagnetic sound translating device, John J
                      Hyland, William J Muldoon, Control Instrument Co,
                      1947-12-09 2432424 Electromagnetic sound translating device, John J Hyland, William J Muldoon, Control Instrument Co, 1947-12-09, 381/418; 310/25 -
2523775
                      Electromagnetic transducer, William J Muldoon,
                      Weeler Insulated Wire, 1950-09-26
2523775 Electromagnetic transducer, William J Muldoon, Weeler Insulated Wire, 1950-09-26, -

Chest Set

This set has a strong similarity to the Dynalec UA1814-1 (702020-110) NSN: 5975-01-27, DTID: 3211A0128BH21 but this set has the chest mount microphone support and headphone headbands.

In the movie Submarine: Steel Boats - Iron Men (IMDB) about life on the USS Hyman G. Rickover (Wiki) what appear to be sound powered chest sets are used in many places.

Fig 1 United States Instrument Corp.
United States
                      Instrument Corp. Sound Powered Telephone with
                      chest microphone



H-203/U Handset

This is a handset with Push-To-Talk button.  With the button up the resistance between the 2 leads shows open, when the button is pressed the resistance is about 32 Ohms.   In DMM Diode Test mode when the button is pressed and the leads are brushed against the phone terminals you can hear scratching sounds from both the mike and earphone on the handset.

Switch Plate marked:
Sound Powered Handset Type H-203/U
Stock No. 1N5965-247-0727
Navy Dept. Bu. Ships
Stromberg-Carlson
Contract No. N001 26-69-G-2303
Serial No. (blank) Insp. (blank)
Receiver Marked:
1247-A
Alcoa  2
Transmitter Marked:
1247-A
Alcoa  1

There is a small difference in the elements used for the microphone and speaker, but the fundamental part numbers seem to be the same.

Fig 1 The screw on caps are made of brass, not plastic.
H-203/U Sound
                      Powered Handset
Fig 2
15 MF
200 VDC
H-203/U Sound
                      Powered Handset


1247A
Alcoa 2
UA1614-1
U.S. Patent
No. 2245511

9/67
1247-A
Alcoa 1
UA1614-1
U.S. Patent
No. 2245511

10/69





TP-3 Sound Powered Telephone Set

This is a telephone set, meaning that it has ringer capability in addition to the sound powered aspect.  It has the same functionality as the TA-1 Sound powered field phone set below.
This is a derivative of the EE-8 Field Telephone and uses the same outer case (either leather or canvas) and many other parts interchange.  The key difference is that the handset makes use of sound powered elements and so it does not need a battery.  The sound power elements are the same as in the H-203 handset.

There are a couple of blocking capacitors included in this set, one to keep DC out of the sound powered handset and another to keep DC away from the ringer coils/core.  When used with a common battery switchboard an off hook signal to the operator is possible by shorting the L1 and L2 terminals in an alternating pattern of 1 second short 1 second open.

Manuals

Instruction Book for Telephone TP-3-T1
December 5, 1938
Reprint July 15, 1940

TM11-2043
TO 16-40T-P3-5
Telephone
TP-3
War Department - 30 August 1944

Technical Data

The handsets measure 36 and 40 Ohms.  About the same as the H-203 above which makes sense since they both use the same elements.

Fig 1
TP-3 Sound Powered
                      Telephone Set
Fig 2 the right side plate is bent.
TP-3 Sound Powered
                      Telephone Set
 From Instruction Book.
This is the same mechanism
as 1767546 Fig 2 (below).
TP-3 Sound Powered
                      Telephone Set
Fig 3
TP-3 Sound Powered
                      Telephone Set

TA-1 Field Phones

Note the ear piece is much thinner on the TA-1 when compared to the The chest set, H-203 or TP-3 above.  That's so that the ear piece can be placed under a helmet.

Fig 1 with carry case
TA-1 Field Phone
                      w/case
Fig 2
TA-1 Field Phone

Sound powered field phones with generator driven buzzer, so no batteries or external power needed.  On separate web pages TA-1.
Earphone element: SM-D-189373
Microphone element: TA-Z21/PT

Baldwin Speaker Driver

The 957403 patent dated May 10, 1910 appears to the the oldest on this web page and is for an efficient sound powered microphone or earphone, but it's not a loud speaker, i.e. there's no large cone.  Note that the term "speaker" was used in this time frame to mean anything that made sound.  So, for example a telephone handset has a microphone and speaker.  For loud speakers see the Lektophone.

This earphone driver uses the efficient drive mechanism where the coil axis is at right angles to the disk center axis.
Markings shown in Fig 1:

Nathaniel Baldwin Incorporated
Salt Lake, Utah
Pat. May 10, 1910 - Oct 26, 1926
Nos. 957403 - 1604251

When I used a magnetic polarity tester to determine the polarity of the horseshoe magnet the tester did not respond, meaning that the magnet had lost it's charge.  To recharge it I used a stack of neodymium disk magnets to recharge the horseshoe magnet. (see: K&J Magnetics)

Both of the below patents show some support for the armature on the end opposite the diaphragm drive rod.  The newer patent also shows the pole pieces that look very similar to the photos, but the spring support on the end of the armature opposite the drive rod is missing from this example.
The end of the armature can be moved so is somehow floating.

I attempted to add modern 1/16" thick magnets to the poles of the existing horseshoe and pole pieces, but it didn't seem to offer much improvement over just using a modern magnet to recharge the horseshoe magnet.  Fig 3 & Fig 4 were marked with measurements to help selecting magnets.

https://patents.google.com/?q=H04R11%2f00&inventor=Baldwin&country=US&sort=old


905781 Telephone
                      Receiver, N. Baldwin, 1908-12-01
905781 Telephone Receiver, N. Baldwin, 1908-12-01, 381/418; 340/388.1; 335/231 -
957403
957403
                      Telephone-receiver, Nathaniel Baldwin, May 10,
                      1910, 381/418
957403 Telephone-receiver, Nathaniel Baldwin, May 10, 1910, 381/418 -


1127161
1127161
                      Head-band for telephone-receivers, Nathaniel
                      Baldwin, 1915-02-02
1127161 Head-band for telephone-receivers, Nathaniel Baldwin, 1915-02-02, 381/379; D14/205 -
1153593
1153593
                      Telephone-receiver, Nathaniel Baldwin, Sep 14,
                      1915
1153593 Telephone-receiver, Nathaniel Baldwin, Sep 14, 1915, 381/418   
1581155
                      Sound-producing device of the telephone-receiver
                      type, Baldwin Nathaniel, App: 1922-06-14
1581155 Sound-producing device of the telephone-receiver type, Baldwin Nathaniel, App: 1922-06-14, Pub: 1926-04-20, 381/386 -
1592172
                      Telephone receiver, Baldwin Nathaniel, 1926-07-13
1592172 Telephone receiver, Baldwin Nathaniel, 1926-07-13, 381/418; 335/270 -
1604251
1604251
                      Telephone receiver, Nathaniel Baldwin, Oct 26,
                      1926, 381/418, 381/419
1604251 Telephone receiver, Nathaniel Baldwin, Oct 26, 1926, 381/418, 381/419 -

3: horseshoe magnet
4 & 5:
pole pieces
9: flat plate armature

RE16887
                      Telephone Receiver, N. Baldwin, App: 1924-12-05
RE16887 Telephone Receiver, N. Baldwin, App: 1924-12-05, Pub: 1928-02-21,  381/418 -

This is a Re-Issue of 1604251.

1683945
                      Telephone receiver, Baldwin Nathaniel, 1928-09-11
1683945 Telephone receiver, Baldwin Nathaniel, 1928-09-11, 381/418 -
based on patent 957403.
"... to provide a virtual fulcrum for the armature within the spool."
1683946 Loud
                      speaker, Baldwin Nathaniel, 1928-09-11
1683946 Loud speaker, Baldwin Nathaniel, 1928-09-11, 381/162; 381/165; 381/417 -

Paper cone diaphragm (4).


Hydrogen gas enters at port (7) , and flap valve (8 & 9) maintain a constant pressure inside the cabinet.
 
Fig 1
Baldwin
                      Speaker Driver
Fig 2
Baldwin
                      Speaker Driver
Fig 3
Baldwin
                      Speaker Driver
Fig 4
Baldwin
                      Speaker Driver

Baldwin Driver + Horn

This is a three part horn. 
The cast iron base holds the driver.
The cast iron neck connects the base to the big horn.
The big horn is made of Bakalite with a sheet metal ring for the connection to the neck

Fig 1
Baldwin
                      Driver + Horn
Fig 2 Note bottom plate of base is friction fit with felt trapped between the two.
Baldwin
                      Driver + Horn
Fig 3 Using the DMM Diode test function produces a loud scratching noise.
x
Fig 4 Nathaniel Baldwin Incorporated
Salt Lake City, Utah
Patented
May 10, 1910   Sept 14 1915
Those are different than the patents listed on the driver above.
They are 957403 and 1153593
x
Fig 5
x
Fig 6 "Standard Loud Speaker"
x

Baldwin Headphones

Label on back of phones:
Manufactured and Sold by the Baldwin Radio Co. Salt Lake City, Utah, under Nathanel Baldwin's Pat May 18, 1910 (see 957403 above), Sept 14, 1915 (see 1153593 above), Type "C".

Note that patent 1604251 (See above) is not referenced so these were made after 1915 and before 1924.

Fig 1
Baldwin
                      Headphones
Fig 1cu Close Up of Label
Baldwin Headphones
Fig 2 Pat Feb 2, 1915 (see 1127161 above)
Baldwin
                      Headphones
Fig 3 Inside
Baldwin
                      Headphones
Fig 4 Inside
Baldwin
                      Headphones


Western Electric No. 555 Receiver

This was the first loudspeaker to be used for talking movies (Wiki).  It consisted of the WE No. 555 moving coil driver coupled with a huge horn to make enough sound for to fill a movie theater.

1707544 Electrodynamic device, Albert L Thuras, Western Electric, Filed: 1926-08-04, Pub: 1929-04-02 - Dynamic moving coil speaker driver - WE No. 555
1729806 Electrodynamic device, Albert L Thuras, Western Electric, Filed:1928-04-26, Pub: 1929-10-01 - increase the efiiciency of electrodynamic devices
1812389 Acoustic device, Edward C Wente, Western Electric, Filed: 1925-04-01, Pub: 1931-06-30 - probably the No. 555 driver "Receiver"

Western Electric No. 509w Receiver

Patent date July 23, 1918
1273351 Telephone-receiver, Halsey A Frederick, WE, 1918-07-23, - maximum efficiency (for the time), uses Silicon steel coil core.

Peerless Speaker (Lektophone)

This speaker was made under the Lektophone Patents as were many early speakers while the patents were in force. 

The label spells this out.

Peerless
Licensed Under
Lektophone Patents
No. 1271527 - No. 1271529
No. 1271528 - Other Patents Pend.
Manufactured by United Radio Corp. Rochester, N.Y. U.S.A.

This speaker was purchased and it's located on the Sound Powered Telephone web page because the central axis of the coil is a right angles to the central axis of the speaker cone, i.e. an efficient structure.

The speaker measures 1.34 k Ohms.  There is a low pass filter made up of two capacitors and an iron core inductor between the input wires and the speaker proper.  When you look into the front with a flashlight you can see a second cone.  That's to say there are two speaker cones with different cone angles.

Photos

Fig 1 Front
Peerless
                      Speaker Mfg. by United Radio Corp. under
                      Lektophone Patents
Fig 2 Back
Peerless
                      Speaker Mfg. by United Radio Corp. under
                      Lektophone Patents
Fig 3 Bottom
Peerless
                      Speaker Mfg. by United Radio Corp. under
                      Lektophone Patents
Fig 4
Peerless
                      Speaker Mfg. by United Radio Corp. under
                      Lektophone Patents
Fig 5
Peerless
                      Speaker Mfg. by United Radio Corp. under
                      Lektophone Patents
Fig 6 Coil at top of horseshoe magnet
has it's axis up and down.
Peerless
                      Speaker Mfg. by United Radio Corp. under
                      Lektophone Patents

Patents

---------------------------- Listed on Label ----------------------
1271527
Sound-regenerating machine, Marcus C Hopkins, Lektophone Corp, Jul 2, 1918, 369/80, 369/158 - This is a flat record player (not Edison cylinder, Wiki) and instead of using a horn speaker (Wiki)  it uses a large diameter cone that has a rod driving the center point. 
1271528
Sound-regenerating machine, Marcus C Hopkins, Lektophone Corp, Jul 2, 1918, 369/158, 369/170 - very similar to the ...527 patent.
1271529
Acoustic device, Marcus C Hopkins, Lektophone Corp, Jul 2, 1918, 181/164, 181/173, 181/171, 369/155, 381/432  

-------------------------- Other Patents Pend. ----------------------

1389632 Acoustic diaphragm, Davis William H, Joss Fredrick E, Lektophone Corp, Sep 6, 1921, 181/171 - Just the cone part of a speaker
1829355 Acoustic diaphragm, Houghton Vernon T, Lektophone Corp, Oct 27, 1931, 181/173 about folding the cone outer diameter surface to add compliance.  Modern speaker cones have "ripples" to to that. 


1855168 Loud speaker, Farrand Clair L, Lektophone Corp, Apr 19, 1932, 381/418, 381/432, 181/172 - can be used as either Microphone or speaker.  "'The principal object of this invention is to provide a loudspeaker of the above described general type in which the flexible support for the diaphragm is supplemented by a special flexible support for the armature, which will permit the armature to move freely in an axial direction but will hold the armature, or assist the flexible support for the cone in holding it, in the proper aligned position in the air gap. "  Coil axis is concentric with cone axis so not the high efficiency Sound Powered Telephone design.
  

Lektophone Corporation v. The Rola Company, 282 U.S. 168 (1930) (Supreme.justia, FindLaw)
"The contribution of Hopkins, if he made one, as held in several cases in the lower courts and abroad, was to combine abandoning the sound box, determining the size of the cone deemed by him most suitable to reproduce the sounds communicated to it by vibration, and tightly gripping and rigidly supporting the outer edge of the above-mentioned annular rim of the cone between two rings. A result claimed for the rigid support, although seemingly not thought of at the time, is to avoid interfering sounds, "blasting" and ratting, that were made when the edge of  the cone was loose."

Lektophone Corp. v. Western Electric Co., 20 F.2d 150, 154 July 12, 1927 - (LEagle)

"There is not to be found in the prior art a sounding board such as Hopkins designed and had patented as his invention, and it is not enough to defeat his patent to say that the elements of his claims are already found in the prior art in isolation or in other combinations."
963362 Apparatus for recording or reproducing sounds, Thomas A Edison, Jul 5, 1910, 369/165; 181/162; 181/173; 369/168 -flat pleated disk, not a cone
986477 Acoustical instrument, Louis Lumiere, Mar 14, 1911, 29/896.23; 369/160 - pleated cone

Lektophone Corp. v. Crosley Radio Corporation, 46 F.2d 126; (CaseText)

Lektophone Corp. v. .S. G. Brown, Ltd. (Wiki), Ch.Div., January 23, 1929 (academic)

Tivoli Audio Model One Radio

Tivoli Audio (Wiki) - "The Company was founded in Massachusetts in 2000 by legendary audio engineer Henry Kloss and entrepreneur Tom DeVesto, who noticed a gap in the consumer audio market for high-quality, well designed and affordable audio products. Their first product was the Model One, a simple to use mid-century modern designed table top radio with a high-performance tuner, receiving FM radio in congested urban locations, while maintaining the ability to pick out distant or low power stations."

While watching a number of streaming TV series set in Scandinavian countries a common small table radio shows up. I searched for it expecting it to come from Sweden or Denmark.  But it was designed in the U.S.A. and some legendary audio people were involved.

While the design was what attracted me in the first place there are other features that make this even more attractive.  The Auxiliary input senses when the 1/8" stereo plug is inserted and turns off the radio audio automatically.  This allows the box to be used as an amplified speaker.  See: Music Speakers.  In addition there is an option for "12 Volt DC" power, which has two advantages, first: allows radio to be used in an emergency powered from batteries or a cigarette lighter adapter and second: by using a small battery as a portable music speaker.

It came with only the AC line cord, so I purchased an FM antenna with a Type-F connector on eBay as well as some stick-on feet since the factory feet had fallen off.

While researching this model I found a number of fix-it YouTube videos about replacing the tuning capacitor.  Rather than do that I looked for a radio that had a manufacturing date sticker hoping that meant the radio was new enough not to need that repair.  So far that's the case.

Photos

Fig 1
Tivoli Audio
                      Model One Radio
Fig 2  The black circle is the end of a tube
that's part of the bass reflex loading design.
Tivoli Audio
                      Model One Radio
Fig 3 Connectors
Aux In: 1/8" stereo
DC In: 5.5mm x
Ant: The eBay "75 Ohm Indoor FM Dipole Antenna Radio Stereo Signal Receiver Amplifier Aerial" is defective.  Instead of a wire center conductor it has a tube so will not fit.  I have a message to the seller: lepo-beauty.  More after I hear back.
This is a "PAL" connector for Eurpoe, not the wire type for the US.
Tivoli Audio
                      Model One Radio

Bass Reflex Speaker Design (Audio Judgement)

CCRadio2

This radio is made at C Crane located a few hours drive North of me.  It has bands: FM, AM, 2 meter Ham, WX & Aux audio in.  It does not have shortwave.
Runs on AC line or internal 6 D cell batteries.  This is much more convenient than using an external battery pack with the Tivoli above.  After a month or so the "D" batteries have gone dead.  Not sure if that's because they started out low or if the radio consumes a lot of power when "off".  You should probably store batteries out of the radio.
When the batteries die so do all the presets.

Not so great as an emergency radio because there will be no preset frequencies.  You need a hard copy so you can load the frequencies after  you install fresh batteries.
There are 5 preset frequencies for each band so a total of 20.  To select a preset you need to first choose the band then press the desired preset.

There have been a number of CCRadios with different features over the years.  Got this one used from eBay.  It's the CCRadio2 not the CCRadio2E that has better sound quality.
Preset frequencies:
1. (2 meters) 147.39

Press and hold a control for a few seconds to get the (secondary function).
Main Tuning knob (Squelch)

Unlike the Tivoli above, this radio does not have an external FM antenna input.

Power

AC mains or internal 4 internal D cell batteries.

Mode
VDC
Function
Current
ma
Off
6.0
BL Off
0.001
Off
6.0
BL Very Dim
0.000
Off
6.0
BL Bright
0.017
On
6.0
Loud
0.3
Dead 3.9 -- --

The Energizer L95 (datasheet.pdf) should last a very long time IF the Back Light (BL) is off or very dim AND the WX monitor function is turned off.
Note: When the battery goes dead you loose all preset frequencies.

Fig 1 Front
CCRadio 2
                      Radio
Fig 4 Close-up of top Push Button PCB.
Right Angle Momentary Tactile Push Button Switch
maybe 6x6x5mm size?
The buttons are hinged and
have a post that presses on the switch.
There are Surface Mount resistors, maybe the resistance
indicates which button pressed, or it's a matrix?
CCRadio 2
                      Radio
Fig 2 Rear
CCRadio 2
                      Radio

Fig 3 Inside - Looks like was in dusty environment.

CCRadio 2
                      Radio
Remove 6 screws (all have an arrow).
Top: Ferrite Antenna
8 Push button PCB
Left: RF & AF PCB..
Left hidden: Front panel PCB
Middle: 4 Ohm 6 Watt Speaker
AC to 6VDC power supply at lower right corner.

Acoustic Research Speakers

Acoustic Research (Wiki) - "Acoustic Research, Inc. (“AR”) was founded in 1952[1] and incorporated on August 10, 1954, by audio pioneer, writer, inventor, researcher and audio-electronics teacher Edgar Villchur and his student, Henry Kloss."

When I built a Heathkit Hi-Fi system the speakers were copies of the AR-1.

YouTube: DeVORE FIDELITY: John DeVore goes on a rant about the High End Audio lie that inspired him to start his company - This is about speaker sensitivity: 

2775309 Sound
                        translating devices, Edgar M Villchur, ACOUSTIC
                        RES, 1956-12-25


2775309 Sound translating devices, Edgar M Villchur, ACOUSTIC RES, 1956-12-25, 381/346; 181/151 -

A7 Voice of the Theater Speakers

Altec Lansing (Wiki), JBL (Wiki)
I got these as part of a Hi-Fi system that was built into a house.  There were alcoves on either side of the fireplace where these sat.  A speaker cloth grill covered them and the wiring was routed inside the house to the electronics which ended up being McIntosh.  See Home Theater VOT for more.

The sensitivity of the A7 VOT is 97 dB. (sound level 1 meter in front of speaker with 1 Watt drive.)  This goes directly to dynamic range since the maximum power is limited to the 200 Watt speaker rating or the amplifier rating.  When music is played loud you're at the max rating for the loud passages and the speaker sensitivity for the quieter passages.

The heart of the speaker is the horn (Wiki).

A comment by James Wilkes related by my comment on the YouTube:

YouTube: DeVORE FIDELITY: John DeVore goes on a rant about the High End Audio lie that inspired him to start his company - This is about speaker sensitivity: 
Looks like they have a 515B LF driver, Altec Lansing specs for it say 98dB at 4' with 1W pink noise 500-1000 Hz, which is probably the safe figure -
500-3000 Hz yields 102 dB, but that's because the driver is rather peaky above 1000 Hz. SPL varies with distance per square law,
so a reading from 1m should be nearly 2 dB higher, approaching 100 dB/1W/1m. Very efficient speaker.

Time Alignment (Wiki)

This may be the reason that the voice coils of the horn and speaker are in the same vertical plane.  Another reason may be to make the horizontal pattern the same for the horn and speaker.  Both of these would tend to make the sound better over a larger area than not doing it.

The web page on time alignment (http://www.troelsgravesen.dk/Time-Alignment.htm) shows a case where the frequency range is about 1600 to 4000 Hz and so may not be applicable to the VOT speaker where the crossover frequency is around 900 Hz and where the physical difference is voice coil locations would differ by almost two feet.

A7
                    Voice of the Theater Speakers

1707545
                      Acoustic device, Edward C Wente, Bell Labs,
                      1929-04-02, 181/159 - Horn speaker/microphone
1707545 Acoustic device, Edward C Wente, Bell Labs, 1929-04-02, 181/159 - Horn speaker/microphone
1812389
                      Acoustic device, Edward C Wente, Western Electric,
                      1931-06-30, 381/346 - direct-radiator loudspeaker
1812389 Acoustic device, Edward C Wente, Western Electric, 1931-06-30, 381/346 - direct-radiator loudspeaker
1992268
                      Acoustic device, Edward C Wente, Bell Labs,
                      1935-02-26, 181/187 - sectional horn
1992268 Acoustic device, Edward C Wente, Bell Labs, 1935-02-26, 181/187 - sectional horn

Freed-Eismann Radio Speaker FE-50

See my Crystal Radio page for information on this exponential horn speaker.  Like the VOT above it's very efficient.

Patents

Electric Phonograph Pickup Patent

Prior to the early 1920s all the reproducers were mechanical in nature because vacuum tubes (Wiki) were not yet available.

1384295 Electric reproducer for phonographs, Pierre Frely Henry Armagnat An (Paris, France), Jul 12, 1921, 369/148 - prior to this all pickups and reproducers were mechanical.
1531252 Electrical reproducer for phonograph records, Thomas Jones Edward, Wired Radio Inc, Mar 24, 1925, 369/147 - electrical pickup, 2 tube amp, driver & Horn.  Spring motor for phonograph disk.
1536116 Sound reproducer, Martin William H, American Telephone & Telegraph, May 5, 1925, 381/184, 381/432 -  Fig 2 efficient design driving diaphragm attached to cone, horseshoe magnet
1596045 Sound reproducer, Frank J Kaehni, William L Kaehni, Cleveland Trust Co, Aug 17, 1926, 369/9, 123/73.00V - driver moves flat diaphragm attached to dish shaped cone, i.e. driving the wrong part.
1734271 Conical-diaphragm sound reproducer, Peterson Charles W, Nov 5, 1929, 181/166 -

Exponential Folded Horn

2338262 Acoustic horn, Vincent Salmon, Jensen Radio Mfg Company, Jan 4, 1944, 181/192, 181/194 cited by 4176731 Altec Corp. dual exponential horn. See Voice of the Theater)

Sound Powered Elements

All of the below patents use the same type of element where a rod couples the diaphragm to the permanent magnet device.

1767546
                      Sound-reproducing device, Mueller Herman C, Jun
                      24, 1930



1767546 Sound-reproducing device, Mueller Herman C, Jun 24, 1930, 381/418, 381/419 - this is a loudspeaker consisting of an exponential horn connected to a removable "driver".  The driver contains a horseshoe magnet. 

This is very similar in function to the
Freed-Eismann Radio Speaker FE-50 and the Baldwin + Horn above.  These speakers needed to be very efficient since they were powered from crystal radios with very low output power.  Note that a speaker of this type can also be used as a microphone.

This patent is cited as prior art by the Roanwell patent 3454912 below.
1886031 Mechanical construction of loud speakers, Langley Ralph HCrosley Radio Corp, Nov 1, 1932, 335/231, 335/281, 335/266, 335/270 -   
2267808 Electromagnetic device, Nelson Blount, Bell Telephone Labor Inc, Dec 30, 1941, 335/231, 381/354 - ..improve the efficiency and operating characteristics.... 

2391627
                      Transducer, Howell Arthur S, Stromberg Carlson Co,
                      Dec 25, 1945

2391627 Transducer, Howell Arthur S, Stromberg Carlson Co, Dec 25, 1945, 381/418 - "A telephone of this type is adapted to serve either as a transmitter or receiver thus when two of such, telephones have their respective terminals connected by suitable conductors in an electrical circuit, the arrangement comprises a complete telephone system which operates without an external source of current or power other than the sound from the speakers voice. Such a soundpowered telephone is especially useful for military purposes and therefore it must be small in size so that it can be used in conjunction with a helmet and its construction must be such that it will not bedamaged when overloaded by loud blasts."




2603724
Sound translating device arranged to eliminate extraneous sound, Kettler Alfred H, Rca Corp, Filed: Oct 30, 1948, Pub: Jul 15, 1952, 381/372, 381/359, 181/129, D14/249 - a noise cancelling headsest.  Needed because headphones act as microphones when not on a head.  They add noise into a multistation sound powered phone system.  Switches are not good in a emergency situation. 
2611035 Noise-canceling microphone, Duncan Robert K, Rca Corp, Sep 16, 1952, 381/94.9, 381/170, 381/115, 381/91, 381/94.7 - two microphones back to back "noise-cancelling close-talking"
2714134
Headset receiver, Kettler Alfred H, Touger Martin L, Secretary of the Air Force, Filed: Feb 27, 1951, Pub: Jul 26, 1955, 381/345, 381/371 - designed to work from sea level to 40,000 feet. 
2896026 Sound
                      powered phone, Kettler Alfred H, Secretary of the
                      Navy, Filed: Nov 2, 1953
2896026 Sound powered phone, Kettler Alfred H, Secretary of the Navy, Filed: Nov 2, 1953, Pub: Jul 21, 1959, 381/177, 381/337, 381/355 - This is about adding an effective noise cancelling capability to a sound powered phone for use on ships during wartime conditions.

2912523 Electro-acoustic transducer, Knowles Hugh S, Mullen Joseph EIndustrial Research Products Inc, Nov 10, 1959, 381/418, 335/301, 335/231, 335/252, 335/235, 310/25, 335/236 - for use in hearing aids as both mike and speaker.  Not susceptible to or cause external magnetic fields so the mike can be close to the speaker.  
3111563 Electro-mechanical transducer, Elmer V Carlson, Industrial Research Products Inc, Nov 19, 1963, 381/418, 335/231 - external magnetic flux changes have no effect on output, i.e. shielded.
3454912 Transducer drive rod, Morrison Louis A, Roanwell Corp, Jul 8, 1969, 335/231, 381/412, 381/396 - headband holds two receivers, adjustable height of each receiver

Murdock Headphones

These may not belong on the sound powered telephone web page, but I've found some patents and his is where I'm parking them.
 655726 Telephone-receiver, William J Murdock, 1900-08-14, 381/393 - long pole or headphone style
 786588 Telephone-receiver, William J Murdock, 1905-04-04, 379/428.01 - long pole
 801034 Telephone-receiver, William J Murdock, 1905-10-03, 379/440 - long pole
 853186 Telephone, William J Murdock, 1907-05-07, 379/428.01 - long pole case molded with woven core
1091528 Circuit-detector, William J Murdock, 1914-03-31, 324/555 - headset with series battery and test probes = audible continuity tester (test equipment, not phone)
1513924 Telephone head set, William J Murdock, 1924-11-04 - similar to 1583088 except pinch screw height adjustment
1583088 Telephone head set, William J Murdock, 1926-05-04 - headband & two earphones, spring clip earphone height adjustment

Brandes Inc

1447969 Telephone head set, Dietrich Frederick, Brandes Inc, 1923-03-13, 379/430; 296/139 - adjustable headband, see YouTube
1536482 Telephone receiver, Dietrich Frederick, Brandes Inc, 1925-05-05, 381/412 - matches design in YouTube video. - specifically mentions ability to take apart without breaking leads, but in video all the leads were broken.
1543325 Headband for telephone head sets,
Dietrich Frederick, Brandes Inc, 1925-06-23, 2/209.3; 381/376 - to fit head of wearer
1544136 Electrical connection for telephone headsets,
Dietrich Frederick, Brandes Inc, 1925-06-30,  381/379; 174/36; 381/189; 381/377 - not exposed terminals so B+ from tube radio will not cause electrical shock.
1645231 Electromagnetic sound reproducer, 
Dietrich Frederick, Brandes Inc, 1927-10-11, 381/160; 381/432 - triangular speaker enclosure
D71138 Loud Speaker,
Dietrich Frederick, Brandes Inc, Sep 28, 1926, D14/211 -

Patents by Henry C Harrison 

Condenser Microphone

 1333744 Telephone-transmitter, Edward C Wente, WE, 1920-03-16, -

Throat Microphone

I've read that these always sounded garbled and so were not used for very long.

2121778 Sound translating apparatus, Ballantine Stuart, 1938-06-28 -
2121779 Sound translating apparatus, Ballantine Stuart, 1938-06-28, - cited by 25 patents

2121780 Sound translating apparatus, Ballantine Stuart, 1938-06-28, -
2121781 Sound translating device,
Ballantine Stuart, 1938-06-28, -

Roanwell

This NT-51007A (NSN: 5965-665-3480) is NOT a sound powered unit, but rather a carbon microphone type.

Patents

Related to the 51007-A handset.  The 51007 has a carbon mike element.  A retrofit kit (Navy-Radio: Xmtr-handsetsNT-51007a) replaced the mike and speaker with new elements giving the 51007A a dynamic mike with built-in amplifier and circuitry that allows it to work with equipment that expects to see a carbon mike element.
Roanwell still makes the Type 503  H-169/U handset which is based on an upgrade kit to the 51007 replacing the carbon mike element with a dynamic element that contains an amplifier designed to run from the carbon mike DC bias.  This mick element is a noise cancelling design so your lips need to be touching the mouthpiece.  I think the speaker element was also replaced.  Newly made H-169/U handsets are gray in color.

Navy-Radio:  Transmitter Handsets -
51007A
Carbon Mike element: 35 - 50 [or 35 Ohms +/- 10] Ohms.  1300 Ohms DC!  Maybe the mike element is bad?
Speaker Impedance: 600 [or 600 Ohms +/- 150] Ohms. 143 Ohms DC. 370 Ohms @ 1 kHz

This appears to be a New Old Stock (NOS) handset.  The switch only has a single blue wire.

From NAVSEA 0967:

page 97:

STOCK NUMBERS FOR COMPONENT PARTS IN HANDSET H-169/U, FSN N5965-679-9501

Transistorized Type Handset H-169/U, complete with cord-assembly CX-1846A/U, is now available from stock, under FSN N5965-679-950l. This handset is used with equipments AN/URC-32 and AN/WRT-2. In many equipments, it can be used as a direct substitute for Handset Navy Type 51007A.

Component parts for Handset H-169/U are available from stock, under the following stock numbers:

Description
p/n
FSN
NSN
Handset H-169/U w/cord assy CX-1846/U
RC-10385/C 5965-679-950l
5965-665-3480
5965-00-679-9501
Handset H-169/U w/o cord assy RC-10385 N5965-803-438l
Earphone element RC-10379 N5965-678-5305
Microphone unit, w/retainer ring
RC-10367 N5965-678-5478
Microphone unit, w/o retainer ring RC-29020 N5965-624-4l34
Microphone retainer ring
8C-l5014 N5965-624-4l4l
Cord assembly CX-l846A/U N5965-803-438l

"SHOCK HAZARD ON HANDSETS H-169/U AND N.T. 51007A
It has been reported that a shock hazard exists on a few Navy handset types H-169/U and N. T. Sl007A. This is caused by a misalignment of the leaf of spring of the switch which shorts the push-to-talk button (metal) shaft and, in turn, places the keying potential on the plate of the switch . When the switch button is engaged or released , an inductive kick-back potential is present on the switch plate.  If a handset is considered to be a shock hazard, or if a continuity check indicates a short between the  switch plate and the plug pins, the handset should be modified as follows.
1. Re-align the pile-up of the push-to-talk switch in order to prevent shorting to the metal shaft.
2. Reverse the green and block leads of the switch, which removes the keying voltagee from the leaf spring which, in turn, shorts to the metal shaft. Figure l shows the modified wiring diagram of the handset switch.
3. Determine weather excess solder is causing the short.

The drawing for handset H-169/U has been modified in order that future procurement of the handsets will be manufactured to reflect this modification. The handset switch is available from stock under the Federal Stock Number: N5930-678-5304."

"H-169/U and H.T.-51007A; Modification of Handsets

It has been reported that the push-to-talk switch on some H-169/U and NT-51007A handsets bind and in some cases, break due to the guide pin coming in contact with the metallic rails directly under the switch .

It should be noted that the difficulty is not apparant  upon visual inspection, but develops while the handsets are in actual use. If, upon depressing the button at a slight angle, the switch short circuits to the two brass rails, the handset should be modified by machining the rails as indicated in figure l.

Specifications have been modified to prevent future procurement of handsets with the defects indicated above. (631)."

 page 98:
"H-169/U Handsets - Electromagnetic Interference in Shipboard Installations

Electromagnetic interference in the H-169/U handset was detected during a recent survey conducted on the DE-1052 class ships. Investigation has indicated that the H-169/U handset (containing an unshielded solid state audio amplifier within the microphone transmitter element) when physically located in open or semi-open areas, such as flying bridge, bridge wings or pilot house, are vulnerable to samples of reflected electromagnetic energy from the ship's radar. Due to the reflective characteristics of the ship's structure, sufficient levels of reflected RF energy are present in the pilot house to degrade radio communications. The signals are detected and amplified within the self contained solid state circuit of the H-169/U and reproduced as a series of audio pulses, representative of the pulse repetition frequency (PRF) of the offending radar.

The capability of the handsets (located in the exposed areas) for detecting the PRF of the radar can be prevented simply and inexpensively by replacing the existing dynamic' solid state amplifier transmitter element with a carbon element as used in the older Navy Type 51007A Handsets. This carbon element is in the supply system under FSN 9N5965- 586-0831. The dynamic and carbon elements are directly interchangeable, however, the carbon element will slightly degrade transmitted audio fidelity.

NAVSHIPS has taken direct action to accomplish this change to SCN funded ships of the DE-1052 class. Active Fleet ships (OPN funded) should requisition the carbon elements when similar electromagnetic interference problems are encountered. (803)"

Roanwell 51007A Photos

Fig 1
Roanwell
                      51007-A handset
Fig 2
Roanwell
                      51007-A handset
Fig 3 Speaker 10088
Roanwell
                      51007-A handset
Fig 4
Roanwell
                      51007-A handset
Fig 5 Mike element 10118 is from the NT-51007A (MIL-HDBK-173)
Roanwell
                      51007-A handset
Fig 6
Roanwell
                      51007-A handset
Fig 7 Mike Element 10118: no polarity marks.
The dynamic mike elements have (+) and (-) polarity marks next to the electrical terminals.
Roanwell
                      51007-A handset
Fig 8 Carbon Mike Element marked: Roanwell Corp. 13544 (A)
This has the look of a classic telephone carbon mike element.
Measures about 1500 Ohms, not 35 Ohms,
so probably needs help or replacement.
Roanwell
                      51007-A handset


Brush Development Co

2383832
                      Intercommunication system, Alfred L W Williams,
                      Brush Development Co, App: 1943-01-29, Pub:
                      1945-08-28
2383832 Intercommunication system, Alfred L W Williams, Brush Development Co, App: 1943-01-29, Pub: 1945-08-28, -

The microphone works by bending a piezo bar.  The call wheel works by bending this same bar.  The microphone also acts as the speaker by means of a speaking tube that connects the mike and speaker positions.

Brush Development Co made a lot of piezo crystal based products.

Related

Audio - military audio connectors
Aviation Headsets -
Bell System 302 Dial Phone - the "I Love Lucy" phone, this is the first phone I can remember.  The first phone to have all the parts in one case.
Bell System 500 Dial Phone - basis for the REN Ring Equivalence Number that's on the label of all modern phones
Bell system 2500 Touch Tone phone -
Beltone 12D Audiometer
CA-67 Interface Unit, Automatic Data Processing  Stardynamic  5895-01-443-5081
Cell Phones
DialTelegraph
EE-8 Telephone Set
E-89-A Telephone Repeater
EM200 EM200 Ear Mike
Fullerphones
GR650A General Radio GR 650-A & GR 1650B Impedance Bridges
GRsound General Radio Sound Measurement Instruments
GRA-39 Radio Set Remote over phone wire
H161 H-161E/U Headset used in Crew Served Vehicles (2 connectors)
H-207A/VRC Handset
H250 H-250/U Handset with Noise Canceling mike
H251 H-251A/U Headset (earphones)
H33 H-33F/PT Handset
H350 H-350/U Handset
Harris RF-5980-SA001 Amplified Speaker
Harris TS1000 ADSL Test Set -
Harris TSP-21 Telephone Test Set Plus (like but set, but belt-clip & operators headset
Home Theater - 7.1 Surround Sound - Voice Of The Theater Speakers (very efficient)
HP204 HP 204B Audio Oscillator from HP 3350 Carrier Test Set (AN/USM-181 Telephone Test Set
HP241A HP 241A Audio Oscillator w/Radio Buttons
HP415E HP 415E SWR Meter - 1 kHz tuned voltmeter
HP4260 HP 4260A Universal Bridge
HP 4261A LCR Meter
HP427A HP 427A Voltmeter AC & DC Volts & Ohms
HP4274_4275_LCR lHP 4274A & HP 4275A LCR Meters
HP4332 HP 4332 LCR Meter
HP 4395A HP 4395A Combination Network, Spectrum, Impedance Analyzer includes audio frequencies
HP33120 15 MHz Function/Arbitrary Waveform Generator
HS2B4 Plantronics Supra  -01NC 992C Headset
HS30A HS-30-A Headphones, CD-604 Transformer
HYX-65-1 Wire-line Adapter Local Unit & KY-65
KS-8455L2 Kick Test Set Line Loop Tester Telephone Installers & Repairman's Meter
KY68 KY-68 Secure Field Telephone
LS-147 Intercom
LS454 LS-454/U Loudspeaker
LS-685/U Crystal Loudspeaker
LS-688 PM Loudspeaker
M1024 Magnacord 1024 Reel to Reel Tape Recorder
M153 M-153/U Microphone, Voice Silencer
M80 M-80/U Handset (Microphone)
MAA Military Audio Accessories - tables with thumbnail photos & links to more info.
MATEL 2C800 Field Phone by Racal Acoustics Ltd.
MK-356/G Wire Splicing Kit
MRC67 MRC-67A Amplifier-Speaker
Music
No6 - No. 6 Dry Cell
Noisecom 7110-FAC Programmable Noise Generator
NSLB Model NS-LB Noise Generator
Panasonic KX-TA824 Telephone System
PatchP Audio Patch Panel
Racal MATEL 2C800 Field Phone
RS 38-A Carbon Microphone
RT1185 RT-1185/GRA-114 Sound Observer Receiver Transmitter
SB-22A Analog  Switchboard
SB-4170 Digital Switchboard
SB-3614A(V)/TT Telephone Switchboard
SG-886A/UR Interference (Noise & Tone) Generator
SidekickTandN Tempo Sidekick T&N Telephone Line Tester
Spying on Cell (Mobil) Phones
Subscriber Loop Analyzers
TA-1 Sound Powered Telephone Set
TA-1042  Digital Non-Secure Voice Terminal (DNVT)
TA-312/PT Telephone Set  (Field Phone)
TA-341/TT
TA-838/TT Telephone Set
Teledyne Avionics TA-3D Acoustic Impedance Meter - ear canal impedance
Telegraph Telegraph Equipment, Stock Ticker, District Telegraph, Teletype, Keys, Relays, Sounders, Veedre Counter, Early Connectors, Electro-magnets
Telephones
Telephone Patents & photos
Telephone Tool Kit
Telephone Poles - Utility, Power, Cable TV Poles
Tempo Sidekick T&N Line Tester
TF2700 Marconi TF-2700 Universal Bridge
TG-5-B Telegraph Set
Tone & Probe station wire testing
TS-2839/GY German H-33 Audio Test Set
TS-3647/G, Control Orderwire Unit (COU), Telephone Test Set
TS585 TS-585 Audio Level Meter
TSD-3600 Telephone Security Device
TSEC/KY-68 Digital Subscriber Voice Terminal
U229AA U-229 Audio Accessories
U229PO U-229 Pin Out by Function
U229Y "Y" Cable,  U-229/U
UIQ10 UIQ-10 Public Address Set
VIC VIC Vehicle Inter Communication & VRC-12 Series Radios
Voice Over Internet Protocol (VOIP) Phone Service
Western Electric 202 Dial phone- consists of a phone and a "sub set" that's mounted on the wall.
WE 500 Dial Phone -
Western Electric 2554 Wall Touch Tone Telephone
WTFME1 Funkanpaßgerät WT-FM-E1 AP01 Telefunken Military wire to radio interface
Xtal1800 Crystal Radio 1800? & Brooke Clarke #1 & horn speaker
ZM-4B/U Resistance Bridge
Zo Transmission Line Zo vs. Frequency - down to audio

References

History of the AES: Loudspeaker History -
IEEE: Bell, Watson, Soft Iron, and the Insight That Commercialized the Magneto Telephone, Ralph O. Meyer, V108, No. 12 -
Crystal Radio Net -
Sound Powered Phones for Crystal Radios - Impedance and Resistance Measurments Of Sound Powered Elements -
Submarine Telephone Talker's Manual, NAVPERS 16171 (subtalker.pdf), Dec 1944, by NDRC & Navy training (then Restricted) -
Circuits:
Circuit
Type
Function
Locations
XJA
Phone
General Communication
All compartments
JA
Phone
Torpedo-gyro control
Aft Torp, Maneuvering, Conning, Control, For Torp
1JP
Phone
Exterior circuit
Bridge to XJA-or-JA; Conning to Deck gun
7MC
Speaker Combat Information
Bridge, Conning & Control
1MC
Speaker Emergency & PA
all compartments
Numbers: WUN, TOO, THUR-REE, FO-WER, FI-YIV, SIX, SEVEN, ATE, NINER, ZE-RO

Links

PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale
Page Created  2017 October 13