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WE 500 Early Production Sets and Components

Comparison of 1948, 1949 and 1950 sets.

©2010-14 paulf.  All rights reserved.
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1949 Set   1949 dial   1949 housing   1949 ringer


Photos clearly demonstrating the differences among pre-production and early production 500 sets have been elusive.
This page displays photos of 1948, 49 and 50 -dated components submitted by collectors.

Based on documentation found to date, sets are grouped as follows:

Pre-production sets -- made in 1948 or earlier.
Early Production sets -- made before October 1949, some used in the 1949 field trial.
Production sets -- made in October 1949 and later. Photos of a 1950 set are used on this page.

So far, we have photos of only one pre-production set and have info on only a few 1949 sets.
There are probably more variations that were made that are yet to be discovered.

This page is a work in progress.  Please send comments, additions and corrections.

Photos: D177001 by Dan Robinson, early 1949 set in the Museum of Communications (Seattle) by Greg Goebel.

Last update: 13 October, 2014

Pre-production set
(Photo from Pacific Tel Magazine, May/June 1949.)
1948  Pre-production set.

     Marked D-117001, undated.

(Best guess based on research to date.  Watch for updates.)

Internal components similar to the patent drawings.

Aluminum dial mount. Plastic fingerwheel.
Bell coil wrapped in olive cloth (like 302s B1A).

Aiming dots, visible through the fingerwheel holes, were added during the development process to help improve dialing speed and accuracy.

Field Trial of 50 pre-production sets.  (BSTJ*, 4/51)

*Bell System Technical Journal
Early production 500 set, 1949
1949, Early production set.

    No model number marked, dated on front edge of bottom plate.

Internal components were modified to satisfy manufacturing and service considerations.  Metal fingerwheel.

Field Trial of 4000 early production sets in 10 locations, including Manhattan, Staten Island, Chicago, St. Paul, St., New Orleans, Los Angeles and San Francisco.  (BSTJ, 4/51)  Also St. Louis. (From an internal Bell System memo in the AT&T Archives)
Points of Comparison
between Pre-Production and Production Sets
Points of Comparison

These features shown on the patent drawing were changed before the "early production" sets were made:

1) Hook switch and dust cover shape.
2) Horizontal hook switch lever shape.
3) Screwed on Feet.
4) Dial component layout and cover shape.
5) Overhanging network cover.
6) Base plate stamping shape and features.
7) Ringer mounted with 1 screw, supported by 2 rubber grommets in base plate.
8) Large nut visible on equalizer case.
9) Plastic fingerwheel (not metal).

Note: It may help to open this drawing in a seperate window for reference while you scroll through the following photos.

Component Markings


D-117001 Set

Production Set

Base plate

D-117001 125



D-177006 124  



D-177008 132  



D-177018  35  


Switch hook




W35148   209  


*Component serial numbers for detailed tracking and control were eliminated on production sets.

1948 Base (D177001 - Pre-production)
D177001 base
1949 Base (Early Production)
1949 base

1950 Base (Production)
1950 base
Cutouts in dial mount are to hold terminal strips for optional future features.
Similar slots in the hookswitch mount are for an exclusion switch mount.
These greatly increase the flexibility of the set, reducing inventory and making it possible
to easily convert from one model to another during refurb.

Bottom Plate
1948 Bottom (D177001 - Pre-production)
D177001 bottom
1949 Bottom (Early Production)
Drilled for mounting future options: tube for party line ringing, and line switch for 2-line version.
Rivited feet.
1949 bottom

1950 Bottom (Production)
1950 bottom
Model number added and date format simplified.

1948 D-177008 Dial (D177001 set - Pre-production)
Dial with cover    Dial with inspection window
Included an inspection "window" on the front to watch the gear in motion.  Eliminated before production.

D177001 dial    D177001 dial, recreated fingerwheel

1949 (Early Production) and 1950 (Production) 7A Dials were the same,
including the "Operator" text circling the 0 digit on the dial plate.

7A dial, back, October 1949    7A dial, October 1949
Dial components were rearranged, probably to make the footprint small enough to use the same subassembly in the 3-inch #6 dial, which was introduced after the #7 dial.
The 3" 6A dial (4-54) and the 4" 7A dial (4-53) apparently use the same gear arrangement.
(Differences are due to the slightly different camera angles.)
Casting and contact subassemblies are obviously different.
6A and 7A dials

1948 Housing (Pre-production)

[Photo Wanted]
1949 (Early Production) and 1950 (Production) housings were the same.
Housing, March 1949

Housing, inside, March 1949
Circular stiffener in lower right is for a hole for the (future) line switch.
Switchhook plungers were changed from clear to black.

1948 D-177006 Ringer (D177001 set - Pre-production)
D177001 Ringer
Note: Only 1 screw attachment point - changed to two (below).

1949 C2A Ringer  (Early Production)
C2A Ringer, April 1949
1950 C2A Ringer  (Production)
1950 Ringer
Three grommet ringer supports pressed into base were replaced by 2 captive grommets

1948 D-177018 Equalizer (D177001 set - Pre-production)
Internal Equalizer Components.
Equalizer Components
1949 (Early Production) and 1950 (Production) 311A Equalizers were the same
WE 311 Equalizer
(Bill Geurts photo)
Varistor screw attachment to can was eliminated.

Date      Source*         Topic                                               
49/02    IB News         500 coming “Leak” – “still in design stage”
49/03/16 BTL             Press Release – New Telephone Instrument
49/04    NE TelTopics      - New Telephone Instrument, p 15
49/05    BLR               - New Telephone Instrument
49/05    IB News           - New Telephone Instrument
49/05    PacTel Mag        - New Telephone Instrument
49/05    BTL             Notes on Discussion at the Conference of BS Lecturers
49/06    Popular Science New Phone Rings Loud or Soft, p 108.
49/12/12 Life Mag        New Telephone, p. 67  (also see p. 128 Dooner, yellow)
49/12/29 News Letter     Field Trial in St. Louis (AT&T Archive)
50/02    BLR             Cover Photo (Pre-production set)
51/01    BSTJ            “The Ring Armature Telephone Receiver,” p 110
51/04    BSTJ            “75 Years of the Telephone,” p215
51/04    BSTJ            “An Improved Telephone Set” (500), p 239
                               Trials, 48 & 49, pre-production sets, 4000 in 49
51/aut   BTM             “A New Telephone” (500), p 164
52/05    BLR             “Dial for 500 Type Telephone Set” (7A), p 211
53/03    Ohio Bell       510 in production, p 42
53/05    BSTJ            “An Improved Circuit for the Telephone Set” (425B net), p 611

54/03    WE Mag          p.7 (Manufacturing Locations)

55/sum   BTM             "Designing the Telephone" (from Dreyfuss book)

Designing for People, Henry Dreyfuss, 2003, pp 106-7. 

Old Time Telephones, Ralph Meyer, 2005, p 88,  p121 (dialing dots).

Singing Wires, Jan - Aug 2009, Series on 500-series history.
Singing Wires, Nov 2004, Henry Dreyfuss.

* Source Abbreviations:
  BLR - Bell Laboratories Record
  BSTJ - Bell System Technical Journal
  BTM - Bell Telephone Magazine
  Other sources are Bell System press releases and employee magazines.
      e.g. IB - Illinois Bell,  NE - New England Tel,   WE - Western Electric

Date format: YY/MM/DD, or YY/season

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©2010-14 paulf.  All rights reserved.