1. CROSS REFERENCES FOR COMMERCIAL AND SIGNAL CORPS NOMENCLATURE

Hammarlund Commercial          Equivalent Signal Corps
Nomenclature                             Nomenclature
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SP-210-LX                                 BC-779-A
SP-200-LX                                 BC-779-B
SP-210-SX                                 BC-794-A
SP-200-SX                                 BC-794-B
SP-210-X                                    BC-1004-B
SP-200-X                                    BC-1004-C and -D
NONE                                          R-129/U
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NOTE: When an R appears in the Hammarlund commercial Model, such as
SPR, it indicates that the equipment is a rack model rather than a
table model. All SP and SPR models are considered to be identical.

2. DIFFERENCE IN MODELS

  a. The external appearences of the receiver and power supply units
for all models are practically identical except that Radio Receiver
BC-1004-D does not contain the S meter. The various models can be
rack or table mounted.

  b. Radio Receivers BC-779-A and -B are alike, Radio Receivers
BC-794-A and -B are alike, and Radio Receivers BC-1004-B and -C are
alike with the exception that in the later issues of each model,
potted type transformers and chokes with terminal boards are used in
place of leads.

  c. Radio Receiver BC-1004-C and -D are identical except for the S
meter.

  d. Radio Receiver R-129/U is exactly the same as Radio Receiver
BC-1004-C except for frequency coverage.

  e. Radio Receivers BC-779-(*), BC-794(*), BC-1004(*), and R-129/U
are funcitionally alike except for the differences in frequency
ranges.

3. FREQUENCY COVERAGE BY MODEL

SP-200-LX       100-200Kc   
SP-210-LX       200-400Kc
BC-779-(*)         2.5-5Mc
                              5-10Mc  
                            10-20Mc
               

SP-200-SX    1,250-2,500Kc
SP-210-SX        2.5-5Mc
BC-794-(*)             5-10Mc
                             10-20Mc
                             20-40Mc
R-270/FRR is a BC-794(*) modified for dual diversity operation with
external master oscilator and was part of the AN/FRR-12.
              
SP-200-X        540-1,160Kc
SP-210-X     1,160-2,500Kc                       
BC-1004-B       2.5-5Mc
                             5-10Mc
                           10-20Mc

R-129/U        300-540Kc
                      540-1,160Kc
                   1,160-2,500Kc
                       2.5-5Mc
                          5-10Mc

4. POWER SUPLIES

There are three major AC power supplies associated with this series
of receivers with the primary difference of input AC voltages and and
power line frequency.

  a. Power Supply Unit RA-74-(*) furnishes AC and DC operating
voltages for radio Receiver R-270/FRR, or radio Receivers BC-779-A,
-B; BC-794-A,-B; BC-1004-B, -C, -D; and R-129/U.
       Output  380 VDC at 50ma
               250 VDC at 100ma
               100 VDC at 4.5ma
               -50 VDC at 11ma
               6.3 VAC at 7A
      Input    95/105/117/130/190/210/234/260 VAC
               25-60 cycle AC

  b. Power Supply Unit RA-84(*)  furnishes AC and DC operating
voltages for radio Receiver R-270/FRR, or radio Receivers BC-779-A,
-B; BC-794-A,-B; BC-1004-B, -C, -D; and R-129/U.
       Output  380 VDC at 50ma
               250 VDC at 100ma
               100 VDC at 4.5ma
               -50 VDC at 11ma
               6.3 VAC at 7A
       Input   105/115/125 VAC
               50-60 cycle AC

  c.  Power Supply Unit RA-94(*)  furnishes AC and DC operating
voltages for radio Receiver R-270/FRR, or radio Receivers BC-779-A,
-B; BC-794-A,-B; BC-1004-B, -C, -D; and R-129/U.
       Output  380 VDC at 50ma
               250 VDC at 100ma
               100 VDC at 4.5ma
               -50 VDC at 11ma
               6.3 VAC at 7A
       Input   115/230 VAC
               50-60 cycle AC

  d. This series of receivers may also be operated from DC batteries.
       One 6 volt storage battery for A+ filament supply
       Five 45 volt B batteries for B+ supplies
       One 45 Volt C battery for C- supplies

5. IMPROVEMENT KIT MC-531

  a. The Improvement Kit MC-531 is designed to stabilize the
operation of the radio receiver under conditions of varying line
voltage and ambient temperature changes by means of a crystal
oscillator which provides for crystal-controlled reception at any one
of the three signal frequencies, in the frequency range of 1.5 to 20
Mc. It has a delta tuning control to make slight adjustments to the
received signal.


Some more trivia,

MACKAY RADIO AND TELEGRAPH COMPANY
HF COMMUNICATIONS RECEIVER
MODEL CNY-1176B (SP-400-X)
Modified for FSK using Northern Radio HFO/BFO Master oscilator.

Additional modifications included:

MACKAY Model BNY-1798 Mechanical Filter Adapter. This removed the
Crystal Selectivity Filter assembly and replaced it with a Collins
1.8 Kc BW mechanical filter (F465K25).

Another MACKAY modification replaces V1 6K7 1st RF Amplifier with a
12AT7 Cascade 1st RF Amplifier.

RICH  WA6KNW

The Hammarlund Manufacturing Company

Oscar Hammarlund started the Hammarlund Manufacturing Company in 1910. In the 1920´s the Company, through an affiliate, Hammarlund-Roberts, Inc., manufactured broadcast receivers, and  Hammarlund Mfg. Co. marketed components such as variable capacitors, coils and dials. The Hammarlund-Roberts name disappeared about 1932. The two Companies used the same address on West 33^rd Street in New York City.

Late in 1931 Hammarlund introduced the "Comet" receiver, perhaps the first superheterodyne communications receiver. They followed in the spring of 1932 with the improved "Comet Pro" model which continued in production, with variations, until 1935.

Design of the best known and long lived receiver in the Hammarlund line began in 1933. This was to be the ultimate Receiver and was originally called the "Comet Super Pro" but it eventually became simply the "Super Pro". Like National, Hammarlund took an uncompromising approach to receiver design. They used special custom built components. They designed a unique bandswitching system, special IF transformers, and a twelve gang tuning capacitor. Originally scheduled for release in early 1935, the receiver was not ready for delivery until mid-1936.

Hammarlund continuously updated the "Super Pro" and its descendents were in production until 1937. The original 1936 model was designated the SP-10 series. The SP-100 appeared in 1937, SP-200 in 1939, the SP-400 in 1946 and the SP600 in 1950.

Beginning in 1955 Hammarlund manufactured a full line of receivers, most of them bearing the HQ prefix. Only the above models are descendents of the HQ-120.

The only other notable Receiver in the Hammarlund line was the "Pro-310" which appeared briefly from 1955-57. It was a top-of-the-line receiver with a unique two dial tuning system. For unknown reasons its life was very short.

Time started running out for Hammarlund, as it did for the other communication receiver manufacturers, in the 1950´s and 1960´s. The Company introduced a solid-state ham receiver, the "HQ-215", in 1967 but it was not successful and they dropped out of the ham market after that althought continuing to sell the "HQ-180" and the "SP-600 until about 1973. The Hammarlund Name then disappeared from the scene after more than 60 years.

Hammarlund had begun transferring its manufacturing operations from New York City to Mars Hill, NC, in 1951 and completed the move in 1959. By 1965 all the management functions had also moved to Mars Hill. During its final two decades Hammarlund was sold a number of times. Telechrome purchased them in the late 1950´s and then sold to Giannini Scientific in 1962 and who in turn sold to Electronic Assistance Corporation in the late 1960´s.