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---------------------------- Original Message ----------------------------

Subject: [ARC5] A.R.C. Type K "Command Set" Receiver History (KK5F) - Long

From: "Mike Morrow" <>

Date: Sun, February 10, 2013 8:23 am




There have been recent requests for various details of the RAT/RAT-1,

RAV, ARA/ATA, and other components descended from the A.R.C. Type K.

The following is a tabulation of the various forms that the A.R.C. Type K

command set receivers have taken between 1936 and 1950. The descriptions

are mine, based on the best information I have accumulated in the past 30

years or so. There will likely be some disagreements with information

presented, especially in the RAT/RAT-1 and RAV sections. There may also

be some need for correction of details. I gladly solicit comments and

criticisms of content and conclusions. Such have helped my understandings

on many occasions in years past. The comments below do not come from a

burning bush in the desert. :-)


Mike / KK5F

Revision 20130209



RAT/RAT-1, RAV, ARA/ATA, SCR-274-N, AN/ARC-5, Type 12/15 Receiver Chronology


A. USN A.R.C. Type K Command Set (1938)


Other researchers have shown that development under US Navy contract of

the ancestor to receivers now known as "command sets" began as early as

1936 by Aircraft Radio Corporation (A.R.C.) as the Type K command set.

This was not a production set, and apparently the design, as far as it

went, was concluded by late 1938. See Mike Hanz's web page

for a look at four Type K receivers, covering:


Type K Model 2 200 to 580 kHz

Type K Model 2 520 to 1500 kHz

Type K Model 2 3.0 to 6.0 MHz

Type K Model 2 6.0 to 9.0 MHz



B. SIDE NOTE - Contemporary Liaison Transmitter Requirements


B.1 USN GO-3 (1937) Liaison Transmitter


Westinghouse produced the GO-3 liaison transmitter, which is the last GO-*

transmitter whose upper limit was 13.575 MHz.

1937 GO-3 .300 to .600, 3.000 to 13.575 MHz



B.2 USN GO-4 (1938), -5, -6 (1939) Liaison Transmitters


General Electric produced the GO-4, GO-5, and GO-6 liaison transmitters.

1938 GO-4 .300 to .600, 3.000 to 26.500 MHz

1939 GO-5 .300 to .600, 3.000 to 26.500 MHz

1939 GO-6 .300 to .600, 3.000 to 26.500 MHz


All earlier GO-* liaison transmitters had an upper frequency limit of

13.575 MHz. Coverage of all RU-* liaison receivers (RU-4/5/6/10/11/12/18/19)

ends at 13.575 MHZ. The new GE transmitters created a need for additional

liaison receiver coverage from 13.575 to 26.5 MHz. To satisfy that need,

A.R.C. in 1939 developed the Type K based RAT (12-vdc) and RAT-1 (24-vdc)

receivers with almost precisely that coverage, from 13.5 to 27.0 MHz. The

RAT could be paired with A.R.C.'s 1939 RU-11 (12-vdc) or RU-12 (24-vdc) to

provide a liaison receiver system that fully complemented that of the



Doubtless, A.R.C. could foresee that other (future) liaison transmitters

systems would require receiver coverage above 13.575 MHz. That happened

with the Westinghouse GO-7, GO-8, and GO-9 (all 1940) and the Collins ATC

(1942), all of which operated up to 18.1 MHz.



C. USN RAT and RAT-1 (1939) Liaison Receivers


Two-receiver RAT and RAT-1 liaison receiver systems were made by A.R.C. in



The RAT (12-vdc) receivers are:

CBY-46083 13.5 to 20.0 MHz

CBY-46084 20.0 to 27.0 MHz


The RAT-1 (24-vdc) receivers are:

CBY-46108 13.5 to 20.0 MHz Same receiver as used in RAV below

CBY-46109 20.0 to 27.0 MHz Same receiver as used in RAV below


These are the first production versions of Type K designs which ultimately

led to

the "command set" receivers that were made in the millions by 1945. But


first production set was a liaison service set, not command service.


Only 50 each of RAT and RAT-1 were built, but it's likely that only small

numbers of

the GO-4, -5, and -6 transmitters were built as well.



D. USN RAV (1940) Liaison Receivers


In 1940, the 24-vdc RAV system was introduced. The RAV was A.R.C.'s

liaison receiver

system which totally abandoned A.R.C.'s 1930's RU system's TRF/plug-in

coil design.

The RAV covers the complete range of contemporary liaison transmitters by

using eight

of the latest Type K based receivers.


The RAV receivers are:

CBY-46102 190 to 550 kHz

CBY-46103 520 to 1500 kHz

CBY-46104 1.5 to 3.0 MHz Same receiver as used in ARA below

CBY-46105 3.0 to 6.0 MHz Same receiver as used in ARA below

CBY-46106 6.0 to 9.1 MHz Same receiver as used in ARA below

CBY-46107 9.0 to 13.5 MHz

CBY-46108 13.5 to 20.0 MHz Same receiver as used in RAT-1 above

CBY-46109 20.0 to 27.0 MHz Same receiver as used in RAT-1 above


The CBY-46108 and -46109 are also part of the RAT-1, while the CBY-46104,

CBY-46105, and CBY-46106 are also part of the ARA. There is no 12-vdc


of the RAV. The RAV is designed for local control only and is *not* provided

with any components for remote control. Only 46 RAV sets were made.



E. SIDE NOTE - A Competing Liaison Receiver


E.1 USN RAX-1 (1940) Liaison Receivers


General Electric produced the three-receiver liaison receiver RAX-1 whose

coverage complements the complete coverage of their GO-4/5/6 liaison

transmitters. Its coverage and intended use is identical to that of the RAV.


The RAX-1 liaison receivers are:

CG-46115 0.2 to 1.5 MHz

CG-46116 1.5 to 9.0 MHz

CG-46117 7.0 to 27.0 MHz


GE's RAX-1 and A.R.C.'s RAV may be seen as direct competitors to each other.

The last two RAX-1 receivers utilize two RF and three IF stages, in contrast

to the one RF and two IF stages of any RAV receiver. The tuning band spread

of the RAX-1 is better than the RAV. The RAX-1 requires three small


the RAV eight. The RAX-1 utilizes 22 vacuum tubes, the RAV 48. The overall

power consumption, weight, and volume of the RAX-1 is superior to the RAV.

t is little wonder that the RAX-1 easily won in competition with the RAV,

and saw widespread utilization by the tens of thousands...but the RAV only

by 46.



F. USN ARA (1940) Command Receivers


In 1940, the 24-vdc ARA system was introduced with the ATA transmitter


The ARA/ATA is the first production command set" version of Type K

based design,

consisting of five receivers:


CBY/CCT-46129 190 to 550 kHz

CBY/CCT-46145 .52 to 1.5 MHz

CBY/CCT-46104 1.5 to 3.0 MHz Same receiver as used in RAV above

CBY/CCT-46105 3.0 to 6.0 MHz Same receiver as used in RAV above

CBY/CCT-46106 6.0 to 9.1 MHz Same receiver as used in RAV above

(CCT indicates receiver made by Stromberg-Carlson)


The CBY/CCT-46145 broadcast band receiver was always supplied with the


power adapter panel for service with the ZB-* VHF homing adapter.


The two ARA receivers CBY-46129 and CBY-46145 are identical to the RAV


CBY-46102 and CBY-46103 *EXCEPT* that the loop antenna connection posts

and switch

are removed for the ARA version. The ARA command receiver system, unlike

the RAV

liaison receiver system, was provided with components required for remote


Local control adapters are not part of the ARA.



G. USAAF SCR-274-N (1941) Command Receivers


In 1941, A.R.C. developed a USAAF version of the USN's ARA/ATA command set

as the

SCR-274-N. It ultimately consisted of four receivers:


BC-453-A, -B 190 to 550 kHz

BC-946-B .52 to 1.5 MHz

BC-454-A, -B 3.0 to 6.0 MHz

BC-455-A, -B 6.0 to 9.1 MHz


SCR-274-N receivers and transmitters are identical to their ARA/ATA


except that the ARA/ATA utilize low impedance (300 ohm) AF while SCR-274-N -A

model receivers utilize high impedance (4000 ohm) AF. Later -B model


could be wired for either high or low impedance AF. Paint finish and minor

mechanical details, plus the eventual elimination of the local/remote

switch on

the antenna relay, and the elimination of the antenna relay vacuum capacitor

(on -AM model), illustrate some other minor differences between ARA and


versions of the SCR-274-N.


The BC-946-B broadcast band receiver was always supplied with the FT-310-A

power adapter panel for service with the AN/ARR-1 VHF homing adapter.


Some SCR-274-N receivers were made by A.R.C., some by Colonial Radio, Lewyt

Corporation, and other contractors. By far, most were made by Western




H. USN AN/ARC-5 (1943) Command Receivers


In late 1943 the US Navy received the first units of the "improved"

ARA/ATA, the

final MF/HF command set system used by the USN. This is the AN/ARC-5.


VHF components, these are:


R-23/ARC-5 .19 to .55 MHz [or improved R-23A/ARC-5]

R-24/ARC-5 .52 to 1.5 MHz

R-25/ARC-5 1.5 to 3.0 MHz

R-26/ARC-5 3.0 to 6.0 MHz

R-27/ARC-5 6.0 to 9.1 MHz

R-148/ARC-5X .19 to .55 MHz [12-vdc version of R-23A/ARC-5]


Most LF/MF/HF AN/ARC-5 components were made by A.R.C. or Stromberg-Carlson.


The loop posts/switch of the RAV re-appeared on the R-23, R-23A, R-24, and


These four receivers were also wired to serve as a MF localizer receiver

for the

short-lived AN/ARN-9 Air-Track ILS, by using the audio adapter panel


All receivers had AVC, which required a minor change in tube line-up.

Most R-25,

R-26, and R-27 receivers have "stabilization" modifications to allow preset

locked-tuned operation of these communications receivers. Those mods are


by a yellow circle-S stamp on front.


The R-24/ARC-5 broadcast band receiver was always supplied with the


power adapter panel for service with the AN/ARR-1 VHF homing adapter. It is

unlikely that many R-24 units were used in that application, since the

much more

versatile AN/ARR-2 all-in-one VHF homing receiver was available for


in AN/ARC-5 receiver racks about the time that the AN/ARC-5 was placed in




I. A.R.C. Type 11/12 (1946)


I.1 A.R.C. LF/MF Navigation Receivers


The only post-war legacy of the LF/MF/HF Type K design (outside the

components used

in the mid-1950s RT-427/ARC-39) is the commercial and military A.R.C. Type


LF/MF navigation receivers, available in 14-vdc or 28-vdc models: These


have neither BFO circuitry nor (after early versions) local indicating

dials. All

connections are made at the front panel, including a BNC loop connection.


R-10A .52 to 1.5 MHz

R-11A .19 to .55 MHz {JAN nomenclature R-510/ARC (14-vdc) or

R-511/ARC (28-vdc)]

R-22 .52 to 1.5 MHz



I.2 A.R.C. VHF Receivers


Although the intent of this write-up is not to discuss VHF receivers,

since those

are the most common A.R.C. Type 12 or 15 components encountered here are some



A.R.C. VHF receivers in Type 15 VOR/LOC sets:

R-13 108 to 135 MHz JAN nomenclature R-445/ARN-30 (28-vdc)


A.R.C. VHF receivers in Type 12 COMM sets:

R-15 108 to 135 MHz JAN nomenclature R-509/ARC (28-vdc)

R-19 118 to 148 MHz JAN nomenclature R-507/ARC (14-vdc), R-508/ARC




J. USAAF Oddities Made From The SCR-274-N Set


J.1 USAAF - UK Standard Beam Approach (SBA) Receiver (1942)


Some BC-455-B receivers were modified in the UK to cover 28 to 41 MHz for the

Lorenz type of directional VHF (dot-dash) beams used in the UK for


instrument approaches using the Standard Beam Approach (SBA) system.

Externally, the modified receiver had a dial calibrated from 28.0 to 41.0 MHz

plus a UK-style antenna connector on the left side. It was stamped MOD


It is unknown who performed these conversions or how many were made.


BC-455-B MOD CBA 28.0 to 41.0 MHz


Gordon White addressed details of these in "CQ Magazine", June 1968.



J.2 USAAF - AN/ARA-1(XA-1) Radio Compass Adapter (1943)


The AN/ARA-1(XA-1) utilizes a loop-fed BC-453-B and/or BC-946-B with a


adapter (modulator) to control an aural output and visual LEFT-RIGHT beam

indicator meter. Details of the modifications required for the receivers

is unknown to me.



J.3 USAAF - AN/CRW-3 Guided Glide Bomb Control (1944)


Some SCR-274-N BC-454-B and BC-455-B receivers were incorporated into the


bomb radio control system AN/CRW-3. This control system was part of the

late-WWII GB-4 glide bomb. The standard receivers were modified slightly to

provide a connection to the RF and IF stages for an external electronic gain

control signal from AM-41/CRW-3. The dial was removed except during


adjustment. The original nomenclature was altered with a paper tag to end


a -BM. The receivers were mounted in special mountings for the



BC-454-BM 3.0 to 6.0 MHz

BC-455-BM 6.0 to 9.1 MHz


Dave Stinson at one time posted on his web pages a copy of the operating

instruction manual for the AN/CRW-3.