LOCATION : Part of Radio Room 1

YEAR OF INSTALLATION : 1952 with additions in 1957 and 1962. Radio equipment restoration completed April 17, 1993.


PURPOSE OF THIS ROOM : .This was the main focal point for the processing, distribution and filing of all messages that were sent to or from the ship by radio, flashing light, flags and (in harbour) messenger. The area around the desk in Radio 1 was designated as the Message Filing Area per the note on the drawing. The Message Centre contained much of ship's radioteletype (RATT) equipment with the remainder being located in Radio 2. When Radioteletype (RATT) was first introduced to the fleet, broadcast traffic could be cleared at speeds of 60 wpm as compared to the 25 wpm speed of the CW fleet broadcast. Teletype equipment was manufactured by the Teletype Corp. of Skokie Illinois.

TELEPHONE CONNECTIONS: Telephone D10 connects with Radio 2 and Radio 3.



The above configuration, circa WWII,  reflects Wireless Radio Office #1, later renamed to Radio 1. In 1952, space for the Message Centre was reclaimed from the port to starboard passageway located midships. The ammo hoist could not be moved so it remained in its original position but the WTS hatch cover in the upper right potion of the photo was removed. The door to Radio 1 was moved slightly forward. One half of the bulkhead (port side) was erected by 1952. At some later date, perhaps in 1962, the remainder of the bulkhead was erected. (Drawing from HMCS HAIDA archives) 
This 1957 configuration is a different arrangement than what we see today. Only  part of the bulkhead that separates the Message Centre is in evidence. The remainder of it would be added in 1962 when the navy had to convert this area to handle on-line broadcast crypto. The Message Centre also had a desk  After 1962,  message handling was transferred to the area at the desk in Radio 1. (HAIDA archives drawing) 

1957: HAIDA's radioteletype bay consisted of the exact equipment shown in this photo but not in the same sequence. Top to bottom: CSR5A Speaker, CSR5A receiver, Northern Radio FSC107 converter, Technical Materials Corp   Model SFO-2 teletype regenerator and the  AN/SGC-1A Radioteletype Terminal Set. (RCN Photo)

msg_centre_1957s.jpg By 1957, the RATT bay looked like this.  Click on image to enlarge. (HAIDA archives drawing) 

AN/SCG-1  A radioteletype terminal set.  See description in 1962 section.
CSR5A receiver. See description in 1962 section.
FSC107 Frequency Shift Converter. See description in 1962 section.

Model SFO Teletype Regenerator.

Model SFO teletype regenerator. The front panel door in the down position.  (Photo courtesy TMC) 

According to BRCN 5422 , bias distortion is the lengthening of the mark or space signal at the expense of the other. For an acceptable minimum amount of errors, the teletype signal must not have more than 5% bias distortion. There are three sources that contribute to distortion - mechanical, electrical and propagation., however BRCN 5422  dwells on the discriminator circuits in the Frequency Shift Converter as being problematic.

To correct bias distortion, a regenerator was placed between the Frequency Shift Converter and the teletype machine. The SFO is capable of accepting teletype signals in audio (on-off) form or in direct current form (polar and neutral) and having up to 45% bias distortion. When regenerated, the output signal will have less than 5% distortion. Made by Technical Material Corp.

* Accepts 60, 75 and 100 wpm teletype signals.
* Input keying - 500 to 3 KHz tone, 30 ma polar, 60 ma neutral, simplex or diplex
* Power input: 105 to 125 VAC, 50 to 60 Hz;  85 watts.

Once  encrypted broadcast was introduced in 1962,  the SFO was no longer needed as the regeneration of a teletype signal was handled by the KWR-37 crypto receiver.


Radioteletype (abbreviated as RATT in the RCN) was already installed in HMCS Buckingham in 1954 as recalled by  Radio Op Denies Stapleton. Over the next few years  broadcasts were sent over the RATT circuit along with the normal CW broadcast until all designated ships had RATT capability and the system proven reliable.

Sitting on the table is the Model 14 Reperforator  which allows an operator to create a punched paper tape with a message on it.  This tape would then be mounted unto the Model 14TD (Transmitter- Distributor aka tape reader) where it awaited transmission. Once the operator started the tape reader, an electrical signal (Baudot code) was sent to Radio 2 via hardwired cable, That signal was then converted into RATT form by a Frequency Shift Keyer  which in turn keyed the 500 watt PV500 transmitter.

RATT broadcasts could also be copied on  LF or HF and printed on one of the two teleprinters. It was a case of copying one broadcast or the other but not both. A  thick, black jacketed cable permitted the selection of either the LF or HF receiver output to the input of the Frequency Shift Converter.  Encrypted broadcasts were automatically decoded by the KWR-37 on-line crypto receiver. Two of these were situated in racks on the starboard side of the Message Centre.  Unfortunately, examples of the KWR-37 are unobtainable at this time,

Mounted on the port bulkhead of the Message Centre is the TT-23 Teletype Distribution panel. Using patch cords terminated with male telephone jacks, this facility  permitted the radio ops to reconfigure the interconnection of RATT equipment within the Message Centre to suit operational needs.

msg_centre_block_1s.jpg 1962: Message Centre System Diagram. Click on image to enlarge.  The bulk of the RATT  system is in the Message Center. Only the frequency shift exciter and RATT transmitter are located in Radio 2. (Drawing by Jerry Proc) 

For a PDF version  of this drawing, please select this link

Port side view of the Message Centre showing (L-R) Model 15 KSR Teleprinters , Model 14  reperforator. A Model 14 T-D sits on a shelf at the top right. (Photo by Jerry Proc)

haida_message_centre_rack_s.jpg 1962: This is the radioteletype bay in the Message Centre. From top to bottom:
Speaker panel. A switch permits either the LF or HF receiver to be monitored but not simultaneously;  AN/SGC-1 terminal unit, CSR5 receiver, FSC107 Frequency Shift Converter, RAK receiver, RAK5 power supply and CSR5 power supply. Click to enlarge. (Photo by Jerry Proc)


1.2.1 - AN/SGC1A Radioteletype Terminal Set 

sgc1a.jpg VHF and UHF radioteletype was used for short range fleet broadcasts in the 225 to 400 MHz UHF band. It was very likely that the escort force commander would want to have a UHF RATT circuit dedicated for his use with his screening ships in addition to a tactical, UHF voice circuit. One contributor suggests that RATT over UHF could have been used in harbour to relay broadcast messages between the Command Message Centre and ships in port. Can anyone confirm? (Photo by Jerry Proc)

Also, was there any off-line encryption applied to these RATT over UHF messages? Contact .

When a RATT message was to be transmitted, the teletype machine or paper tape reader (T-D) would interrupt a DC current loop based on the elements of the Baudot signalling code. The resulting pulses were applied to the input of an audio oscillator within the terminal set. These pulses then keyed the oscillator to produce either a 500 Hz or 700 Hz audio tone. When the loop was closed a 700 Hz tone was produced. A 500 Hz tone was produced when the loop was open. The 700 Hz tone was considered to be the MARK state while the 500 Hertz tone was the SPACE state. Alternately opening and closing the loop caused the output of the terminal set to toggle between 700 and 500 Hz, thus representing the Baudot code as a warbling audio tone. In turn, the audio output was applied to the microphone input of an AM transmitter.  This method of keying the transmitter was called Audio Frequency Shift Keying (AFSK) or "tone modulation" in its heyday. 

When traffic was to be sent, a control signal from the SGC1A placed the radio transmitter on the air until the messages had been transmitted. This control signal was activated by striking the space bar on the Teletype machine prior to sending traffic. Alternately, if the T-D was used was the input source, the first character on the tape would have to be a space character.

When receiving messages, the process was reversed. The SGC1A accepted the incoming mark and space tones from an associated AM receiver such as the AN/URR35A. These toggling tones ultimately controlled the keying of the DC current loop. This terminal set was manufactured by the Remler Co. Ltd. of San Francisco. The first examples of the AN/SGC1A were produced in November of 1950.

CSR5 Receiver

The sole purpose of this receiver was to receive high frequency RATT signals which provided input to the frequency shift converter. Normally, reception was crystal controlled, however, when crystals were not available, the CSR5 tuning control had to constantly be readjusted to maintain proper RATT reception. When CSR5 receivers were rack mounted, they were usually powered with a Marconi WE11 rack mounted power supply. This supply only operated from a 120 or 220 VAC power source. On HAIDA, a replica was constructed to replace the WE-11 unit that was missing.

KWR-37 On-Line Crypto Receiver

Code named JASON, the sole purpose of this unit was to automatically decipher the encoded RATT fleet broadcasts. On the input side, it was connected to the current loop output of a frequency shift converter. The output side was connected to a Teletype.  (Photo courtesy NSA)

The interconnection of the KWR-37 to the radio equipment. 


The shore station started each day's broadcast at 0000 Zulu and transmitted without interruption for 23 hours and 55 minutes each day. On shore, the encryption device such as a KWT-37 was synchronized with a time signal station (CHU or WWV) and the originating device sent an automatic 'start' signal followed by a continuous stream of encrypted, non-repeating traffic throughout the day.

The decoding 'key' which was similar to an IBM style punch card had a pattern of randomly punched holes, and had to be changed daily, prior to the start of the next day's broadcast. Encryption keys were changed by unlocking a front door on the KWR-37, removing the existing card, and installing the card that was designated for the next day. These cards were inserted behind a small door in the front of the KWR-37 using the built-in alignment pins. The door closed against a block of small, spring-loaded steel pins. Where a pin touched the paper card, no signal passed; where a pin poked through a hole in the card and touched a silver-plated metallic track, a circuit was made. Each card held enough keys to cover 14 years of usage before the key repeated itself. For very confidential messages, the fleet broadcasts consisted of encapsulated five character cypher groups which had to be decoded manually on a KL7 crypto unit. An example of this type of message would be the notification of death of a crew member's next-of-kin. Sometimes, there were periods were no messages were being sent on the Fleet broadcast and the Teletype would just sit there receiving null characters.

John Dill of Kingsville Texas, was a crypto machine mechanic in the USN in the 1960's and 70's, and kindly documented his experiences with the KWR-37. "The holes in the punched cards directed the key stream to a series of bistable multivibrators (flip-flops) which were wired on thirteen printed circuit boards located on the left side of the machine when one opened the equipment drawer. All the flip-flops plugged into a motherboard which was positioned horizontally. The active devices in these circuits were sub-miniature, type 6088, wire lead, sharp cutoff pentodes made by Raytheon or General Electric. These tubes were about 5/16 inch in diameter and 1 1/4 inches long and anchored by metal clips on each circuit board. The 6088 pentode was also known as type CK522AX. Depending on circuit design, the 6088 could be driven to produce as much as 10.5 mw of power at the high end or as little as 1.2 mw at the low end! One multivibrator stage consisted of two 6088 pentodes for the flip-flop and one 6814 sub-miniature triode amplifier, a vacuum tube originally designed for late generation tube computers. All stages had to be perfectly balanced, hence the use of resistors with 1% tolerance. Typically, the pentodes ran at 67.5 volts B+ and the triodes at 100 volts. There were four flip-flops per board and the entire unit contained approximately 500 tubes.

In addition to the operational key cards, there were also cards used strictly for testing. Each card in the test deck, checked a different KWR-37 function. Two of the cards, produced a distinctive pattern of beeps to indicate proper operation and the technician had to listen attentively. Used, operational cards were destroyed on periodic basis with two people witnessing their destruction, depending on the specific 'customer'. With care, the test cards could last for years.

The door for the key card was equipped with a lock in order to prevent anyone but authorized personnel from seeing the punch card. For security reasons, the card door was made from very thick steel. Details about the construction of this door are still classified since a similar arrangement was used on some newer machines. Affixed to the door, was a small placard with the letters NOF. This stood for 'Not for Observation by Foreign national'. It was permissible for a foreign national to view the front of the machine, but that same person would have to leave the premises if the front door of the '37 was opened for any reason.

When the '37 was first designed, an 'order wire' mode was incorporated. It was intended to pass plain text instructions to the distant station in order to bring up the system in crypto mode. These instructions were to be passed in the clear using code words. When the '37 went into service, the order wire was actually disabled.


Transmissions began at 0000Z and continued without pause or repetition for 23 hours, 55 minutes each day. Whether any messages were being sent or not, the 'customers' KWR-37's were on-line, in sync and receiving the transmitted key stream. In the event of a power loss or if the unit went out of sync, the operator would have to initiate a restart. When the sending station stopped transmitting, all receiving units worldwide would be prepared to receive transmissions for the next day. If radio conditions were normal, the transmitting station's Auto Start signal would automatically start the machine. If Auto Start was missed due to atmospherics, the operator had to late start the unit. This procedure is discussed further in the text.

On the front panel of the unit, there was a control composed of two concentric dials; the outer for hours and the inner one for minutes. Above that, were three miniature switches marked Start, Reset and Sync. Two small, orange lamps tagged Mark and Space flashed alternately in time with the incoming signal. Re- synchronization of the KWR-37 required that the machine be reset, then run it forward in time at high speed to catch up to, then slightly pass, the transmitting station's key stream. The operator would set the Hours/Minutes dials to the difference between 0000Z and the current Zulu time. The Hours dial was marked in 1 hour increments up to 23. Similarly, the Minutes dial was marked in 5 minute increments up to 55. The Reset switch would then be pressed. This would reset the flip-flops in the Key Generator and the Internal Clock and ensure that all these circuits started up from a desired, known, pre-set value. Internally, the reset signal was routed to the flip-flop stages through the Key Card, thus changing the initial 'set' state of the Key Generator. Pressing the Start switch would enable and start the clock which began to drive the flip-flop stages thus producing the key stream. Activating the Sync switch would give approximately 15 seconds worth of high clock speed, akin to a fast forward function.

If for example, the KWR-37 had dropped off-line at 14 hours into the broadcast day due to loss of ships mains power, and restoral took 15 minutes, the operator would set 14 hours, 15 minutes on the dials and hit the Start button. The machine would run in high speed for several minutes until the clock had advanced the key stream 14 hours and 15 minutes, at which time it would drop back down to normal speed and start searching for sync. This process forced the KWR-37 in constantly comparing it's own internal timing to that which was being sent on the broadcast. If a clock comparison was unsuccessful, the clock would delete a pulse, effectively dropping it back in time by a small amount. Each time this pulse deletion occurred, an audible beep was sounded through a panel mounted speaker. As the beep rate slowed, it told the operator that synchronization was approaching. After several seconds of silence the Sync light would illuminate and the Teletype attached to the '37 would start printing.

If the search for synchronization ran over several minutes duration, the '37 would alarm again with a steady, irritating, much-hated tone from the speaker along with the dreaded red Alarm light. Standard procedure called for resetting the machine and trying again. Since no two KWR-37's were exactly alike, the presence of the alarm did not mean that the machine stopped searching for sync. The alarm simply meant that the allotted amount of time had elapsed, during which, synchronization should have been attained. In many cases, the '37 achieved sync with the alarm sounding and the SYNC light on. At this moment, the operator would silence the speaker and everything would run normally. This was the official procedure for achieving synchronization.

In practice, however, it was an entirely different world. An operator would generally attempt the formal procedure. If this did not achieve results, a whole series of 'homebrew' remedies could be applied. Among these miracle cures for lack of sync were: a) Pounding the front panel briskly just prior to pressing the START switch.

b) Opening the equipment drawer and hitting the tops of the circuit boards with some hard object such as a mallet or cleaning brush.

c) Opening the front door; removing the key card and cleaning the conductive tracks in the rear of the front door with a rubber eraser. This practice removed the plated silver on the tracks and was frowned upon.

d) Cleaning the conductive tracks with Teletype paper or paper money. Since Teletype paper contained trace amounts of oil to assist with lubrication, this practice was highly discouraged.

e) Rapid and vigorous spinning of the time-delay dials, followed by many shots on the RESET button.

f) Uttering foul, abusive language at the machine in order to let it know who was in charge.


The KWR-37 was very old, tired and well past it's design life in 1968 and did not improve with age. Many technicians only had a modicum of training in the art of soldering. For the '37 family, this was a disaster as the most frequently performed corrective maintenance involved the replacement of wire lead vacuum tubes. One can only imagine the damage that was done to the printed circuit boards after 20 years of mediocre maintenance.

To ensure the highest reliability, crypto mechanics tried to turn out a machine capable of operating normally with only 1 volt of filament voltage to all the 6088 pentodes. The standard setting was 1.25 volts and was indicated by a front panel meter. Each pentode had a filament draw of 20 ma. If the unit ran properly at a reduced filament voltage, that meant that the tubes had strong emission and the unit would run reliably. As emission decreased, the operator could increment the filament voltage to restore normal operation. When the machine became unreliable at a setting of 1.25 volts, it was turned back to the maintenance depot. Checking for operation at a reduced filament voltage became known as margining. The 6814 triodes which used indirectly heated 6.3 volt filaments were not margined.

Later and unofficially, an extender board was developed which allowed individual circuit boards to be margined. Once each board ran reliably at one volt filament voltage, the filament supply to the entire machine was reduced. If it worked, it was considered ready for use. Testing each board individually improved the quality of the troubleshooting process. The majority of maintenance problems in the '37 originated in three areas of the machine: the 'S' circuit cards, (the ones containing the key stream flip-flops); the 'T' cards which combined the 'S' card outputs and the 'U' or alarm cards. Next, were the cards which allowed the '37 to run at high speed. The modified card extender was invaluable in finding these circuit faults and eventually won official approval. A maintenance bulletin was circulated among all KWR-37 holders documenting the modified extender, the construction details and stock numbers of the parts required".

John goes on to comment about his worst KWR-37 repair job." A technician had the '37 drawer open for maintenance. Innocently, a brand new Ensign, who was the Communications Officer noticed the activity and came over for a look. He must have been having a hard time at sea because of the large bottle of Maalox (stomach antacid) in his shirt pocket. As the Ensign leaned over to peek at the '37, the bottle fell out and broke on the top edge of the equipment drawer. Needless to say, the Maalox spilled throughout the machine and a large blue flash ensued as the power supply shorted out. Flames and smoke began issuing from the drawer. The tech had been sitting on the deck in front of the '37 cross-legged with his legs underneath the extended drawer. His burning trousers were quickly extinguished by the remainder of the Maalox running out of the equipment. In his haste to escape, the tech placed his full weight on the card rack and broke the motherboard in several places. The '37 was eventually repaired but the cost to repair, likely exceeded the value of the machine".

Mechanically, the '37 was about 22 inches wide, around 24 inches deep and 8 to 9 inches high with a case finished in navy cabinet grey. It was usually positioned on an equipment shelf. With a weight approaching 100 pounds, it was definitely a two man lift when it was being installed. All cabling plugged into the back of the unit.


In the RCN, there was one minor difference in the manner that the KWR-37 machines were operated. Gregory Mclean of Abbotsford BC details the difference and explains some operating practices. "In the RCN, the crypto cards were not destroyed daily. At the end of each month, when we had finished with that months pack, we returned them to the C.B. Officer (Confidential Book Officer). To ensure separation of duties, the CBO was not involved in communications. He was usually a junior officer with a number of unrelated duties. It was up to him to destroy used crypto and other classified materials at predetermined times. Sometimes, he requested help from communications branch personnel. On smaller ships, the CBO could be the Communications Officer.

The KWR-37's went out of sync frequently. Static or other interference could cause the machine to loose sync. One did not have to actually hear the hateful 'out of sync beeping'. You knew you had a problem when the teletype machine began printing garbage. It was possible to tell just from the sound. The MARK and SPACE lights on the face of the '37 flashed in sync with the incoming radioteletype signal. When out of sync, they glowed continuously and gloatingly.

In some installations, where diversity reception was fitted, two '37's copied the same broadcast on two different frequencies. It was rare to lose both signals simultaneously but if the entire broadcast was lost, and were in company with other ships, we could ask another ship for any of the missed messages. Alternately, reruns of the specific messages could be requested from the shore station. Sometimes, if a jackstay transfer was scheduled, the other ship could pass the missed messages by jackstay. We could not pass lost messages intership because intership crypto used an off-line machine and that could compromise the on-line system. If travelling alone, or everybody missed the messages, one ship would request the shore station, via ship-shore circuit, to rebroadcast the missing messages by referencing their sequence numbers.

I took my maintenance and repair course in Stadacona. We did six weeks in a secure room. There were no notes and nothing could be taken from the room. The exams were of the open book variety. On board ship when one had exhausted all means of repairing a blinking, beeping KWR, you shut it off. Sometimes when you turned it back on it worked fine. Other times, I exchanged certain circuit cards from a good machine to the unruly one. Cleaning the contacts behind the card door seldom worked. Sometimes we found small cracks in the key cards. We really did not have the proper equipment to repair 37's at sea".

During it's service life, the security of the  KWR-37 system was essentially compromised from 1968 to 1985. When the USS Pueblo was captured in 1968, the north Koreans acquired fully working KWR-37's along with active key cards.  (The Pueblo was a spy ship that went on a routine ELINT mission down the North Korean coast).

Naturally, there was a mad scramble to quickly change all of the cards held by KWR-37 'customers' all over the world. In the mid 1980's, it was discovered that the infamous 'Walker spy ring' was selling active key lists (ie the actual IBM style punched cards) to the Communists.  It must be assumed that this activity had trasnspired as early as 1968. Once again, the key lists had to be quickly changed. It's important to note that simply possessing a machine was insufficient to copy the traffic in the short term. Any adversary had to be in possession of the active key lists in order to immediately decode any traffic. When the ship was captured, the crew had no way of quickly destroying the classified materials, so the Koreans got it intact. When word got back to Washington that Pueblo was captured with a full fit of materials, all hell broke loose, world wide.

By the early 1990's, any remaining KWR-37 crypto receivers were taken out of service and destroyed. This sounds like a sad ending, but such is life in the world of cryptography.

In 1962, aboard HAIDA, a pair of KWR-37's were fitted on steel racks, and a canvas cover blocked them from view as the crypto receivers were considered top secret. One device was assigned for HF/LF decoding while the other unit served to decode UHF radioteletype traffic as implied by the existing wiring. If a Radioman who had security clearance for the coding systems left the RCN, it was mandatory that no information about the coding systems be divulged for a period of six years. As with the KL7 crypto machines, all of the KWR-37 crypto receivers fitted on Canadian ships was owned by the National Security Agency of the United States and was loaned to North Atlantic Treaty Organization member countries including Canada. 1.2.4 - Model 14 T-D (Transmitter-Distributor)A T-D is the official name for what is otherwise a paper tape reader. Perforated paper tape was fed into the transmitter- distributor for transmission of messages over a radio link. The tape was positioned under a clip and over a lineup of 5 metallic sensing pins. These pins opened or closed electrical contacts depending on the presence of absence of holes. A sprocket wheel fed the tape past the sensing pins and produced the Baudot code required for RATT transmission.

Model 14 Reperforator with Keyboard


A reperforator was a motor driven machine which generated punched paper tapes either from the keyboard or upon receipt of Baudot code from another device. Simultaneously, the unit printed the message on the tape. It is worthy to note that the printing lagged the perforated holes by six characters. Example - If the letter A was punched on the tape, it would be printed a distance of six characters later. (Photo by Jerry Proc)

Messages could be prepared in advance and sent at routine times. This would maximize system efficiency as the punched tapes could be checked for accuracy prior to transmission. Some of the tapes were used to call shore stations or other ships. Tapes could be formed into continuous loops when multiple passes of the same message had to be sent. An example of this would be a calling tape: CFH CFH de CGJD CGJD K . If these tapes became worn out, the reperforator could be connected up to the paper tape reader in order to regenerate the original tape.

Model 14 reperforators came in two types. They could either punch the tape all the way through or leave a small paper hinge attached to the chad.  The tape produced by the latter type was called "chadless tape, since the reperforator does not completely remove the circular piece of paper but leaves it secured to the tape by a small uncut portion of paper. Chadless tape had the advantage of tidiness but was somewhat awkward to roll up by hand. In addition, this “chadless” feature was important to enable characters to be printed on the tape six holes away from the associated character. Chadless tape was the only type used at sea.

The RCN actually encouraged Radiomen to read the chad type tape and encouraged them to keep a sample on hand at all times and study it during their spare moments!

Model KSR 15 Teletype

A teletype is little more than an electrically operated typewriter. The prefix tele means at a distance. Coupled with the word typewriter, it forms a word meaning 'typewriting from a distance'. Model 15 machines, originally installed around 1957, were capable of printing at 60 words per minute. In 1962, they were replaced with faster Model 28's as a pre-requisite for the new, now encrypted broadcast system called JASON. This system incorporated the KWR37 on-line crypto receiver. For purposes of metering transmission speed, a standard word was considered to be six characters in length.Normally, Model 15's had to be checked weekly and receive a tune up every month. The major maintenance interval was usually six months but could be shorter than that, depending upon the amount of usage. Machines were usually refurbished by returning the dirty or faulty mechanism back to a repair depot, removing the signalling coils and motor, and immersing the remainder in a 45 gallon drum of kerosene or diesel fuel for 24 hours. Several other drums would serve as rinsing stations. The mechanism, was then left to dry, followed by a complete tear down and inspection for badly worn or damaged parts. It was easier to do it this way, as opposed to searching for worn parts when the mechanism was in an assembled state. Afterwards, the mechanism would receive a generous coat of lubricating oil, followed by mechanical adjustments. Maintenance was normally handled by the " Green Empire" which was the Electrical Branch of the Royal Canadian Navy. If machine adjustments were required and the Green Empire was not available, then the adjustments might be attempted by the radio operators. (Photo by Jerry Proc)

Click on the Model 15 image to see and hear the sight and sound of a Model 15 Teleprinter at work. (Recorded by Jim Brewer)

There was one quirk about Teletype operation aboard ship. Because of the plane in which the Model 15 was mounted, the carriage in the machine would slow down in an upward pitching sea. Sometimes, the strain was so much that the drive gears would strip! This problem was overcome with the introduction of Model 28 teletypes. In this design, a bulky mechanical carriage was replaced with a small, lightweight 'print block'.

In order to avoid fatigue while operating the Teletype, good posture was very important. Function keys such as FIGS and LTRS could be very confusing to use when compared with a regular typewriter. It became important for the operator to practice and develop a good keyboard rhythm in order to overcome these problems. From a signalling viewpoint, the RATT system used the Baudot code in which mark and space conditions were converted to produce a signal that had a frequency shift of 850 Hertz. Back in the 1950's and 1960's when tube receivers lacked good stability, it was necessary to use a 'wide' frequency shift to compensate for receiver drifting. As receiver designs improved, a frequency shift of as little as 170 Hertz became popular because it used up less space in the radio spectrum. This became the standard radioteletype 'shift' in the amateur radio bands and remains to this day. There are still a few a few isolated commercial stations using wide shift teletype, but these too, will eventually become obsolete.

Model 15 schematic can be found here.


In 1962, as part of a fleet modernization, the 60 wpm Model 15 ASR teletypes were replaced with the faster Model 28 KSR teletypes. Trying to locate working Model 28’s (since 1992) has not met with any success, so the historically accurate Model 15 machines are on display in HAIDA's Message Centre.  (Photo courtesy Teletype Corp) 
 Model 14 T-D
mod14_td.jpg The Model 14 Transmitter-Distributor correct name for a paper tape reader. (Photo by Jerry Proc)
RAK Receiver 

rak5.jpg Designed in the 1930's, this six tube regenerative receiver was capable of receiving signals between 15 and 600 kc. Tuning was accomplished through the use of circular, geared logging scales for both coarse and fine tuning. To determine an actual frequency, one had to look at the dial reading then consult a 'tuning graph'. Since these graphs were not that accurate, most operators calibrated the receiver by noting the dial positions after stations of known frequency were identified. (Photo by Jerry Proc)

 In 1962, the RAK was added to the equipment rack in the Message Centre RATT bay.  It is assumed that the sole  purpose of this unit was to receive low frequency RATT signals and provide input to the Frequency Shift Converter after 1962. It still receives remarkably well despite its antiquated design. When compared to the CSR 5A, the RAK provides superior performance on the low frequency radio bands.The RAK aboard HAIDA was built by RCA Victor in Montreal and weighs 74 pounds. It is interesting to note that this receiver was still in use by the RCN in 1962. 

REC10 Rectifier - The REC10 was a rectifier that provided a 120V DC, 100 or 200 milliampere power source to the Teletype Distribution Panel. 

Speaker Panel in Rack The sole speaker in this rack was intended to monitor either the CSR 5A or RAK audio output by moving a jack to either receiver.

FSC107 Frequency Shift Converter

fsc107.jpg This unit converted RATT signals from either a CSR 5A or RAK receiver into pulses which controlled a current loop. In the case of HAIDA, the FSC107 had a dedicated connection to one of the teleprinters through the Teletype Distribution Panel. Audio input signals to this unit were represented with 2975/2125 hertz tones. The frequency difference between these tones is 850 Hz, hence defining the 'frequency shift' of the entire system. There was a small CRT mounted in the 107 unit which was used to monitor the quality of the received signal. (Photo by Jerry Proc)

Teletype Distribution Panel 

tt23.jpg The TT23-SG Teletype Panel was intended for general shipboard use to facilitate the interconnection of various pieces of equipment such as teletypes, frequency shift converters/keyers and tone terminals. There were six channels available and each channel could have its loop current monitored and adjusted individually. The Teletypes and the KWR-37's each had their own separate 'plug' boxes which could be interconnected to the panel. Equipment interconnections were dedicated and hardwired within the TT23. In case of equipment failure, the connections could be re-configured with the use of patch cords. Northeastern Engineering Inc. of Manchester, New Hampshire produced the first examples of these units in 1947 for the US Navy Department. The unit installed on HAIDA is S/N 182 dated 17/09/51. (Photo by Jerry Proc)


Man Aloft Board

This was a key depository (formerly called a key board) for all equipment which was equipped with "safe to transmit " keys. Cabinets for the Man Aloft Board came in all shapes and sizes. All radio transmitters had to be disabled while the ship was under any of the following conditions - being refuelled; refuelling aircraft; ammunition being loaded or unloaded; man aloft; ship being dressed; ship being lighted. When the keys were returned back to this panel, it signified that all radio transmitters and radar were secure. The key to the board was held by the Officer of the Day in harbour or the Officer of the Watch while at sea.

Safety precautions were also necessary whenever personnel were working aloft. Aloft, meant anyone working above the flag deck level. One hazard to be reckoned with was the fact that the 35 foot whip antenna presented a potential danger within a ten foot radius if the frequency was above 10 MHz. Did the navy know something back in the 1960's or was this a general precaution ? From radar, there was a two-fold hazard. One had to worry about radiation and mechanical antenna rotation.

When aloft, it was stressed that safeguards must be taken against electrical shock, falling, choking from funnel gas and the dropping of tools. Personnel aloft had to be supervised at all times. There was a documented case in the United States Navy, of a man who was working aloft while the funnel exhaust was blowing his way. He worked in the fumes for a half hour and then came down complaining that he couldn't stand it any longer and would have to wait for the wind to change. About an hour later, he collapsed and was taken to hospital where he died later that day.

An actual Man Aloft board  as seen in the Message Centre of HMCS HAIDA. (Photo by Jerry Proc) 

Cdr. Bob Willson seems to recall there might have been a duplicator (mimeograph machine) in the Message Centre. "There may have been a duplicating machine in the Message Centre and another near the Coxswain's/Regulating Office. The communicators used theirs to duplicate messages. Several copies would be circulated - one for the Daily Log which went to the CO and then to the various officers, one for the log in the Message Centre, one for the "Action Officer" or  the Ops Room log, etc. The other was used to print daily orders, which were posted throughout the ship. Captain and XO's Temporary Memoranda, and multiple copies of letters would also reproduced by machine in the event that too many carbon papers had to be loaded into the typewriter".

Contributors and Credits:
1) Merv Cameron <mdcameron(at)>
2) Pat Barnhouse <pat.barnhouse(at)>
Back to Table of Contents
May 2/19