i can solve all two hundred yards short long before pearl harbor the signal corps of the united states army you it would take more than a telephone wire to connect this voice with all the other fighting units that had to hear it they knew it would take radio transmission radio can reach these tanks wherever they are and tell them what's ahead a radio transmitter could coordinate the movement of troops bring tanks and infantry to gather at the right place at the right time but it would have to be a mobile radio transmitter and it would have to be a powerful transmitter to keep an eye on broken contact between our forces on the ground in the air and on the se the control widely separated forces the timing of their action the success of the attack depends upon reliable radio communication yes the signal caller engineers knew just what kind of a transmitter it would the signal corps found many of the answers it was designed especially for amateur use it was easily capable of worldwide communication using either coast or voice another great advantage was the fact that this how a crafters unit at been on the market for several years there was an opportunity to check its performance through the records of hundreds of america's hands and these amateurs know good performance south africa these were regular almost daily experiences in many amateurs homes where hallicrafters were rapidly shrinking this old world of ours the transmitter that served the army must be able to perform anywhere and under all kinds of unpredictable conditions up to this time no one had ever thought seriously of putting this sensitive finely balanced instrument on wheels and bouncing it around fox chief engineer and the hard pressed technicians of the signal corps never few changes needed to adapt this unit to army needs there was good engineering and good sound instruction in the set to start with this was to be the new home for hallicrafters equipment everything needed to transmit and receive had to be packed into this small space that would take some more good engineering this demand was nothing new to these pioneers there are no fixed limits in hallicrafters design or construction there is always development change improvements many of the war adaptations were drawn from advanced developments that had been in the experimental stage for months for example in the pre war model plugging in a tuning unit might be quite attractive the holes in the proms couldn't get together or the new signal core transmitter guide channels made this tuning unit change quick positive and how the unit securely in place in the pre war model the proms on the tube were enough to hold it in place but this won't do the hopping shell holes the tubes support or a ring was added to lock that too firmly in position so that no amount of bumping or vibration would move it for stationary use no special footing was needed to anchor the transmitter but for rough riding in a truck rubber shockproof in the process of making the entire unit more rugged this air patter was replaced by a new vacuum tube padding condenser rooftop antennas could be as large as the pre war ham wanted to make them but it was pretty obvious that a regular such as this one would hardly do on the top of a signal corps truck the solution was in the use of whip antennas and in designing an antenna tuning unit which would throughout all of these changes to adapt a peacetime transmitter to wartime requirements the high quality standards of hallicrafters were strictly maintained in workmanship in design and construction and especially in performance when the signal corps inspected the first of hallicrafters transmitters armored for war they found what they were looking for a high powered unit that had been made completely mobile one that delivered good reliable performance under all conditions the first big job had been done well then came the warning of another bigger job field reports indicate performance of s c r to ninety nine accedes expectation requests to expedite production as much as possible and in working man's english that means let's go on production this is the plant in clearing illinois where mass production of the new s c r to ninety nine mobile radio station was obtained on a scale never dreamed  before in this industry the key man for this tremendous production jobs were selected from the ranks of the american radio amateurs these men had to know how the technical background and experience it took to get into action fast this entire operation is headed by herb hartley known to the amateur fraternity as w niamh w n g this production was accomplished through the splendid cooperation of hundreds of loyal skilled workers the real ised how big the job ahead was and knew how to do it c r two ninety nine and finally the very design and construction of the transmitter led itself to mass production better than any other pre war domestic transmit chassis was strong there was room to work with subassemblies this is the main assembly line from the end of which come the completed transmitters this is the feeder for the main assembly line here the subassemblies are inspected or hooked up to other components at the foot of the main assembly line the transmitter looks like this steel base t then the bleeder resistor which furnishes a constant load on the high voltage supply next the filter choke and condensers which supply direct current to the plate circuits of the transmitter in wiring these parts a great deal of time and work is saved by the use of pre formed cables the cables are cut formed and tipped already for installation and here's the basis embley completed in just a little more time than it's taken to show it meanwhile on the opposite side of the table the power control panel is being assembled these are the controls for filament voltage and modulator bias the purpose of this panel is to group within convenient reach of the operator of the essential power controls these cables here are cut to length and form over on the feeder table terminal lugs are soldered to the ns then all the other wires needed in the circuit are placed into position bound together so that soldering to terminals is the only operation needed in the final assembly this is a power panel cable when wiring is completed and the switches and fuses have been installed the sides are joined to the power control panel and this unit is ready to join the main assembly line the transmitter begins to take shape as the base is joined to the power panel unit electric oyster used for ease and accuracy and handling these parts now the main power transformer is set in place this is the unit that steps up the inputs to the hi voltage required to operate the final amplifier and modulator two after the transformer is connected the entire deck or base is forced into a dolly to make handling easier there is high power equipment on this deck and it's heavy the second deck contains the audio driver stage and modulator of the transmitter which makes possible radio telephone operation listen tire unit built in another plant has been inspected on the feeder tables and requires only a modulation transformer and a phone c w relay to be complete the top deck of the transmitter the radio frequency section begins with the installation of the cipher assembly which is fabricated at how the crafters twenty six st plants three separate tuning units may be plugged into this assembly