photo Collins AN/FRT-22 APPLICATION

The AN/FRT-22 40 kw Transmitter provides highly reliable radiotelegraph communication on long distance point-to-point circuits. A choice of CW, frequency shift keying or facsimile emission may be used in the 4.0 to 26.5 mc frequency range.


Either a crystal oscillator or a variable frequency oscillator may be used to control the transmitter output frequency. On-off keying is accomplished by control of the first buffer and first frequency multiplier bias in accordance with the keying impulses. The final amplifier utilizes a push pull grounded grid circuit with two groups of three type 3X2500A3 tubes. All variable-resonance circuits in the transmitter are servo positioned from the front panel. Tuning is automatic. Ten operating channels may be preset at any frequency within the transmitter range. Band switching is not required, since tuning is continuous over the entire range.

A special equipment rack is included in the intermediate power amplifier cabinet to provide mounting space for the following equipment: variable frequency stabilized master oscillator, 0-91/FRT-5; crystal controlled, RF oscillator, 0-270/FRT-26; frequency shift keyer, KY-45/FRT-5 and associated power supply PP-454/FRT-5. The rack swings out allowing access to the rear of all units. A coaxial input-patch panel provides selection of the desired input source.

The transmitter is housed in a four-section unified cabinet. Large glass windows allow visibility of all tubes. Meters associated with tuning or adjustments of the RF stages are mounted at eye level. DC control and status lamps are located below each window.

A primary line voltage regulating circuit maintains the primary input power at 230 volts with a line voltage variation of 10% and a frequency range of 50 to 60 cps. The high voltage plate tranformers are excluded.

Dimensions Transmitter - 91 9/16" H, 180 1/4" W, 59 7/16" D
IPA plate transformer - 60" H, 57" W, 30 1/2" D
PA plate transformer - 32" H, 42" W, 16" D
Weight (including transformers) 12,595 lbs
Frequency range 4.0 to 26.5 mc
Crystal type AN/CR-27/U, fundamental frequency between 2.0 and 4.2 mc
Types of emission A1 (on-off keying); F-1 (frequency shift keying); F-4 (facsimile frequency modulation); A-3a, A-3b or A-9c (single sideband reduced carrier, or composite transmissions) when used with external driving and modulating equipment
Keying speed Up to 400 wpm CW, or 240 dot-cycles per second FSK
Number of preset channels 10
Ambient humidity Up to 95%
Ambient temperature 32°F to 122°F
Power source requirements 230 volts ±10%, 50/60 cps, 3 phase, and 115 volts ±10%, 50/60 cps, 1 phase
Input power Filaments on, 11.2 kw; high voltage on with key up, 15.6 kw; key down with full power output, 84.5 kw
Power Factor 95% at normal operation
Carrier output CW or FSK, 40 kw; SSB, 30 kw peak envelope power
Output impedance A-1, F-1 or F-4 emission, 600 ohms, balanced with maximum SWR of 2:1; A-3a, A-3b or A-9c emission, 600 ohms balanced with maximum SWR of 1.5:1

RF stages AF stages and modulator Rectifiers
Number Type Number Type Number Type


ITU Country
ITU Country