Inhaltsverzeichnis
RS-6 (Miniature Transceiver)
RS-6, developed with the technical assistance of the CIA and manufactured by Motorola.
With the technical assistance of the CIA, a miniature modular radio was developed around 1951/52; this set was used by agents, among others.
Technical data
- Frequency range: 2 x SW (3 - 7 / 7 - 16.5 MHz)
- Frequency display: Analogue dial
- Frequency memory: none
- Transmit power: 6 - 10 W
Power supply
- Mains operation: 70; 95; 120; 150; 190; 230; 270 V
- Batteries: 6.3 V
Dimensions
- RT-6 transmitter: 171 x 127 x 75 mm, weight 1.3 kg
- RR-6 receiver: 171 x 127 x 57 mm, weight 1.42 kg
- RP-6 power supply: 205 x 102 x 56 mm, weight 2.58 kg
- Filter Unit RA-6: 205 x 102 x 51 mm, weight 1.68 kg
Accessories
- Transmitting crystals
- Battery clamps
- Earphones
Operation
The small radio, often referred to as a „Spy Set“, consists of individual components that are interconnected: The receiver RR-6 is tunable in two frequency ranges, the transmitter is crystal-controlled, and the „Power Supply Unit“ RP-6 can be operated with numerous mains voltages occurring worldwide or with 6.3 V battery voltage. The „Filter Unit“ also houses the connecting cables between the individual modules.
The RP-6 power supply unit can be plugged into practically any socket worldwide thanks to its plug with a variable plug spacing that can be flexibly bent to fit. After the components have been assembled with the power supply unit switched off (OFF position), it is switched on and the rotary switch is turned step by step to the right, starting at the highest voltage, until the neon indicator starts to glow.
The power supply provides the necessary voltages 6.3 V (2.4 A) tube heaters and 90 / 400 V plate voltages for the receiver and transmitter tubes.
The RT-6 transmitter is crystal controlled. It has two frequency ranges, 3-7 and 7-16.5 MHz, corresponding to the blue and red range. The OSCILLATOR RANGE switch and the OSCILLATOR TUNING control are used to tune the oscillator, the corresponding blue or red band range must be observed. For the output stage, the FINAL RANGE SWITCH selects the band and the FINAL AMPLIFIER TUNING tunes the output stage.
To determine the frequency of the transmitter, a transmitting frequency crystal in the range 3-7 MHz is used; the set can also be tuned to the second or third harmonic. A vertical quarter-wave antenna is used; the length of the wire in feet is calculated from 234/frequency in MHz, in metres 0.238 x wavelength. In addition to the antenna, an earth connection must also be created.
To tune the transmitter, the transmitting quartz is inserted, the oscillator and output stage band switches are set to the appropriate band range. The oscillator and output stage tuning is now set near the operating frequency (red or blue numbers on the knurled wheels) and the set is switched to transmit mode using the TRANSMIT switch on the central filter unit RA-6. The antenna matching is now switched to TUNE so that the set does not emit any RF; now the transmit button is pressed and the final amplifier is tuned with FINAL AMPLIFIER TUNING control to maximum glow of the neon indicator lamp. Now the transmit button is pressed again and tuned with OSCILLATOR TUNING to maximum glow of the glow lamp. While holding down the transmit button, the antenna tuning control (ANT IMPEDANCE MATCHING) is now adjusted to maximise the ANT ADJ MAX neon indicator, and the final stage tuning may need some slight adjustment again.
The transmitter can be operated using the built-in fold-out morse key or an automatic Morse encoder (operating with with punched tape withz the message prerecorded).
The RR-6 receiver has a frequency coverage from 3 to 16.5 MHz on two bands, ‘red’ and ‘blue’, which are selected using the band switch RANGE. The tuning dial with the red and blue scale can be moved with the coarse tuning or the mechanically geared fine tuning VERNIER; to find a working frequency again at a later moment, the number can be noted on the log scale. The VOLUME control adjusts the audio output and the BFO control is used for single sideband reception; the receiver has a crystal calibrator to adjust the dial calibration every 500 kHz, at the MHz and half-MHz marks. The hairline on the frequency dial can be moved with ADJUST CALIBRATION when the calibration signal is tuned to ‘zero beat’ with the fine tuning control.
In transmit-receive mode, the operating switch on the RA-6 Filter Unit can be set to TRANSMIT. After the PTT button is released, the set immediately switches to receive mode using the antenna used for transmitting. In the RECVR position, the receiver can also be operated (also briefly press and release the transmit button to switch the transmit-receive relay), but then a separate receiving antenna must be connected to the ANT TERMinal on the receiver.
Technical principle
Receiver RR-6: The receiver is an eight-tube superheterodyne: the antenna signal is amplified in the RF preamplifier (V1: 5899]) and converted to the first IF of 455 kHz with the signal from the tunable or crystal-controlled (X1) oscillator (V2: 5899]) in the first mixer stage (V3: 5899]). After two IF stages (V4, V5, each 5899), the intermediate frequency of 455 kHz is demodulated (V6: 5718), and the audio signal is fed to the NF stage (V7: 5718). For CW or SSB reception, the BFO signal (V8: 5718) is added. The AF tube V7 is also used as a 500 kHz Pierce oscillator for the 500 kHz crystal calibrator.
Transmitter RT-6: The transmitter is a two-stage design. The oscillator (V101, 6AG5) oscillates as a quartz-controlled Pierce oscillator; the inhibiting grid voltage is switched on via the keying relay and the oscillator begins to oscillate. The signal is amplified in the RF output stage (V102, 2E26) and fed to the antenna via the antenna tuning network. Glow lamps indicate resonance in the oscillator and also in the power circuit.
RP-6 power supply: When operated from the mains, the voltage is processed by a mains transformer with numerous tappings for a wide range of operating voltages or, when operated from batteries, by a chopper and then rectified by the rectifier tube (V 201, 6X4).
Filter Unit RA-6: The filter unit stabilises the voltages and prepares the 6.3 V for the filament voltage and the plate voltages of 90 and 400 V for receiver and transmitter tubes, respectively. Two voltage stabilisers 5644 or 5787 are used here.
Components
Receiver RR-6: V1 (5899, RF); V2 (5899, OSCillator); V3(5899, MIXER); V4, V5, (each 5899, 1ST, 2ND IF); V6 (5718, DETektor); V7 (5718, AUDIO); V8(5718, BFO).
Transmitter RT-6: V101 (6AG5, OSC); V102 (2E26, RF FINAL)
Power Unit RP-6: V201 (6X4, RECT)
Filter Unit RA-6: V301 / V302 5644 or 5787.
