RA.366 PANORAMIC  ADAPTER

The maximum spectrum width that can be viewed is 1 MHz and this is selected by the MHz tuning control on the receiver.
When the Panoramic Adaptor is operated in the I.F. mode, spectrum analysis facilities are provided for signals in the I.F. passband of the receiver and are selected by using the kHz tuning control.
In either mode of operation the displayed spectrum can be expanded to permit finite inspection of the selected signal.

Signals appear on the screen of the CRT as inverted "V" deflections; the signal to which the receiver is tuned being seen as a deflection near the centre of the screen. Other signals within the selected spectrum appear to the left or right of centre according to their frequencies, and as the receiver is tuned these deflections will move across the CRT. When a deflection approaches the centre of the screen, its corresponding signal will be heard through the receiver.

A tuning marker signal is derived from the receiver when the adaptor is used in the R.F. mode and marker pips appear on the screen at 100 kHz intervals when the receiver is set to CAL.

There are two type of adaptor RA.366 and these differ only in the power supply unit which is available for the panoramic adaptor. The units are identified as follows:

• RA.366A (Drg. DA.40880/A) : without power supply unit.
  For use with RA.1217 having 10 mW audio output.
• RA.366B (Drg. DA.40880/B) : with power supply unit.
  For use with RA.217, RA.1218/RA.1220 and RA.1217 with 1 W audio output. The power unit used in the RA.366B is the PU.1153.

• R.F. Amplifier and 1st R.F. Mixer
  The output from the receiver (2-3 MHz input) is applied to the 2-3 MHz amplifier in the panoramic adaptor RA.366. The amplifier output is fed through a 2-3 MHz bandpass filter and is combined in the 1st r.f. mixer with 23-24 MHz from the sweep oscillator. The resultant frequency difference of 21 MHz is then applied to the 2nd r.f. mixer.

• 2nd R.F. Mixer and 19.4 MHz Crystal Oscillator
  The 21 MHz signal is combined with 19.4 MHz from the crystal oscillator in the 2nd r.f. mixer. The 1.6 MHz i.f. output from the 2nd r.f. mixer is passed through a low-pass filter to the i.f. module via the r.f. position of the r.f./i.f. selector switch.

• I.F. Module, 1.6 MHz Amplifier, and 1st I.F. Mixer
  The 1.6 MHz signal from the receiver is selected by the selector switch (r.f. position) on the front panel of the RA.366. In this mode, the 1.6 MHz signal is amplified and taken via a bandpass filter to the 1st i.f. mixer of the adaptor.
  In the "r.f." position of the selector, the mixer combines 1.145 MHz from the i.f. crystal oscillator with the 1.6 MHz signal to produce 455 kHz.
  In the "i.f." position, the r.f. section is switched out of the circuit and the 1st i.f. mixer then combines the 1.6 MHz signal from the receiver with the sweep oscillator output (1.145 MHz ±40 kHz) to produce 455 kHz. The 455 kHz signal is amplified and fed through the crystal filter.
  The amplified 455 kHz signal is taken via the diode detector to a vertical amplifier and the Y deflection plates of the CRT.

• Sawtooth generators
  The horizontal sawtooth generator receives a synchronising pulse from the i.f. sawtooth generator and produces a time base deflection voltage which is amplified by the horizontal deflection amplifier. The pulse is then fed to the horizontal deflection plates of the CRT. The horizontal sawtooth generator also supplies a synchronising pulse to the r.f. sawtooth generator to ensure that all three sawtooth generators are in synchronisation.

• Sweep Oscillator (23-24 MHz)
  The r.f. sawtooth generator provides a sawtooth voltage to the r.f. sweep oscillator at a sweep rate of 4 Hz. This sweep rate is set by an internal adjustment in the r.f. sawtooth generator. The oscillator sweeps from 23-24 MHz and is fed to the 1st r.f. mixer and the 1st marker mixer.

• Receiver Marker
  An output of 3.6-4.6 MHz is taken from the 2nd V.F.O. of the receiver and is fed, via a low pass filter, to the 1st marker mixer of the RA.366. A negative blanking pulse is also fed to the 1st marker mixer from a multivibrator which is triggered by the horizontal sawtooth generator. The mixer combines the 3.6-4.6 MHz with the 23-24 MHz output from the sweep oscillator to produce 19.4 MHz.

• 2nd Marker Mixer and Marker Generator
  The 19.4 MHz output from the 1st marker mixer is combined with 19.4 MHz from the r.f. crystal oscillator to produce a zero beat ±1 kHz output. This signal is amplified and fed to a multivibrator which produces a wide positive going square wave. The wide pulse width is necessary to prevent double pulsing of the marker generator by the audio signal on either side of zero beat.
  The multivibrator square wave output is integrated to obtain a positive spike which is used to trigger a third multivibrator. This multivibrator produces a positive square wave marker which is taken to the i.f. and detector module.
  The marker pulse and the detected signal are taken simultaneously to the Y deflection plates of the CRT.
  As the receiver is tuned (kHz), the receiver's 2nd V.F.O. frequency (3.6-4.6 MHz) varies the position of the marker pulse relative to the 23-24 MHz horizontal time base.

• Power unit (Internal D.C./D.C.)
  A D.C./D.C. inverter produces the e.h.t. voltages to operate the CRT.

• Racal Panoramic adapter RA-366     Operations & maintenance manual