TECHNICAL SPECIFICATION


RACAL Type RA117
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T E C H N I C A L S P E C I F I C A T I O N
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Frequency range: 1 - 30 Mc/s

Stability: Afterwarm-up, overall drift is less than 50 c/s per
hour under conditions of constant supply voltage and
ambient temperature.

Input impedance: (1) Wideband 2000-ohms approx.
(2) Wideband 75-ohms.
(3) 5 double-tuned circuits, 75 ohms.

(a) 1 - 2 Mc/s
(b) 2 - 4 Mc/s
(c) 4 - 8 Mc/s
(d) 8 - 16 Mc/s
(e) 16 - 30 Mc/s

Tuning: Effective scale lenght of approximately 145 feet,
i. e. 6 inches of scale lenght corresponds to 100 kc/s
Frequency increments remain constant over the entire
range.

Calibration: A 100 kc/s signal derived from a 1 Mc/s crystal
oscillator having an accuraty of 5 parts in 10/6
provides check points at 100 Kc/s intervals.

Sensitivity: A1 reception, bandwidth 3 Kc/s;
1µV for 18dB signal-to-noise ratio.
A2 reception, 30% modulated, bandwidth 3 Kc/s;
3µV for 18dB signal-to-noise ratio.

Intermodulation: More than 100dB down for interfering signals at
least 10% removed from the wanted signal.

Cross modulation: For wanted signal levels between 3µV and 1mV, an
interfering signal 10 Kc/s removed and modulated
30% must have a level greater than 50dB above that
of the wanted signal to produce a cross modulation
of 3%. The ratio of wanted to unwanted signal is
improved up to 10% off tune, at the rate of 3dB per
cent.

Blocking: With similar conditions to those for cross modulation
and unwanted signal f2 must be 60dB greater before
the audio output of the wanted signal f1 is reduced
by 3dB due to blocking.

Selectivity: Six alternative i.f. bandwitchs are obtained by
means of a selector switch. Filters detail are:

-6dB -66dB

(1) 13 kc/s 35 kc/s
(2) 6.5 kc/s 22 kc/s
(3) 3.0 kc/s 15 kc/s
(4) 1.2 kc/s 8 kc/s
(5) 0.3 kc/s Less than 2 kc/s
(6) 0.1 kc/s Less than 1.5 kc/s

Bandwidths 5 and 6 are obtained with crystal-lattice
filters; differences in centre frequencies of these
bandwitdth settings do not exceed 50c/s.

I.F. ouput: 100 kc/s at 75-ohms impedance. Level 0.2 V approx,
with a.v.c. in operation. Two outlets in parallel
are provided.

Image and spurious With wideband or tuned input, external image signals
responses: are at least 60dB down. Internally generated
spurious responses are less than 2dB above noise
level in all cases.

Noise factor: Better than 7dB troughout entire range.

B.F.O. range: ±8 kc/s

B.F.O. stability: With constant ambient temperature and supply
voltage, drift after warm-up does not exceed
50 c/s. For input level variations from 10µV
to 1mV, b.f.o. drift is negligible.

Automatic volyme An increase in signal level of 20dB above 1µV
control: improves the signal-to-noise ratio by 18dB. An
increase in signal level of 100dB above 1µV
increases the a.f. output by less than 7dB.

A.V.C. time constans: Short: Charge - 25 milliseconds.
Discharge - 200 milliseconds

Long: Charge - 200 milliseconds
Discharge - 1 second

A.F. response: With 13 kc/s bandwidth, response remains within
±4dB from 250 c/s to 600 c/s.

A.F. output: 1. 2½-in. loudspeaker on front panel (switched).
2. Two headphone sockets in parallel on front
panel. (see Note)
3. Three independent outputs of 3mW at 600-ohms
at rear of chassis.
4. One output of 10mW at 600-ohms. Preset level
is independent of A.F.GAIN control setting.
5. One output of 1W at 3-ohms.

Note: The two headphone sockets are connected
across one of the 600-ohms, 3mW outlets.

Distortion: Not greater than 5% at 1W output.

Hum level: With A.F.GAIN control at maximum, the hum level
is never worse than 40dB below rated output (1W)

Noise limiter: A series noise limiter circuit van be switched into
operation to provide limiting at modulation levels
exceeding 30%.

Meter indication: Alternative switching for indication of signal carrier
level, a.f. output level or "S" meter indication.

Power Supply: 100-125V and 200-250V, 45-65 c/s. Power consumption
100W approx.

Dimensions: Height Width Depth
For rack mounting 10½ 19 20.1/8 in.
(fitted dust cover) 26.7 48.25 51 cm.
Fitted cabinet 12 20.½ 21.7/8 in.
30.5 52 55.6 cm.

Weight:
Rack mounted 62 lb. (28 kg).
In cabinet 92 lb. (42 kg).


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