Technical Specification - Racal Instruments RA-117 User Manual

3. Technical Specification
Frequency range:
Stability:
Input impedance:
Tuning:
Calibration:
Sensitivity:
Intermodulation:
Cross modulation:
Blocking:
Selectivity:
1 – 30 Mc/s
Afterwarm-up, overall drift is less than 50 c/s per hour
under conditions of constant supply voltage and ambient
temperature.
(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
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.
A 100 kc/s signal derived from a 1 Mc/s crystal oscillator
having an accuracy of 5 parts in 10
at 100 kc/s intervals.
A1 reception, bandwidth 3 Kc/s; 1 V for 18dB signal-to-
noise ratio. A2 reception, 30% modulated, bandwidth 3
Kc/s; 3 V for 18dB signal-to-noise ratio.
More than 100dB down for interfering signals at least
10% removed from the wanted signal.
For wanted signal levels between 3 V and 1mV, an inter-
fering 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.
With similar conditions to those for cross modulation an
unwanted signal must be 60dB greater before the audio
2
output of the wanted signal
blocking.
Six alternative I.F. bandwitchs are obtained by means of
a selector switch. Filter details are:
-6dB
(1) 13 kc/s
(2) 6.5 kc/s
(3) 3.0 kc/s
(4) 1.2 kc/s
(5) 0.3 kc/s
(6) 0.1 kc/s
[4]
6
provides check points
is reduced by 3dB due to
1
-66dB
35 kc/s
22 kc/s
15 kc/s
8 kc/s
Less than 2 kc/s
Less than 1.5 kc/s