Advance Instruments B4B, B4A, B4C, B4 Instruction Manual

TYPE B4

Including BtA, B4B, B4A/C and B4B/C

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SIGNAL G EN ER AT O R TY PE B 4

(Including fiM: B4B: B4A/C: B4B/C)

T h e Advance Type B4 Signal Generator is available in two versions,
the B4A and B4B, each providing a wide frequency range with accurate
frequency and output voltage calibration.

The frequency ranges are 100 kc/s to 80 Mc/s on B4A, and 30 kc/s to

30 Mc/s on B4B. The accuracy of frequency calibration is ± 1% A
linear scale and vernier are provided to give very close resetting accuracy.
Due to the use of a crystal voltmeter followed by our type A.38 high

frequency resistive attenuator, the output is measured to ± (1 dB + 2%
F.S.D.).

The signal can be modulated internally at 400 c/s from 0 to 80%. Ex

ternal modulation, also O to 80%, may be applied up to 30 kc/s into

the B4A and up to 10 kc/s into the B4B. Both internal and external

modulation depths are monitored.

The instruments are of robust construction and are simple to operate.

SPECIFICATION

FREQUENCY

Frequency ranges. .

B4A/C 100 kc/s to 80 Mc/s in 6 ranges. Accuracy ± 1 %

Range A
Range B
Range C

B4B/C 30 kc/s to 30 Mc/s in 6 ranges. Accuracy ± 1 %.

Range A
Range B
Range C

R.F. OUTPUT VOLTAGE Accuracy ± (1 dB + 2% F.S.D.).

100- 300 kc/s. Range D

300-1000 kc/s. Range E

1- 3 Mc/s. Range F

30- 100 kc/s. Range D

100- 300 kc/s. Range E

300-1000 kc/s. Range F

3-10 Mc/s.

10-30 Mc/s.

30-80 Mc/s.

1- 3 Mc/s.

3-10 Mc/s.

10-30 Mc/s.

The output voltage from the 75 ohm attenuator is fed into a
75 ohm transmission line which is terminated with a 75 ohm
dummy aerial pad. The output into 75 ohms is continuously

variable from l^V to lOOmV by means of a 4-step decade
attenuator and a continuously variable control. The signal is
monitored after the variable control to ensure accuracy at high
frequencies.

OUTPUT IMPEDANCE

The output impedance at the end of the unterminated trans
mission line is 75 ohms. When terminated by the Termination
Pad type TP1A supplied with the instrument, three impedance
values are available:—

(1) 37 ohms (with full output).
(2) 10 ohms (with one-tenth indicated output).
(3) A standard dummy aerial (with one-tenth indicated

INTERNAL MODULATION

output).

Frequency 400 c/s ± 10%
Modulation depth 0 to 80%; ± 1 dB ± 2% F.S.D.

EXTERNAL MODULATION

B4A 10 c/s to 30 kc/s, 0 to 80 % for frequencies less than l/30th

of the carrier frequency.

B4B 10 c/s to 10 kc/s, 0 to 80% for frequencies less than l/30th

of the carrier frequency.
Approximately 10% modulation depth per volt input into high
impedance is obtained. The modulation depth is monitored.

Accuracy ± 1 dB.