'RACALATOR' H.F. RECEIVER STABILIZER
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MA.210 'RACALATOR' H.F. RECEIVER STABILIZER |
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This is a unit which is not in my collection. All information presented here is taken from the RACAL publication brochure. |
The RACALATOR is designed for use with Racal RA.17L and RA.17C-12 receivers. It eliminates drift in the receiver second
v.f.o. controlling the mean variation of the tuned frequency within 1 to 2 Hz over long periods, with a control range
of +/- 1 kHz.
An electronic counter, using silicon integrated circuits almost exclusively, provides a precise indication
of the tuned frequency in units of 1 Hz.
A crystal-controlled frequency generator of very high stability is used as a reference source by the counter and the associated receiver.
An outstanding feature of the RACALATOR concept of frequency control is that the free tuning capability of the receiver is completely unimpaired and the operator is thus easily and quickly able to search or change frequency, locking to a new frequency when required.
The RACALATOR stabilizes the RA.17 receiver to present-day standards making it suitable for the reception of narrow-shift telegraphy and complex signals which require high orders of frequency stability and accuracy.
The RACALATOR is ruggedly constructed, using only high-grade materials and components, and is suitable for use with RA.17 receivers in operation throughout the world.
The RACALATOR operates as a frequency correcting control applied to the second variable frequency oscillator of the receiver. It is essentially in two parts: the frequency controller, and the frequency counter. The latter provides an in-line digital display with "nixie"-type tubes, which is latches to prevent flicker.
Three successive modes of operation are provided: "Coarse tune", "Fine tune", and "Hold"; each is associated with
one phase of the receiver tuning procedure. During the "Coarse tune" phase, the counterhas a recycling time of 0,11
seconds and displays the frequency within +/- 10 Hz.
In the "fine tune" condition, the counter recycles in 1,1 second and the display indicates in units of 1 Hz. When
switched to "Hold", the counter still recycles in 1,1 second, the last ("Hz. x 1") digit is extinguished, but can
be illuminated by press-button.
A front panel "centre-zero" meter gives an indication of correction voltage being applied to the receiver's oscillator. If the system falls out of lock, indication is given by a flashing light.
To tune the system to a required signal frequency the RACALATOR function switch is set to "Coarse tune", and tuning controls adjusted until the receiver is set within +/- 100 Hz. of the incoming signal as indicated on the RACALATOR display unit. The function switch is then set to "Fine tune" and a multi-turn control on the MA.210 front panel, which has an overall range of 500 Hz., is adjusted until the display indicates the desired frequency within +/- 1 Hz. On switching to "Hold", the RACALATOR starts the process of controlling the receiver second variable frequency oscillator to eliminate the effects of frequency drift. In this condition, the mean variation of receiver tuned frequency will not be more than 1-2 Hz. over very long periods of time.
A modification kit is available for modifying RA.17L and RA.17C-12 receivers for use with the RACALATOR.