Harmonics of the Transfer Oscillator are then compared in an in-
ternal mixer with the frequency to be measured, using the oscillo-
scope contained in the Transfer Oscillator to observe the difference
frequency. By suitable adjusting the Transfer Oscillator frequency,
a zero-beat can be obtained between a Transfer Oscillator harmonic
and any unknown frequency applied to the input. When the zero-beat
is obtained, the unknown frequency is determined merely by multi-
plying the reading on the frequency counter by the proper harmonic
number. I? the proper number is unknown, it can be found by simple
equation or the nomograph included in paragraph 2-3.
1-3 ACCURACY OF MEASUREMENT
The very high degree of setability, stability and the resolution of the
540A Transfer Oscillator are all such that the accuracy of the 524B
Electronic Counter is fully utilized over the greatly extended fre-
quency range. In practice very few r-f signals are stable enough
to be measured with such accuracy; thus the instability of the sig-
nal being measured becomes the greatest accuracy-limiting factor.
It is possible with the 540A Transfer Oscillator to read frequency
as close as 2 parts/lO million. For measurement of very stable,
noise-free c-w signals the accuracy of measurement approaches
1 part/million. When measuring pulsed r -f signals accuracy de-
pends to some extent upon the pulse length. Typical accuracies i
obtainable on a stable, pulsed carrier of 1000 megacycles are
approximately 3 parts/million for a 10 microsecond pulse and 10
parts/million for a 2. 5 microsecond pulse.
1-4 ACCESSORIES FURNISHED
The 540A Transfer Oscillator includes as part of the equipment,
two 6" coaxial-cable jumpers with BNC connectors for use between
jacks on the front panel, and one 4 ft. coaxial cable with BNC con-
nectors for connecting the Transfer Oscillator to external equip-
ment.
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