GENERAL RADIO COMPANY 1263-8 Operating Instructions Manual page 20

TYPE 1263-B AMPLITUDE-REGULATING POWER SUPPLY
volt for the Type 1263-B Amplitude-Regulating Power Supply, and al-
though this is above the region usually considered to be square law for
the diode used in the Type 874-VR, quite noticeable reduction in the ef-
fect of harmonics can be obtained at output levels approaching this low
limit.
When the polarity of the response detector at the output of the de-
vice under test is the same as that of the diode in the output rectifier (neg-
ative peak rectifier), some apparent cancellation of the effect of har-
monics can take place. This is true where the phase of the harmonics
of the oscillator with respect to the fundamental has not been appreciably
altered in passing through the device under test. While this is not a
true elimination of the effects of the harmonics (since the device under
test is being measured for transmission of both fundamental and har-
monics by such an arrangement), the resulting display is often a truer
picture of the transmission characteristics than could be obtained with
nonmatching diode polarities. For this reason, the recommended matched
detector, Type 874-VQ, is supplied with a diode of the same type as is
used in the Type 874-VR.
5.3 RECTIFIER FREQUENCY CHARACTERISTICS.
The resonant frequency of the Type 874-VR Voltmeter Rectifier is
about 5400 Me. The actual output voltage ,is down from the indicated or
regulated level about 3 percent at 1000 Me and 13 percent at 2000 Me.
Figure 6 illustrates the frequency characteristics of the Type 874-VR
Voltmeter Rectifier or Type 874-VQ Voltmeter Detector with a typical
crystal diode. When the Type 874-VQ Voltmeter Detector is used as the
response detector, there is no need to apply a correction for frequency
response, since the errors in the Types 874-VR and 874-VQ cancel.
1.0
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<ll!J
!J
0
.9
0>
>
0
.J 1&.1 .
8
~~
~ ~
·1
~0
~
.6
r--
·5
0
RESONANT
-
----
i
----
--
...........
FREQUENCY 540C
Me.
............
-
r- ....
...
2
3
FREQUENCY- kMc
Figure 6. Resonance correction factors; Type 874- VR Voltmeter Rectifier.
15