Sect. IV Page 3
within the fl db specifications for the instru- instrument will function within this accuracy
ment, a slight adjustment of the component when properly calibrated. Special equipment
replaced may bring the response back within and skill in using it are required for the cal-
tolerances. If it is impossible to adjust the ibration procedure. Unless both are available
network for satisfactory operation, return the it is recommended that the Model -hp- 207A
complete instrument to the factoryfor adjust- be sent to anauthorized repair station for this
ment. work.
4-8 LUBRICATION, TUNING-
Equipment Required
CAPACITOR DRIVE MECHANISM 1. Average-reading vacuum tube voltmeter
AND SWEEP POTENTIOMETER capable of read&g accurately down to at
Lubrication is recommended once or twice a least 20 cps such as a Hewlett-Packard Model
year, depending upon instrument useage. Oil 400D/H/L.
the frequency vernier knob shaft with light
machine oil. The sweep potentiometer gears 2. Alignment tool (insulated screwdriver).
may be lubricated with a light moly-grease
such as MOLUB-ALLOY #1 available from 3. A frequency-measuring device:
the Imperialoil andGrease Co., Los Angeles
48, California. a. Secondary frequency standard with
comparisonfacilities, such as a Hew-
4-9 CHECK FOR CAUSE OF DISTORTION lett-Packard Model lOOD Secondary Fre-
quency Standard. (If a larger scope pat-
General tern than provided by the Model lOOD is
To check for the cause of distortion, the d-c desired, an external oscilloscope may be
voltage between the cathodes of V3 and V4 used with the Model 100D.)
should be measured. There should be less
than 1 volt between the V3 - V4 cathodes. A or
20, 000 ohms-per- volt, or better voltmeter
(such as a Hewlett-Packard Model 41 OB), may b. Frequency counter such as a Hewlett
be used for making the measurements. Allow Packard Model 522B or 524B Elec-
a five minute warm-up period before making tronic Counter.
the voltage measurements. Connect one ter-
minal of the voltmeter to pin 3 of V3 and the
other to pin 3 of V4. Terminology
When the following -- expressions are used in
Bad Tube in Oscillator this text, they have the meaning here specified.
If more than 1 volt is measured between the
V3 - V4 cathodes, a bad tube in the oscillator Slip the dial: a. Remove center knob
is indicated. on frequency dial.
To determine which tube is not operating prop- b. Loosen four screws
erly; substitute another tube of corresponding which secure dial
RETMA standardcharacteristics for each tube plate to drive shaft.
in turn. After each tube substitution, measure
the distortion. Continue tube substitution un- c. Reset dial to position
til distortion in the output voltage is within the indicated in text.
rated 1%.
d. Tighten four securing
It is recommended that substitu- screws. (Center knob
tion be made first for V1 or V2 may be replaced at end of
since the characteristics of these procedure. )
tubes more greatlyaffect the pur-
ity of the output voltage than do On Calibration: Frequency indication cen-
the characteristics of V3 and V4. tered beneath dial indica-
tor index is the same as
output frequency.
4-1 0 CALIBRATION
Connections
The Model -hp- 207A is capable of generating Connection arrangements are indicatedin Fig-
frequencies with an accuracy of f40/b. The ure 4-1. Connect as follows: |
ACEC
