HP 206A - Recalibration; Lubrication of Tuning Capacitor Drive

Variable
resistor R39 for the
X1 range, variable capacitor C4 for
the
X10 range, and variable resistor R93 for the XlOO range are
used for centering the output level. First a reference is
set on the
X10 range with the FREQUENCY dial at 20. By means of capacitor
C4 the other end of the
X10 range is adjusted against the reference.
Then resistors R39 and R93 are adjusted as necessary to center the
change of output level versus frequency around the reference set on
the
X10 range. The following procedure may be used.
1.
Set the RANG^ switch at X10 and the FREQUENCY dial at 20,
to obtain a frequency of 200 cycles. Set the IMPEDANCE switch
at 600 and connect a 600-ohm load across the OUTPUT termi-
nals. Adjust the AMPLITUDE control to obtain an indication of
4 volts on the control panel voltmeter.
2.
Set the FREQUENCY dial at 200 on the X10 range, to obtain a
frequency of 2,000 cycles. Adjust capacitor C4 as necessary
to again obtain a 4-volt indication on the voltmeter.
3.
Using the level set at 20 on the
X10 range as a reference,ad-
just R39 and R93 on the X1 and Xl 00 ranges respectively to
center the change of output level versus frequency around the
reference, within approximately
+1 db.
4- 13 RECALIBRATION
If the Model 206A ever should need recalibration, write to the manu-
facturer for information or return the instrument to the factory for
recalibration. A reasonable charge will be made for this service.
4- 14
LUBRICATION OF TUNING CAPACITOR DRIVE ASSEMBLY
The tuning capacitor drive assembly should be lubricated once
a
month if the instrument is in constant use,
or every six months
if
the instrument has only occasional use. Before lubrication, all
dust and dirt that have collected on the tuning mechanism should
be removed. Lubricate the following:
1. Vernier drive shaft bearing, one drop.
2.
Idler pulley (below the pilot lamp socket), one drop.
3.
Spring loaded take -up
pulley (on the back of the FREQUENCY
dial tuning control
poarse] shaft), one drop next to casting.
The most satisfactory oil for this purpose is Lubriplate #3, manu-
factured by the Fiske Brothers Refining Co., Newark, New Jersey.