Tektronix 491 - Section 1: Characteristics; Electrical Characteristics

INSTRUCTIONS : (Cont I d)
( )
( )
(
)
5. Slide the new shaft coupler @ over the Band A" oscillator dial
assembly drive shaft, put the extension shaft ~ into the shaft
coupler. @
6. Install half of the new flexible coupler @. on the shaft extension
@ and the other half on the Band "C" oscillator drive shaft.
7. Install the Band "C" oscillator* as follows:
* NOTE: Be sure the os ci ll a tor is turned to the high end (fully
clockwise) of the Band.
a)
b)
Align the two halves of the flexible coupler@ and insert the
center part of the flexible coupler.
Fasten the Band "C" oscillator in place with the 4-40 X .250 inch
screws
@·
( ) 8. Reconnect the band switch lever to the coupling rod @ on the dial
housing.
() 9. Align the Band "C" Oscillator as follows:
a. Temporarily reinstall the Tuning knob on the main dial drive shaft
and check for smooth operation of the Tuning knob.
b.
The Band "C" Oscillator rear support is fastened to the back end of
the Band "B" Osei ll a tor by a
1
u• shaped bracket. This bracket allows
mechanical
adjustment in two directions.
c. Side to Side adjustment is accomplished by loosening the set screw,
one on each side, and tightening the set screw on the other side.
D. TO REPLACE DIAL TAPE
( ) 1. Turn the Tuning di al** all the way to the high end, fully clockwise.
( ) 2. Remove the dial window mounting screws and remove the dial window.
( ) 3. Manually run
the dial tape off of the right hand spool, and pull the
tape off of the left hand spool.
( ) 4. Wind the new dial tape so the low end is on the outside. Thread
the dial tape onto the left hand spool and wind all of the tape on.
Then slip the high end over the right hand spool and turn until the
high end of the dial is in the center of the window, and reinstall
the di a 1 w i n dow.
**The collet on the Band "A" Oscillator and the set screws in the Band "C"
Oscillator shaft coupler should both be loose.
Page 5 of 9
050-0692- 0 2