HP (Hewlett-Packard) HP 85660B ユーザーズマニュアル

This information is decoded by 

 and amplified by U5. The outputs of U5 are

approximatley 

 V when a band is valid and approximatley -22 V otherwise. These signals

are used to drive FET switches on the 

 Slope Generator and the 

 YTX Driver.

A second latch, 

 receives the same six lines a 

 but receives a different strobe, LCK5.

This strobe is valid when the six lines have preselector peaking information. The outputs
of this latch drive eight bits of a DAC which produces 0 to 10 V at the output of 
corresponding to DAC values of 0.00 to 63.75. This voltage goes to the 

 YTX Driver.

This circuit is used to adjust the tacking of the YTX when 

[

PRESELECTOR PEAK

) 

or 

 

 

 or 

 

 is keyed in.

U8 is a Quad D-Latch which is used to decode information relating to Hysteresis, Sample and
Hold, and Filter Capacitor information. Four lines from the 50-wire Instrument Bus go to the

 of the latch. The latch is strobed when these lines have valid RF Module information.

The instrument controller is able to connect the filter capacitor across the YTX, and control
the Hysteresis and Sample and Hold circuits on the YTX Driver.

U7 receives the -0.525 

 signal from the 

 YTX Driver, amplifies and offsets it

such that a 

 

z ramp centered about 6 V is produced at TP8. 

 to Q15 and

associated circuitry produce the offset for each band, and R2 varies the A-Band offset to
position the A-Band slope breakpoints.

The signal at TP8 has a maximum range on Band C (5.8 to 12.5 

 second harmonic)

of approximately 0 to 12 V. This signal is applied to two voltage dividers 

 and

 which drive the positive inputs to 

 and 

 respectively. The voltage at the

inputs to these op amps is clamped by CR5 and CR6 such that 

 sees only the first half

of the full band ramp and 

 sees only the second half. In this manner, each full band

is divided into two segments with one breakpoint in the center. Both 

 and 

 are

configured for a gain of 2 and an offset of approximately -6.2 V, for a 0 V output at 
and unity gain overall.

The outputs of U6 drive variable gain amplifiers as shown in Figure 1.

2