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

The slope generator takes a voltage which is proportional to YTX frequency and produces a
current to control the slope attenuator in the 

 Last Converter, which compensates for

conversion loss variations of the input mixer within each frequency band. The slope generator
also has circuitry which decodes bandswitch and attenuator settings, produces pulses for
the sample and hold, and hysteresis circuits in the 

 YTX Driver, produces the YTX

peaking signal for the YTX Driver, and a signal to switch in the filter capacitor on the 
YTX Current Driver.

 is a hex latch which receives six lines from the 50-wire Instrument Bus and a strobe,

LCK2, which goes low when the six lines have valid A6 RF Module information. Three of
the latch outputs have attenuator setting information and go to the 

 Miscellaneous

Bias/Relay Driver. The other three lines have bandswitch information which is decoded by

 and 

 decodes the low band (Band A, 0 to 2.5 

and the external mixer band (Band F).

When pin 2 of 

 is high and pin 12 is low, Band A is selected. The output of 

 is high,

turning 

 on, bringing the collector of Q22 low. This turns 

 off, bringing the collector

of 

 (LO BAND) high. This information goes to the 

 Miscellaneous Bias/Relay

Driver to control the 

 RF input switch. Q20 inverts the signal and drives amplifier 

producing a signal which is approximately 

 V when Band A is valid and approximately

-8 V otherwise. This signal is used throughout the 

 Slope Generator. When pins 2 and

12 of 

 are both high, Band F is active. The output of 

 is low, turning 

 off, and

bringing the collector of 

 (and Band F line) high. At the same 

 

 turns on,

bringing the LO BAND line low.

 decoder is enabled when pin 2 of 

 is low. Pins 5 and 12 of 

 have coded information

giving harmonic numbers as shown in Table 1.

Table 1. Bandswitch Decoding

Band B2 (pin 12)   (pin 5)

N

B

0

1

1

C

0

2

D

1

1

3

E

0

0

4