2-6
Service Guide 85309-90082
Operating Information
LO/IF Distribution Unit
85309B Rear Panel Features
85309B
power. The allowable input voltage range for this connector is 0 to -200 mV.
Test Mixers Connector Group
The three connectors in this group, J3 TEST 1 LO/IF (standard), J11 TEST 2 LO/IF (option 001 or 401), and
J13 TEST 3 LO/IF (option 002 or 402), are connected to the test mixers. A test mixer only requires one
connection. A diplexer allows the LO signal (which goes to the test mixer) and the IF signal (which comes
back from the test mixer) to travel over the same physical cable. This allows both signals to go through a
single-channel rotary joint.
J3 TEST 1 LO/IF (standard).
This port sends the local oscillator signal to the test mixer, and receives the IF
signal over the same connection. A diplexer inside the test mixer and the 85309B makes this possible.
The IF signal from the test mixer is amplified and sent to the receiver through J9 TEST 1 IF OUT.
J11 TEST 2 LO/IF (option 001).
This port operates the same as the TEST 1 LO/IF port. Option 001 or 401
adds a second test channel.
The IF signal from a second test mixer is amplified and sent to the receiver through J12 TEST 2 IF OUT.
J13 TEST 3 LO/IF (option 002).
This port operates the same as the TEST 1 LO/IF and TEST 2 LO/IF ports.
Options 002 or 402 adds a third test channel.
The IF signal from a third test mixer is amplified and sent to the receiver through J14 TEST 3 IF OUT.
LO Source Connector Group
The two connectors in this group, J1 LO INPUT and J6 POS Z BLANK, are connected to the LO source.
J1 LO INPUT.
Receives the local oscillator signal from the LO source. The 85309B distributes this to the test
and reference mixers.
J6 POS Z BLANK.
The LO source sends out the POS Z BLANK (TTL logic) signal during sweep retrace. POS Z
BLANK is monitored by the 85309B through this connector. The 85309B monitors this signal, and lowers the
gain in the automatic leveling control circuit during retrace. This keeps the gain of the ALC from peaking
during known power drops.
Receiver Connector Group
The four connectors in this group, J9 TEST 1 IF OUT (standard), J1O REFERENCE IF OUT, J12 TEST 2 IF OUT
(option 001 or 401), and J14 TEST 3 IF OUT (option 002 or 402), output the test and reference IF signals to the
receiver.
J9 TEST 1 IF OUT (standard).
This connector sends the test mixer's IF signal to the receiver. Generally, this
signal is connected, through the BNC-to-RECEIVER ADAPTER cable, to the receiver b2 input.
J1O REFERENCE IF OUT.
This connector sends the reference mixer's IF signal to the receiver. Generally, this
signal is connected, through the BNC-to-RECEIVER ADAPTER cable, to a1 on the receiver.
J12 TEST 2 IF OUT (option 001 or 401).
This connector sends the test mixer's IF signal to the receiver.
Generally, this signal is connected, through the BNC-to-RECEIVER ADAPTER cable, to the receiver b1 input.
J14 TEST 3 IF OUT (option 002 or 402).
This connector sends the test mixer's IF signal to the receiver.
Generally, this signal is connected, through the BNC-to-RECEIVER ADAPTER cable, to the receiver a2 input.
Summary of Contents for 85309B
Page 6: ...vi Service Guide 85309 90082...
Page 9: ...Service Guide 85309 90082 1 1 1 Getting Started...
Page 21: ...Service Guide 85309 90082 2 1 2 Operating Information...
Page 41: ...Service Guide 85309 90082 3 1 3 General Information...
Page 49: ...Service Guide 85309 90082 4 1 4 Service...
Page 76: ...4 28 Service Guide 85309 90082 Service LO IF Distribution Unit ReplaceableParts 85309B...