Specifications

4-3. TRANSMITTER FRONT PANEL ADJUSTMENTS.
NOTE:Prior to setting levels be sure transmitter is ON and set to proper frequency. See Section 3.
4-4. Level Adjustment (IF).
Determine the desired subcarrier level for your specific system. The 455 Transmitter subcarrier
level can be adjusted over the range of 75 mV to 300 mV p/p (approx. -8 TO -20 dB, 75Ω).
A. Level Adjustment Without Video or Other Channels.
If it is possible to set the subcarrier level with all other signals (i.e., video and all other subcarriers)
removed from the baseband, the desired subcarrier level may be set directly using an
oscilloscope or wideband AC voltmeter. If it is necessary to adjust the subcarrier level in a "live"
circuit with video and/or other subcarriers present, proceed to the method described in Paragraph
B., below; otherwise, proceed as follows:
1.Connect the BASEBAND INPUT BNC connector of the 455 Transmitter to a suitable
75Ω termination.
2.Connect the BASEBAND OUTPUT BNC connector of the 455 Transmitter to the
measuring instrument (either an oscilloscope or wideband AC voltmeter). If the measuring
instrument has a high impedance input (normally the case), this line should also be terminated
with a suitable 75Ω termination.
3.Adjust the IF (subcarrier level) screwdriver adjustment on the front panel for the
proper system level.
B. Level Adjustment With Video and/or Other Channels.
When other signals (such as video or other subcarrier channels) are present on the baseband,
it is necessary to use a measuring instrument that can be tuned to the desired signal (such as a
spectrum analyzer, frequency selective level meter, or modulation meter with level measuring
capability). Proceed as follows:
1.If the measuring instrument has a high impedance input, connect it to the baseband
signal at any convenient point after the insertion of the subcarrier to be adjusted. If the
455 Operation Manual Page 27 6/23/98