2-22
INSTALLATION ORBAN Model 8400
3. Calibrate the 4000’s Output level to the STL.
A) Press both TONE buttons on the 4000’s front panel.
B) Adjust the 4000’s Channel A and B OUT (Output) levels for 100% peak modula-
tion of the STL.
4. Calibrate the 4000’s Input level for normal operation using tone.
[Skip this step if you wish to calibrate the 4000’s Input level using program
material. (Refer to step 5 on page 2-23.)]
Some facilities have specific standards for transmission line-up. For
example,
a transmission standard may state that +4 dBu at 400Hz produces 50% modu-
lation of a microwave link. Or PPM6 might allow 8 dB of headroom so it
would modulate the link to 40%.
Determine the input level to the studio-to-transmitter link that produces 100%
modulation of the link.
In step 4-(D), you calibrate the gain of the 4000 below the threshold of limit-
ing.
For facilities using VU meters, we suggest:
100%
peak level (dBu) – 0VU level (dBu) – 14 dB = gain of the 4000
For example, with an STL where 100% modulation = +18 dBu, and with a
studio where 0VU = +4 dBu:
+18 − (+4) − 14 = set gain of the 4000 to 0 dB
For facilities using PPM meters, we suggest:
100% peak level (dBu) – PPM reference level (dBu) − 9 dB = gain of the
4000
For example, with an STL where 100% modulation = +15 dBu, and with a
studio where PPM reference level = +6 dBu:
+15 − (+6) − 9 = set gain of the 4000 to 0 dB
A)
Turn the IN (Input) control fully counterclockwise.
B) Press the OPERATE button, then the TEST button.
C) Apply a line-up tone to the 4000 input, at your organization’s standard reference
line-up level.
D) Calibrate the 4000 for the pre-determined gain or loss.
Measure the output level of the 4000 with an AC level meter. Adjust the
4000’s
IN control to achieve the desired gain or loss.
E)
Press the OPERATE button. Observe the LIMITING meter.
If no gain reduction is indicated, the standard line-up level is below thresh-
old.
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