6
Rev. 11/05
Ph: 800-421-6511
www.picomacom.com
Installation Procedures
Adherence to these precautions will help prevent problems during initial installation of the A860.
1.
Connect an I.F. jumper from the composite I.F. output to the composite I.F. input on the rear panel.
Connect an I.F. jumper from the video I.F. output to the video I.F. input on the rear panel.
Connect an I.F. jumper from the audio I.F. output to the audio I.F. input on the rear panel.
2.
Connect the
A860
to a 115 VAC grounded receptacle. Observe the front panel LEDs indicating the unit is active.
3.
Using a signal level meter or spectrum analyzer, set the output level to 60 dBmV.
4.
Check the aural carrier level. It should be set at 15 dBmV below the video carrier.
WARNING: When connecting the A860 directly to a TV set, attenuate the output sufficiently to prevent overdriving the TV.
The front panel test point is useful for monitoring modulator output.
5.
Connect a 1.0 volt peak-to-peak video source to the
“VIDEO IN”
on rear panel. Connect the
“RF OUT”
to a TV set, and compare
the contrast and brightness to a known signal (use off-air signal to insure a proper modulation level). If necessary, adjust the video
modulation until proper contrast is observed.
6.
Connect an audio source to the
“AUDIO IN”
on rear of the unit. Set audio modulation (peak deviation) to 25 kHz with the audio
modulation adjustment. A known off-air signal and a TV may be used to set adjustment for equal audio level.
7.
Connect the
“RF OUTPUT”
to a combining network.
FREQUENCY OFFSETS
The Federal Communications Commission requires that cable system modulators, which operate in the aircraft communications and
navigation bands, are offset in frequency by 12.5 kHz. The
A860
PLL oscillator is factory set to comply with FCC requirements for
frequency accuracy (±5 kHz) in the aeronautical communication and navigation bands.
FREQUENCY
CHANNEL
NUMBER
OFFSET
121.2625 – 137.7625 MHz
A,B,C
14,15,16
12.5 kHz
109.2750 – 119.7750 MHz
A-2, A-1
98, 99
25 kHz
229.2625 – 329.7625 MHz
L – EE
25 – 41
12.5 kHz
331.275 – 335.775 MHz
FF
42
25 kHz
337.2625 – 401.7625 MHz
GG – QQ
43 – 53
12.5 kHz
Harmonically Related Coherent (HRC) video carriers and Incrementally Related Coherent (IRC) video carriers are CATV channel
assignment methods to reduce the effect of beat products. The technique is used in expensive phase-locked headends where all units
are tied to a master 6.0003 MHz oscillator with a maximum error of 1 Hz.
A860
Installation
A860 Manual.qxd 11/21/05 10:34 AM Page 6
