Holland Electronics HMA-860H - Manual (Page 5)

Installation Procedure
Adherence to these precautions will help prevent
problems during initial installation of the HMA-860H.
1. Connect the I.F. jumper from the I.F. output to the
I.F. input on the rear panel. Connect I.F. jumper
from the V.I.F. output to the V.I.F. input. Connect
I.F. jumper from the S.I.F. output to the S.I.F. input.
2. Connect the HMA-860H to a 1 00 - 240 VAC grounded
receptacle. Observe the lit LED light indicating
power is on.
3. Using a signal level meter or spectrum analyzer,
set the output level.
4. Check the aural carrier level. It should be set at 15
dBmv below the video carrier.
WARNING: When connecting the HMA-860H from the
rear panel “RF OUT” directly to a TV set,
attenuate the output sufficiently to prevent
overdriving the TV or use the -30dB front panel
test point for monitoring the modulator output.
5. Connect a 1.0 volt peak-to-peak video source to
the “VIDEO IN” on rear panel. Connect the
HMA-860H “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 proper combining
network.
Frequency Offsets
T
he federal Communications Commission
requires that cable system modulators which operate
in the aircraft communications and navigation bands
be offset in frequency by 12.5
/25.0 kHz. The HMA-860H
PLL oscillator is factory setto comply with FCC
requirements for frequency accuracy (+/- 5
kHz) in the
aeronautical communication and navigation bands.
FREQUENCY CHANNEL NUMBER OFFSET
120 to 138 MHz ---------------------- A,B,C --------------- 14,15,16 ----------- 12.5 KHz
108 to 120 MHz ---------------------- A-1, A-1 ------------ 99,98 --------------- 25 KHz
228 to 330 MHz ---------------------- L – EE--------------- 25-41 --------------- 12.5 KHz
330 to 336 MHz ---------------------- FF-------------------- 42 ------------------- 25 KHz
336 to 404 MHz ---------------------- GG-QQ ------------- 45-53 --------------- 12.5 KHz