User's Manual
UHF BI-DIRECTIONAL AMPLIFIER TECHNICAL MANUAL
8
Output Power Level – MSA#2 Setting
The preset level of the MSA#2 is Factory set with a 2 carrier input while monitoring IM products, such
that these IM products do not exceeding -13 dBm at the diplexer common port. This Factory set gives
the maximum operable power, therefore the unit must not be re-adjusted for giving higher output.
However, re-adjusting for lower output power is permitted, and the desired level could be easily obtained
with-in ±0.5dB of accuracy.
Since the PA unit has fixed gain, the output power could be settled to the desired level by mean of the
MSA#2 on the VGA unit. The MSA#2 attenuation can be set from 0 to 15dB per 1dB step, via a
hexadecimal switch (16 positions from “0” to “F”).
The output power re-setting must be done with the presence of the channel filters and diplexers in the
uplink and downlink paths. Since the VGA does have extra gain, a total insertion loss up 5dB on the
channel filter(s) still is acceptable, with no deterioration on the power level, nor the IM products.
Depending upon the carrier frequency and channel spacing, the maximum operable power can be varied
as shown below in Table II.
Table II: Max operable power ratings to
comply to FCC and Industry Canada specs.
(Diplexer loss not included)
COMPRODmodelnumber: UBDA3845
Frequencyband: 380‐445MHz●
DCsupplies: 5.4Volt/52Volt
Frequency
Range(MHz)
MaxOperablePowerRating(dBm)
CHSpace
6.25KHz
CHSpace
12.50KHz
CHSpace
25.00KHz
380‐400 27.00 31.50 32.00
401‐445 28.50 32.00 32.00
NOTE:the406.0‐406.1MHzwillnotbeincluded
COMPRODmodelnumber: UBDA4551
Frequencyband: 450‐512MHz
DCsupplies: 5.4Volt/52Volt
Frequency
Range(MHz)
MaxOperablePowerRating(dBm)
CHSpace
6.25KHz
CHSpace
12.50KHz
CHSpace
25.00KHz
450‐460 27.50 30.50 30.50
460‐490 27.50 31.00 33.00
490‐512 26.50 28.50 29.50