Fig.1(a) example Mode 1 application with remote power unit.
Fig.1(b) example Mode 1 application with local power unit and showing optional use of UHF preamplifier
and output splitter
Preamplifier Power Option
Line
-
power for a masthead or similar preamplifier is available at the UHF input in Mode 1. The
amplifier provides approximately 5V with a current rating of 30mA max., suitable for powering a
PRO
ception PROMHD11L or PROMHD11M preamplifier. If using other amplifiers, take care to
ensure that the current rating is not exceeded. Use a preamplifier only when the UHF input signals
would otherwise be too low in level—i.e. where the signal levels from the aerial are low, or where
there is an unusually long cable run between the aerial and the PROAMP310X amplifier. Always use
the minimum amount of preamplifier gain necessary to obtain satisfactory signal levels at the
amplifier input.
Preamplifier power is normally present at the UHF input, but will shut down if the aerial presents a
short
-
circuit at the input. Note that this shut
-
down is not self
-
resetting. If preamplifier power is
wanted, but has been shut
-
down by a temporary short circuit, it must be reset manually by
removing power to the amplifier for a few seconds. If necessary, preamplifier power can be
permanently disabled by means of an internal jumper (see
“
Advanced configuration features
”
on
page 7).
Additional UHF sources
Any additional UHF signal sources such as CCTV camera channels should be combined with the
aerial signal feed ahead of the PROAMP310X. This is done best using equipment providing a
buffered loop
-
through arrangement (e.g. the
PRO
ception PROMOD1
video and audio modulator) or
by the use of suitable combining filters. The practice of using wideband combiners is discouraged
since it can degrade signal
-
to
-
noise ratios and can cause locally generated signals to be radiated
from the aerial, possibly causing interference to other viewers.
Note:
where auxiliary equipment connected to the UHF input might be affected or jumper facility mentioned in
the previous section.
