- 18 -
HD1 & HD2 - Antenna A and B Power - Activate/Disable
Jumpers
HD1
and
HD2
(both three pin headers) activate or disable power on the feedline to
INPUTs A and B.
HD1
is in the front corner of the circuit board directly behind the PHASE control and BAND
toggle switch. This header controls power to the INPUT A port. When this
jumper is on the middle and forward pins, power is OFF to INPUT port A as
shown. When this jumper is moved and connects the middle and rearmost pins,
power is applied to INPUT port A.
HD2
is along the edge of the board directly towards the rear from HD1. This header controls
power to INPUT port B. When this jumper is on the middle and forward pins,
power is OFF to INPUT port B as shown. When this jumper is moved and
connects the middle and rearmost pins, power is ON to INPUT port B.
Note:
During TX Mute activation, power to the active antennas is disabled
regardless of the Antenna Power jumper settings.
HD4 - Antenna Power Source
The
HD4
jumper determines the source of active antenna power, either through the
NCC-1
power supply or the
ANT PWR
jack on the rear panel. HD4 is a three pin header located at the
rear of the main circuit board near the power jacks and the two large power transistors that are
bolted to the main circuit board. When the jumper on HD4 is positioned on the middle and EXT
pins, antenna power comes from the
ANT PWR
jack. When the jumper on HD4
is positioned towards 12V, as shown, the antenna port power comes from the
NCC-1
main power supply.
HD5 - TX Mute Polarity
HD5
controls the logic state that activates the TX Mute polarity function and is located just
below the rear panel Ext Control connector. HD5 is a four pin header.
When
HD5 has two pin jumpers in both positions completely filling the header,
operation is normal.
A logic low activates the TX Mute. This means any
voltage above 3 volts positive or an open circuit allows the
NCC-1
to function normally. Power
is available for use at antenna ports.
Anything below 1 volt positive (including a "Ground on Transmit") causes the
NCC-1
to mute.
Power is removed from the antenna ports and the INPUT
A
port is connected directly to the
receiver port. Switching time is about 2 ms.
If one shunt on HD5 is installed on the center two header pins, logic is reversed.
Positive
voltage over 3 volts applied to the TX Mute will force the
NCC-1
into standby and
disable the antenna power feature. Any voltage below one volt, including a
grounded condition, will allow the unit to function normally.
