Lectrosonics QUADUHFD - Manual (Page 3)

Multi-channel Wireless System
GENERAL TECHNICAL DESCRIPTION
The QUADUHFD consists of three sub-systems; the housing which contains the gel-cell power supply, the UDM6
RF/power distribution module and the UDM6S RF distribution module.
The housing is constructed of machined aluminum. A strap handle is bolted directly to the top panel of the housing
for ease of carrying. The lead-acid gel-cell batteries are connected in series to provide 12 VDC (nominal) power to
all the modules installed into the system. These batteries were selected for their recharge characteristics and
reliability under extreme conditions. The batteries are also highly resistant to damage caused by prolonged deep
discharge.
The front end design places RF filtering before gain to minimize intermodulation (IM) products and prevent overload.
Two transmission line ceramic resonators at the input provide filtering with a 50 MHz bandwidth. Following the
resonators is a low noise, low gain RF amplifier designed to evenly compensate for splitter losses in the stage that
follows. A precision splitter/isolator divides the RF signal into four isolated signals, which prevents spurious RF
coupling between receivers. The splitter/isolator is also termination independent, which prevents mismatched or
disconnected RF outputs from affecting the other receivers.
Power can be supplied to the distribution module from four possible sources. The primary source is the gel-cell
battery pack built into the bottom of the housing. Secondly, power may also be provided through an external DC
power source of 12 to 16 VDC of either polarity. When an external source is connected, an internal relay automati­
cally disconnects the internal battery pack. If that DC source fails or is disconnected, the system automatically
reverts to the internal batteries. AC power can be provided through the charger included with the unit. While operat­
ing in the AC mode, the internal batteries are also recharged. All power circuits in the distirbution module are
independently protected by internal auto-reset fuses. If the power to one receiver fails, the other receivers will
continue to operate.
UDM6 Block Diagram
FRONT-END
CERAMIC
RESONATORS
ANTENNA
RF
AMP
SPLITTER
&
ISOLATOR
MAIN
CONTROL
SWITCH
5A
THERMAL
FUSE
EXTERNAL
12V DC
CH80
120V AC
CHARGING
CIRCUIT
AUTO
SWITCHING
RELAY
BUILT-IN
RECHARGEABLE
BATTERIES
750mA
THERMAL
FUSES
1
2
3
4
3
4
RF TO
RECEIVERS
12V DC
POWER TO
RECEIVERS
12V DC TO
UDM6S
DISTRIBUTION
MODULE
Rio Rancho, NM – USA 3