DANIELS
ELECTRONICS LTD.
TM
VHF Enhanced Extra Wideband Receiver Instruction Manual IM10-VR3H040-AB
3-7
The other three COR outputs are all affected by the receiver's mute line, consequently, they only
become active when the Receiver is unsquelched.
• MOSFET Q5 provides an open drain output capable of sinking up to 2 amps when
active (unsquelched receiver) through main connector pins B12 / Z12. Jumpers JU26
and JU27 allow internal pull-up to 6.0 Vdc or +9.5 Vdc respectively. Power
MOSFET Q5 is rated for 60 Vdc maximum drain-to-source potential when in the off
state (squelched receiver).
• Opto-isolator U17 (optional) may be enabled by installing jumper JU28. U17 can
typically switch up to 100 mA of current while providing a high degree of electrical
isolation at main connector pins B18 / Z18.
• Optional relay RLY1 is enabled by installing jumper JU29 and installing RLY1.
RLY1 provides double pole, double throw connections at the main connector pins D2,
D6, D4, D8, D10, and D12.
3.1.11
Channel Selection
Synthesized receiver channel selection is achieved by setting a decimal number on four BCD
frequency select switches or by selecting one of 16 pre-programmed channels via the Channel
Select Lines. Seven backplane connections are used to communicate with the synthesizer unit.
Pins D28, D30, and D32 are used (in house) to program the synthesizer with up to 15 channels.
Channel Select Lines CSEL0 (LSB) through CSEL3 (MSB) are used once the synthesizer is
programmed to select one of 16 channels. If the Channel Select Lines are all low (channel 0) the
channel for the synthesizer is read from switches FSW1 (most significant) through FSW4 (least
significant) and the desired local oscillator frequency is generated; otherwise one of the 15 pre-
programmed frequencies is selected. The BCD switches can be changed at any time however
the low current synthesizer, due to the fact that it places itself in a sleep mode to conserve power,
will not change frequency unless the receiver power is cycled or the Channel Select lines are
changed. Since the resulting frequency is dependent on the receiver model, refer to the section
on frequency selection in the Receiver Manual or to the channel designation tables for that
particular receiver.
