micro
HAM ©
2016
All rights reserved
ADVANCED DUAL RADIO (SO2R) CONFIGURATION
Setup requirements
This configuration expands on the basic SO2R configuration to support dual receive or in-band split using the
second RX input (“sub-receiver”) on both radios. Again, we use the same antenna farm and RF boxes as in the
first two examples. The additions are done in front of the Double Ten Switch as shown below.
Since “dual receive” is generally accomplished with stereo audio, this solution is based on a switching condition,
which disconnects antenna from one radio and connects both R ports of Double Ten Switch to the other radio for
dual receive, or diversity reception using separate antenna for each receiver. This solution is essentially a
combination of the first two examples. The necessary switching can be accomplished by using “steering” with a
safety reverse switch like the microHAM Four + Four 4+4 switch or two Top-Ten A/BSS switches. Using the
microHAM switch, one half of the 4+4 switch steers B port of the Double Ten switch between RX2 input of R1
and RX/TX port of R2 while the other half steers A port of the Double Ten switch between RX2 input of R2 and
RX/TX port of R1. Using this arrangement all necessary combinations of ports assignment are possible;
R1 RX/TX + R2 RX/TX, R1 RX/TX + R1 RX2, R2 RX/TX + R2 RX2 and R1 RX2 + R2 RX2. All assignments and
switching are done automatically simply by releasing the antenna path on one SMD and enabling RX antenna
split on the other SMD.
As with the conventional SO2R configuration,
SMD's local relay outputs need to be grouped
into two units - port A and port B. Port B will
be used to control Band Pass Filters for each
SMD. To add the second radio requires that
addition of a second SMD, BPF 1, BPF 2,
and PA 2 be added to the list of RF Boxes
and the Interconnections tab as shown on the
plan. Unused outputs on uLINK Relay 10,
ADR: 043 can be used in two units to control
the 4+4 switch.
SMD 2 will control PA 2 via its local PA port
the same way as SMD1 controls PA 1.
“Detach RX antenna on PTT”
is preferred if
“in-band” SO2R operation is desired and it is
possible that the receiving radio will be
connected to an antenna that is not RX safe.
If in band operation is not contemplated,
“
Prevent TX”
will provide the classic style of
“same band” lockout.
The Security tab frequency table needs to be
set the same as with conventional SO2R; each band must be listed separately since we want to be able to listen
on one radio while transmitting on the other.
Although the design of the 4+4 switch does not allow connecting the TX/RX port on one radio at the same time
as the RX2 port on the other radio, RX2 is not protected against RF generated by same radio on another band
because the protection strategy now considers each band separately. Many conflicts can be solved using Virtual
Exclusivity Switches as in the example. In any case, special care should be taken to measure the isolation in
all cases to be sure that there are no hazardous conflicts.
IMPORTANT:
If you are unsure about isolation between antennas and intend to use RX2 ports in your setup,
add Band Pass Filters for the RX2 ports of your radios!
125
