2na1 (2on1) - Two transceivers to one
power amplifier - box
(S53CC, S51RM, S53WW and S53RM)
After successful WW CW contest expedition to Corsica
(TK0C M/S 2015), Boris – S53CC gave me a task to construct switching box, that allows
two transceivers alternately use one power amplifier with two antennas (»RUN«
antenna and »INBAND« antenna for S&P). Such switching box is replacement
for one power amplifier with some added functionalities.
At start we only have wide guess how much attenuation we
have between inband and run antennas, so some simulations and field
measurements were necessary. Robi – S53WW was a leader of that task and we
came to conclusion that 90dB of attenuation between RUN and INBAND ports on 2na1
box will be enough. We achieved 93dB on 28MHz. Robi has also wrote program for
PIC and helped to construct control board.
After it was decided to go TK0C M/2 in WW CW 2016 contest
(practically the same hardware as year before for M/S, with few additional
antennas) we decided to add PTT interlock for third transceiver with separate
power amplifier (MULT / second INBAND position). MULT is in fact band change station
seeking for mults or ordinary QSO's on other bands. Eight band changes are
allowed per hour for each of two positions in M/2 category. (RUN1 and RUN2.)
After 8 band changes are spent, MULT station can go to second INBAND position
with its own »mult« antenna and its own amplifier.
Functions of 2na1 box:
1) Handling PTT for 3 transceivers and one PA with interlock and switching
delays. This handling has two modes: simple interlock mode and »Ping-Pong mode«, interlock which prevent first and
second INBAND station to go TX one after another. That kills pile up on run
station.
2) Signaling at each transceiver witch position currently TXing. (We use
colour coded approach with table tennis balls illuminated with colour LED).
3) In case of only one TX antenna for band (in our setup it was 160 and 80)
2na1 box have to prevent transmitting on empty port automatically (with band
decoder) or manually.
4) Crossover function witch switch over INBAND and RUN antenna on TX and RX
simultaneously.
5) RX OUT and RX IN connectors on 2na1 box for implementing RX antenna switch
with additional RX filters and limiters. Using RX IN on transceivers is not
necessary any more.
Here are some
pictures:
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Here
is PDF of shematics and PCB
73 Sine - S53RM