Band Switch for SSB 6.1 transceiver

I have an idea about building band commutator for SSB 6.1 transceiver. The board supposed to be connected by 14 pin ribbon cable between main transceiver board and DDS board.

I added some blocking capacitors because I discovered some RF noise induced by ribbon cable. I assume it was coming from PICs conntrollers installed on DDS board.

The very cool feature of that board in ability to chain with another such board. Imagine, if you need to commutate +5V, +12V and +27V. You can stack 3 such boards and here you go. The current PCB desing is not for high-voltage commutation but relays can commutate about 1 kW of power up to 240V which is nice for their price. I don't recommend to use current PCB design in high-voltage (please, don't do that, it could be fatal) design.


SSB 6.1 RX/TX Board commutator

It has been drawn in KiCad v4.0.7.

There is nothing new from schematic design standpoint just a trivial switch.



This board uses cheap JQC-3F relays from China and scavenged 4126PL transistors from CFL lamp ballasts. Fairly speaking all NPN transistors wich could operate the relay current (Icollector≥100mA) will work fine here. It is simple commutator. You can even substitute those with N-channel mosfets, those will work fine too.



Use BD140 for Q1 because TX signal is coming inverted.

Install relays upsidedown. I recently found that they connect all lines to +12V by default. Looks like pin numbers on schematic didn't match actual connections in footprint.

Download band switch project ~170kB, zip.

Download KiCad

Bill of materials

C1, C2, C931 uF CUnpolarized capacitor
C3, C4, C5, C6, C7, C8, C10, C11, C129100 nF CUnpolarized capacitor
D1, D2, D3, D4, D5, D6, D77DDProtection Diode
J11Screw Terminal 01x02Screw Terminal 01x02Generic screw terminal, single row, 01x02
J21Screw Terminal 01x09Screw Terminal 01x09Generic screw terminal, single row, 01x09
J3, J42Conn 02x07 Odd Evenconn: Conn 02x07 Odd EvenGeneric connector, double row, 02x07, odd/even pin numbering scheme (row 1 odd numbers, row 2 even numbers)
J5, J6, J7, J84Conn 01x01conn: Conn 01x01Generic connector, single row, 01x01
K1, K2, K3, K4, K5, K6, K77JQC-3F(T73)relays: JQC-3F(T73)PCB Relay, +5V
Q11BD140 Q PNP BECTransistor PNP (general)
Q2, Q3, Q4, Q5, Q6, Q764126PL Q NPN BCETransistor NPN (general)
R1, R2, R3, R4, R5, R6, R13710 k RResistor
R7, R8, R9, R10, R11, R12, R1471 k RResistor

Checkout my design of SWR meter.


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