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SS360 PTT output

SS360 PTT output

The accessories on the antenna line generally have an RF detection controlling a relay, if they must change of status during the transmission. An amplifier, an antenna pre-amplifier, a filter (MFJ 1026 for example) etc.

Some may also be controlled via an external PTT input. In this case, the transceiver must have a PTT output. It is a ground swiching which will thus directly command the internal switching of the accessory.

Here is a small modification of the Superstar 360 FM (or President Richard) to transform the CW socket into a PTT output. It does not require any printed circuit, only a few components placed on the weld side of the main card.


The schematic diagram

Superstar 360 - PTT OUT

Note that there is no galvanic insulation. This therefore supposes the grounds with the same potential. This assembly works perfectly with a B300*, a BV131* or an MFJ 1026 (receiving filter) for example.

*(B300 and BV131 have each been the subject of an article to add them an external PTT input).


Mounting of the components

Superstar 360 - PTT OUT

The aera shown opposite (welding side) is located on the left side, front towards you. It can be easily found.

The 2N7000 is first glued to the ground, its right spindle welded to the ground.

The diode comes to its left, anode to the ground and cathode connected to the drain from which leaves a wire which will be welded instead of the end of R304 (desoldered on one side to keep the possibility of reusing the CW transmit). This track goes to the CW socket which will thus become the PTT output.

From the central spindle, a 10 nF capacitor is connected to the mass to the left, a 33k resistor is connected to the ground to the right and finally, a 3k3 resistor is connected to the +8v tx track.

The second 10 nF capacitor comes in parallel to the jack "CW".

The verification consists in inserting a male jack plug on the CW socket and testing with the ohm-meter (or the continuity tester) between center pin and ground that we have only a few ohms when the device is transmitting.