Two schemes of connection of the transceiver to the sound card of the computer

The communication device of the computer sound card to the transceiver Wilfried Runoff (DO1SW) differs from many similar presence ARU (Fig.1). Input transformer 1:5 is the separation and protects your computer from static electricity and the potential difference between the PC and TRX.

Fig.1

Potentiometer R2 sets the required level of the bass signal output. Transistor VS (KT315) depending on the rotor position P1 and the signal level will be small within the shunt P2, working in this case as AGC to compensate for fluctuations in the input level.

Author: Wilfried Drain

Reinhard Krause-rechberg (DK5RK) also proposed a universal scheme interface to the microphone input of the transceiver. This interface is suitable for connection to all sound cards and for all modes, including SSTV (Fig.2) and does not require a separate supply voltage. Low frequency signal of the sound card is rectified by a voltage doubler on 2x1N4148 and opens a field-effect transistor BSN10A, which will only fit the self-locking type, preserving the high resistance state, the drain-source voltage without the gate.

Fig.2

With the appearance of the LF voltage it will switch, most of the transceivers are moving in the transfer mode already with a resistance of 1 Ohm, i.e. RTT-current is 1 mA. Used transistor has a direct channel 110 Ohm

Author: Reinhard Krause-rechberg (DK5RK); Publication: N. Bolshakov, rf.atnn.ru