|To:||Langwellen-Reflektor <[email protected]>|
|From:||"Hans-Albrecht Haffa" <[email protected]>|
|Date:||Mon, 30 Jan 2017 20:44:14 +0100|
kindly I ask You for ideas for a TRX swiching circuit with pin diodes for LF and MF. In the magazine "Funkamateur" 2/2017 an article of Donald Huff, W6JL ist published, using PIN-diodes 1N4007. A similar publication will find in the internet too from K9EW ("Boat Anchor QSK "). Both authors are using succdessfully rectifier diodes for 50 Hz as PIN Diodes for switching 1, 8 MHz until 30 MHz. Pin Diodes have a minimum usable frequency based on reverse recovery time of the diode, usually higher than 1 MHz.
I need `nt a full switching circuit, as I have a power output of the vac relais (Jennings dpdt (2 mal um), too slow for qsk) in receive path of abt -17 dbm in transmit mode, and I wish to a have an output of abt 30 uV (-77dbm) in receive path. A complete blocking of receive path ist not necessary, as I need a bit of TX-sig for having a sidetone in transmit mode. I use a "Line"(...what an old fashioned _expression_ for an not affordable equipment......). Solving the problem by muting the receiver, adding a side tone in an audio-postamplifier for the head phone means additional circuitry around about the receiver, what I want to avoid .
Your proposal? Any ideas welcome.
DK 8 ND
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