tr switch

Posted on Feb 7, 2014

The project I present here is my attempt at a universal QRP T/R switch. The idea is to take care of the essentials, so that any QRP (i. e. , less than 10W) receiver *AND* CW transmitter can be connected, and work seamlessly. These are what I considered the `essentials` to be: The operational scenario would be as follows, and could easily be applied to any QRP

tr switch
Click here to download the full size of the above Circuit.

transmitter (or transceiver used as a transmitter) and any receiver (or transceiver used as a receiver). But the device is especially designed to accommodate a simple transmitter and receiver, each having few embellishments, and requiring none. Operationally, here`s how a typical case would work: When Steve Weber, KD1JV, used three 2N7000 power MosFETs in the final of his AT Sprint transceiver, and managed to produce 6 watts with same (4W at 20 Meters), it really opened my eyes to these little devices. I had always thought of these as audio or power-control devices, but now I began to think in a different direction. One thing that immediately occured to me is that these devices might be configured in such a manner as to provide an "on/off" switch to RF energy between the transmit line and the receiver`s antenna input. They could additionally provide protection to the receiver, by shunting any unwanted energy that might make it as far as the receiver`s antenna input. This led to some experimenting in SPICE, and eventually to the following essential T/R switch circuit: Let`s review the schematic. The transmit signal is tapped at the transmitter output - the transmitter remains connected to the antenna at all times - and arrives at the left "TX-ANT" port. Q1 serves to connect the receiver antenna port (right, "TO RX") to the antenna (during receive), or isolate it (during transmit). Because Q1 does not completely isolate the...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    sound generator
    In-Car Charger And Switcher Circuit For SLA Battery Circuit
    power inverter circuits
    Simple Twi-light using white LEDs
    Basics of Thyristors
    USB Cellphone Charger circuit
    Bicycle Rear-Light Afterglow Circuit
    Valve phono preamp build
    Bicycle speed circuit
    555 Rock lantern controller circuit diagram