T/R Switch/LPF Adapter for PA

 T/R switch/LPF adapter bare PC Board for PA, w/four LPF module pcb’s – $12


 Four extra LPF module pcb’s – $4


Available later this summer


This through hole (2.70” x 1.68”) board allows you to interface a power amplifier to your low power transceiver. It incorporates an RF sensed T/R switch, optional input attenuator, and an output LPF for the amplifier. The LPF can be board mounted for a single band use or for multiple bands through the use of the included plug-in module pcbs. The T/R switch includes an active low for amplifier initiation, and has full QSK on slower CW speeds and semi-QSK for the medium to fast CW speeds; full QSK on SSB. The T/R relay specified is capable of handling 50 watts RF. The documentation has the component values for the band specific 160m-6m LPF. There’s a jumper to disable the amp for barefoot operation and another to manually select the TX enable line for adjusting the amplifier bias with no signal. It was designed to work with the QRPLabs 10W HF PA, but could be used with homebrewed or similar amplifiers. Antenna connections can be pcb mounted female BNC or SMA.  It’s an easy through hole project with readily available components.


Click here for circuit description and parts list


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