In a message dated 26/02/2008 03:39:11 GMT Standard Time, [email protected] writes:
Need recommendations for plans for an easily constructed homebrew 70cm mast mount preamp with built in RF sense TR switch (VOX controlled). I will not be running more than 50 watts in New Mexico or possibly 100 watts in CA when I move there. thanks and 73, Robert W6RQR
That's really tough Robert. Unless there is some sequencing going on inside your radio then any RF sensing circuit will mean that the relay contacts will be hot switched on transmit. A couple of seriesed limiting PIN diodes may help, but with 100W across them for a few 10s of milliseconds even that may not be enough to protect the Pre-amp.
On the preamp side, the design that was published in the journal in August (2006?) works well and has a noise figure of 0.5dB and is a no tune design. Details are on g0mrf.freeserve.co.uk
Thanks
David