Hi If you are doing your own antenna supply:
1) Make very sure it is current limited at some rational level (say 150 ma). A resettable fuse may be fine for this. 2) Make sure you have some way to detect a short on the antenna. 3) Put in some sort of surge suppression. A microwave compatible TVS at the antenna input is the best / first step. Some form of isolation to the main supply is a good second step. 4) At least rate everything so a 12V supply could be cobbled into the circuit. You never know when you might get a good deal on a high voltage antenna. 5) Unless you are only running mag mount “car” antennas, you need +5 / +3.3 selectable on the board. 6) If you have to do your own RF isolation / DC injection, design it as a bandpass (or at least a high pass) filter. The more energy you eliminate below 400 MHz, the less your TVS gets hit with in most cases. Lots of fun.. Bob > On Aug 5, 2016, at 10:51 AM, Nick Sayer via time-nuts <[email protected]> > wrote: > > In designing boards with the Venus838LPx-T module, I must supply external > antenna power myself. This is in contrast to the PA6H I’ve been using which > internally supplies 3.3v active antenna power (and measures it for loading to > switch between the internal and external antenna. The Venue module does not > have an internal antenna). > > I therefore have the opportunity to select between 3.3v and 5v power to feed > the external antenna. I could in principle do something more exotic, but I > can’t imagine another option that would be better. > > So far, 3.3v has worked with all of the antennae I’ve used, but the sample > size is two (four if you count active GPS splitters in the mix). > > In perusing the list, it sounds to me like modern antennae expect 3.3v, but I > thought I’d explicitly ask rather than assume. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
