By the way, this doesn't mean that the GA-27 is a poor antenna design, it's just not the best antenna choice for this situation.
The GA-27 is intended as an external antenna for Garmin's handheld receivers, which normally operate with passive patch or helix antennas. So the receiver itself needs to be sensitive enough to work well when an unamplified antenna is connected directly to the receiver, and the GA-27 preamp only needs to provide enough gain to overcome the losses in the cable plus a bit more. Additional gain could be detrimental in some circumstances (e.g. when placed near transmitting antennas on a vehicle), so the GA-27 might well be the best antenna for the Garmin handheld receivers. But a GPS board module is intended to be built into some piece of equipment, and probably expected to always be fed from a remote amplified antenna, never a local passive antenna. In those circumstances, it makes sense to put all the necessary gain at the antenna preamp and let the receiver be less sensitive. The manufacturer will recommend some antenna for use with the receiver, and though you don't usually have to use that particular antenna, it's probably a good idea for your antenna/cable/splitter setup to provide roughly the same signal level at the receiver. - Dave On Wed, Nov 2, 2011 at 01:19, David J Taylor <david-tay...@blueyonder.co.uk> wrote: >> I've made a small Web page describing what happened when I changed the >> puck antenna on a Rapco 1804M for a more sensitive one. The Rapco 1804M >> expects a big outside antenna. >> >> http://www.satsignal.eu/ntp/Rapco-1804M-notes.html > > This page has now been updated to provide a comparison between three puck > antennas - the Garmin GA 27 (BNC), a 3rd-party low-cost puck, and a Gilsson > puck antenna. It seems that the even higher signal level from the Gilsson > benefits the 1804M more than the other two. > > Cheers, > David > -- _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.