OK, lesson learned: check all conditions. The test system was feeding 3V rather than 5V to the antenna. Once the correct voltage is used, the characteristics make more sense. In fact, with a 25 ft. LMR-195 lead-in the VIC-100 gives almost unchanged SNR with 25dB attenuation added, -3dB with 30dB attenuation. The Timing 3000 shows -3dB change in SNR with 10 dB attenuation - quite a difference.
David At 10:23 PM 1/14/2009, you wrote: >Yes, more correctly I used 2 power inserters, one each way, to shunt >the antenna power around the attenuator so that the antenna is >powered and the GPS receiver sees the antenna as connected. > >David > >At 08:50 PM 1/14/2009, you wrote: > >And I did not make myself clear. > > > >If you were using power inserters, I expect one was used coming from > >your GPS receiver and you shunted the DC voltage around the attenuator > >and re-inserted DC voltage back to the antenna. > > > > > > > >Brian Kirby wrote: > > > Can we clarify, you were using the DC blocks or were they power > inserters ? > > > > > > Brian > > > > > > David McGaw wrote: > > >> Hello Gents (and Ladies), > > >> > > >> I am in a bit of a quandary. I have been using a Synergy Timing 3000 > > >> GPS antenna in a test set-up for some time and recently got a VIC-100 > > >> antenna, thinking that its greater spec-sheet gain (38dBi vs 25dB(i?) > > >> typical) would allow for a longer down-lead in the field if > > >> needed. Upon testing, the VIC-100 appears to have around 10dB LESS > > >> gain than the Timing 3000 and I would say is barely adequate on 25 ft > > >> of LMR-195! I used a switched attenuator pad with 2 DC blocks for > > >> the test and set each antenna to comparable SNR levels as indicated > > >> using TAC32 with an M12M-T. I have tried a second VIC-100 with the > > >> same results. Would anyone have an explanation for this? > > >> > > >> Thanks, > > >> > > >> David McGaw N1HAC > > >> > > >> > > >> > > >> _______________________________________________ > > >> 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. > > > > > > >_______________________________________________ > >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. _______________________________________________ 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.
