Hi If the coax is real RG58 (as in solid poly core) you have 3-4 db of loss in it. If it's foam core, you have even less. The normal antennas have enough gain to easily handle 10 - 15 db of loss. A bigger concern than loss would be shielding. Depending on what's running around (moon bounce transmitters …), something like quad shield RG-6 might do better.
Bob On Nov 12, 2012, at 4:28 AM, Doug Parker <doug.par...@btinternet.com> wrote: > Hi Bob, > > Thanks for the thoughts, Chuck has provided the wisdom to solve my problem. > With GPSCon, my readings on the Z3801 are 'Signal Strength' and the Z3805A > are 'C/N' which are entirely different. I'd not noticed the change in > designation on the display. > > My antenna is a typical 'Base Station bullet' with an integral 20+dB preamp > and 15 feet of RG58 > > thanks > Doug > > > > > ________________________________ > From: Bob Camp <li...@rtty.us> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > Sent: Sunday, 11 November 2012, 20:52 > Subject: Re: [time-nuts] Z3805 hold-Over > > Hi > > You may well over drive the GPS board if you put more amplification in the > line. If the antenna and coax work ok with a 3801, they should be fine with a > 3805. If you have a very high gain setup, it may be ok for the 3801 and be > over driving the 3805 already. > > What kind of antenna and coax are you using? > > Bob > > On Nov 11, 2012, at 2:24 PM, Doug Parker <doug.par...@btinternet.com> wrote: > >> Hi John, >> >> Thanks for the observation, with the same antenna plugged into my Z3801, I >> get an SS of at least 90. >> >> I'll place a preamp in line to see if that increases the SS on the 3805 , >> maybe my problem is the GPS RX isn't well. Great point. >> >> Of course, I'll watch out for the 5V power feed going up the coax for the >> preamp in the antenna. >> >> 73s >> Doug >> G4DZU >> >> >> ________________________________ >> From: jmfranke <jmfra...@cox.net> >> To: Doug Parker <doug.par...@btinternet.com>; time-nuts@febo.com >> Sent: Sunday, 11 November 2012, 19:04 >> Subject: Re: [time-nuts] Z3805 hold-Over >> >> Your 21 ns for 1PPS and T1 does not look too bad, but the satellite received >> signal strengths are too low. You should have at least four or five SS >> values above 60-80. I always have at least three SS readings above 100. My >> Holdover runs between 03 and 4 microseconds. >> >> John WA4WDL >> >> -------------------------------------------------- >> From: "Doug Parker" <doug.par...@btinternet.com> >> Sent: Sunday, November 11, 2012 1:36 PM >> To: <time-nuts@febo.com> >> Subject: Re: [time-nuts] Z3805 hold-Over >> >>> >>> >>> >>> Hi, >>> >>> I've got a Z3805 from one of the Chineese sources and had problems with the >>> HP 11801 oscillator which came with it. Even after a couple of weeks >>> operartion it was moving vast EFC voltages with the 'Holdover Uncertainty >>> Predict' reaching a lowest of 19uS. >>> >>> So I tried the HP oscillator from my Z3801 in the Z3805 and the daily EFC >>> change is back to a resonable level, but after 5 days of settling down, the >>> 'Holdeover Uncertainy Predict' has only got down to 10uS.and is holding >>> about that value. >>> >>> Could some one please advise what figures they are getting. As there's >>> something sticking in my mind that the whole system should be lower than >>> 6.3uS after 3 days of locked operation. Or have I been dreaming..... >>> >>> I have attached a JPG of my GPSCon graph, hope it helps >>> >>> thanks & 73s >>> Doug >>> G4DZU >>> http://www.g4dzu.com/ >> >> >> >>> _______________________________________________ >>> 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. >> _______________________________________________ >> 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. > > > _______________________________________________ > 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. > _______________________________________________ > 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. _______________________________________________ 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.
