Just use a standard attenuator between a pair of bias T's with their dc ports connected together.
Bruce > > On 02 April 2018 at 10:29 Azelio Boriani <[email protected]> wrote: > > An unusual attenuator with a DC pass. > > On Sun, Apr 1, 2018 at 10:21 PM, David C. Partridge > > <[email protected]> wrote: > > > > > > Or use a choke ring survey antenna and an attenuator :) > > > > Dave > > > > -----Original Message----- > > From: time-nuts [mailto:[email protected]] On Behalf Of > > Bob kb8tq > > Sent: 01 April 2018 14:43 > > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] GPS ANTENNA > > > > Hi > > > > Indeed, it is *very* easy to put to much gain in front of a timing > > GNSS receiver. These beasts are trying to dig out a signal that you can’t > > even see with a spectrum analyzer. > > It’s way to far below the noise floor to detect that way. They > > optimize things pretty tightly to get that done (and to hit a price target > > ….). Put to much gain in front of them and they get unhappy. > > > > Making this even more crazy, the survey industry standard antenna > > *does* have a lot of gain. Survey receivers need way more gain in front of > > them than timing receivers. Put a survey antenna directly on a timing > > device and trouble will likely be the outcome. Equally, a survey instrument > > probably will not be happy with a timing receiver. > > > > Why all this nonsense? As far as I can tell, it goes back to how > > the very early L1 / L2 survey boxes were designed back in the 1980’s and > > early 1990’s. They made a basic decision to put a lot of gain at the > > antenna. Motorola came along with their GPS modules later on. They made a > > *very* different decision about how to distribute the gain. There are very > > good arguments on both sides for why they did it this way. > > The bottom line is still - you need to match things up … > > > > Bob > > > > > > > > > > On Apr 1, 2018, at 2:36 AM, cfo <[email protected]> wrote: > > > > > > On Sat, 31 Mar 2018 10:58:19 -0500, > > > donandarline-Re5JQEeQqe8AvxtiuMwx3w > > > wrote: > > > > > > > > > > > > > > I found a supplier for high quality GPS antennas at a > > > > very reasonable > > > > price. PCTEL GPSL1-TMG-SPI-40NCB. > > > > > > > > > > > > > > *** SNIP *** > > > > > > I had one of those on 25m cable, and it worked fine on a > > > Tbolt , until > > > i got an active antenna splitter that also had some gain. > > > Then i had to replace it w. a 26dB version of same type, else > > > the > > > "Jackson Lite" was loosing sync. > > > > > > What i mean here, is that you can get too much gain too. > > > > > > Btw: Good price. > > > > > > CFO > > > Denmark > > > > > > _______________________________________________ > > > 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.
