Hi Clay, Intersting subject. What design for ultra stable/clean power supply are you using please ? Thx, Gilles.
> On Sep 2, 2017, at 22:47, Clay Autery <[email protected]> wrote: > > PCTEL GPS-TMG-HR-26NCM Antenna. > http://www.neobits.com/pctel_maxrad_gps_tmg_hr_26ncm_high_rejection_gps_p2769137.htm > > Can't say what the gain tolerances are, but it appears to be a pretty > decent quality part. > > The distribution amp is an HP 58516A GPS L1 Distribution Amp with the > external power supply tap which will be fed with an ultras stable/clean > adjustable linear power supply. As I understand it, this is a unity > gain amp, so there should be little to no insertion loss or distro losses. > > The distribution amp will be mounted near the devices such that amp to > device jumpers will all be < 1 meter/3.28 feet. Likely a lot less. ALL > Times N-connectors until reaching a connector TM doesn't make. > > ______________________ > Clay Autery, KY5G > >> On 9/2/2017 3:26 PM, Bob kb8tq wrote: >> Hi >> >> A lot depends on what comes after the feed cable. The “disto amp” will >> determine >> a lot. You likely need 10 db of net gain in front of it to keep things >> running ok. For an >> antenna that is *really* 26 db (as opposed to 26 db +/- 6 db), that would >> come out to >> 16 db of feed line loss. This isn’t a terribly surprising outcome. The >> antennas are designed >> for installations that run 150’ or more of coax …. >> >> Bob >> >>> On Sep 2, 2017, at 2:57 PM, Clay Autery <[email protected]> wrote: >>> >>> Having decision-making problems for the materials for my GPS main >>> feedline. Going to use a TM LMR stock, just can't decide how big to go >>> with it... >>> >>> 26 dB 5vdc antenna on top of a 38 foot mast. Feed will come down the >>> inside/center of mast and exit near the bottom, thence routed through a >>> window and to the GPS distro amp. Antenna will feed GPSDO, NTP Server, >>> Blitzortung System Blue station, and one other device TBD. >>> >>> Just cannot decide how big to go with the antenna to distro amp feed... >>> Assuming 50 feet total (38' mast + 12 feet to amp in shack) @ 1800 MHz >>> (closest to 1725 MHz), here are the losses from just this piece >>> (ignoring the amp to device jumpers): >>> >>> -240 = 5.45 dB XXX - too much loss? >>> -400 = 2.85 dB >>> -500 = 2.30 dB XXX - too hard to find >>> -600 = 1.85 dB >>> -900 = 1.25 dB >>> >>> Money not necessarily a consideration as this is a short run for a >>> permanent installation. Don't anticipate ever moving the GPS antenna to >>> the tower. >>> For 900 and likely 600, likely would not be able to do it in one piece >>> as routing it out of the mast and into the shack would get complicated. >>> Would likely bring it out of the mast at the bottom with a right angle >>> connector, and then use a smaller diameter jumper for the last 12 feet. >>> 500 is pretty uncommon stock wise and it and connectors are harder to find. >>> >>> I already have the tooling for both 240 and 400... but I definitely >>> don't want to challenge ANY of the devices for signal gain. >>> >>> So it mostly boils down to easy vs. more effort ($$ aside).... Is it >>> worth the additional trouble to move from -400 to -600 or -900? To NOT >>> lose the 1-1.6 dB additional? >>> >>> I'd appreciate your recommendation and reasoning. Thanks in advance! >>> >>> 73, >>> >>> -- >>> ______________________ >>> Clay Autery, KY5G >>> MONTAC Enterprises >>> (318) 518-1389 > > _______________________________________________ > 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.
