Re: [time-nuts] GPS Antenna Feed Line Decision

Hi > On Sep 5, 2017, at 5:19 PM, Charles Steinmetz wrote: > > Mike wrote: > >> I tried to see if there was any difference in the signal quality reported by >> Motorola UT+ and U-Blox Neo 6M (not timing grade but has a good 1PPS) over >> 30m of 2 different cable types.

Re: [time-nuts] GPS Antenna Feed Line Decision

Mike wrote: I tried to see if there was any difference in the signal quality reported by Motorola UT+ and U-Blox Neo 6M (not timing grade but has a good 1PPS) over 30m of 2 different cable types. I only had RG58(75 Ohm) and RG174(50 Ohm). RG58 is 50 ohm. RG59 is the "equivalent" 75-ohm

Re: [time-nuts] GPS Antenna Feed Line Decision

> Le 5 sept. 2017 à 16:17, Bob kb8tq a écrit : > > Hi > > > >> On Sep 5, 2017, at 6:06 AM, Hal Murray wrote: >> >> >> Clay Autery said: >>> I will use something better than RG-59 or RG-6 (even if it is only "better" >>> in my

Re: [time-nuts] GPS Antenna Feed Line Decision

Hi > On Sep 5, 2017, at 6:06 AM, Hal Murray wrote: > > > Clay Autery said: >> I will use something better than RG-59 or RG-6 (even if it is only "better" >> in my opinion). > > Crazy thought department. Can you also run a parallel run of RG-6

Re: [time-nuts] GPS Antenna Feed Line Decision

Clay Autery said: > I will use something better than RG-59 or RG-6 (even if it is only "better" > in my opinion). Crazy thought department. Can you also run a parallel run of RG-6 and run some tests to see if you can measure the difference? -- These are my opinions. I

Re: [time-nuts] GPS Antenna Feed Line Decision

I'm dating myself again but when I was employed at Hughes Aircraft we had an HP salesman dedicated to servicing just us.  So most everything came direct from them or Wiltron.  I liked traveling to HP events with him.  Hughes had a miserly expense reporting process.  His was, "I count the money

Re: [time-nuts] GPS Antenna Feed Line Decision

Hi A lot depends on just which outfit you buy your attenuators from. There certainly *are* outfits out there that supply you just over 20 db RL when the spec is 20. They also don’t charge very much for their attenuators …. Bob > On Sep 4, 2017, at 4:53 PM, jimlux wrote:

Re: [time-nuts] GPS Antenna Feed Line Decision

On 9/4/17 1:18 PM, Wes wrote: If these are COTS attenuators, their own return loss is unlikely to be 40 dB. In fact grabbing an old HP catalog off my bookshelf (I'm dating myself) I see a typical type N attenuator specified as 1.2 VSWR (~21 dB RL). I went on a quick "shopping" trip looking

Re: [time-nuts] GPS Antenna Feed Line Decision

Not being as nutty as many on this list I only skimmed the papers you provided.  Interesting and I will stand corrected regarding the use of 75 ohm cable in 50 ohm systems in critical situations.  In situations like my own, I'm not going to fuss about it. I realize this is NIST, the 1384

Re: [time-nuts] GPS Antenna Feed Line Decision

Although not time nuts related I believe this document speaks to some of the practical issues... http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-6297.pdf Mark Spencer m...@alignedsolutions.com > On Sep 3, 2017, at 4:56 PM, Mark Sims wrote: > > Real time nuts run

[time-nuts] GPS Antenna Feed Line Decision

Real time nuts run phase stable cable (some well over $50 / foot) in climate controlled ducts... which is all for nought unless you also climate control the antenna.Which is all standard practice for precision geodesy. Try to keep it all with a milli-Kelvin or two. Oh, and don't forget

Re: [time-nuts] GPS Antenna Feed Line Decision

Hi If you are running into a TBolt, it’s got an F connector and 75 ohm cable spec’d already …. The 50 ohm / 75 ohm thing didn’t seem to bother Trimble. They certainly looked at it before going that way …. Bob > On Sep 4, 2017, at 12:31 AM, Ian Stirling wrote: > > On

Re: [time-nuts] GPS Antenna Feed Line Decision

On 09/02/2017 02:57 PM, Clay Autery 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... I have a modest 26dB antenna on a six feet pole of plastic piping, the piping is strapped to my

Re: [time-nuts] GPS Antenna Feed Line Decision

On 9/3/17 3:41 PM, Charles Steinmetz wrote: Attila wrote: The supplies for LNAs are usually quite benign given two constraints: * * * 1) Low frequency (0Hz to bandwidth of signal) noise is low * * * But 1) is a bit harder as it also includes 1/f noise, temperature, (upstream)

Re: [time-nuts] GPS Antenna Feed Line Decision

I work with a broadcast station. We just had a HD FM radio transmitter upgrade done. In the upgrade package from GatesAir was a GPS antenna with a F fitting. The provided feedline was RG-223 with a TNC on one end and a SMA on the other. Also provided was a TNC to F adapter. The new exciter has

Re: [time-nuts] GPS Antenna Feed Line Decision

te <omni...@gmail.com> Sent: Saturday, September 2, 2017 9:33:09 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Antenna Feed Line Decision True, though a friend of mine used LMR-400. On Saturday, September 2, 2017, Mark Sims <hol...@hotmail.com>

Re: [time-nuts] GPS Antenna Feed Line Decision

Attila wrote: The supplies for LNAs are usually quite benign given two constraints: * * * 1) Low frequency (0Hz to bandwidth of signal) noise is low * * * But 1) is a bit harder as it also includes 1/f noise, temperature, (upstream) supply and load effects. The LT3042 is better

Re: [time-nuts] GPS Antenna Feed Line Decision

On 09/03/2017 06:02 PM, Bill Byrom wrote: For precision timing measurements, I would think that there would be concern about the double reflections of a badly mismatched low loss transmission line (such as using 75 ohm line in a 50 ohm environment). The re-reflected signal will act similar to

Re: [time-nuts] GPS Antenna Feed Line Decision

For precision timing measurements, I would think that there would be concern about the double reflections of a badly mismatched low loss transmission line (such as using 75 ohm line in a 50 ohm environment). The re-reflected signal will act similar to multipath (as a delayed aggressor) on all

Re: [time-nuts] GPS Antenna Feed Line Decision

On Sun, 3 Sep 2017 12:32:31 -0500 Clay Autery wrote: > - I saw in some aviation references where pilots claimed that they > achieved "better performance" by running their antennas at higher > voltages.  (Overclocking the antenna amp?  Who knows.)  But it piqued my > interest,

Re: [time-nuts] GPS Antenna Feed Line Decision

Hi. The last time I looked at upgrading my GPS antenna feed line (I'm currently using RG58 style cable) I spent some time looking at the temperature vs propagation delay characteristics of various cables. I also picked up a spool of cloned "LMR400 style" cable but ended up using that for my

Re: [time-nuts] GPS Antenna Feed Line Decision

Thank you for your response.  Again, money is not the issue or priority.  Knowing that I am getting the best signal within reason (my reason  ) Tangentially, you have provided me with the information I require.  As I do not know what I will hang off the end of that antenna in the future and I am

Re: [time-nuts] GPS Antenna Feed Line Decision

Actually haven't settled on an exact solution yet, Gilles.  The power supply will likely become part of the observations/experiment that prompted me to use the external supply in the first place. - All of the devices WANT to supply the antenna.  2 are nominal 5VDC, 1 supplies nominal 3.3VDC... 

Re: [time-nuts] GPS Antenna Feed Line Decision

Hi The bigger issue with unsuspended cables is wind and weather. It’s not just a static weight issue. When the wind blows the cable jerks around. You very much want to tie it off against the mast. You also want a strain relief loop at the antenna. Bob > On Sep 3, 2017, at 10:44 AM, Artek

Re: [time-nuts] GPS Antenna Feed Line Decision

Clay LMR-400 is probably the best compromise , I doubt you will see any useful improvement in system performance as a result of the improved 1.5db loss characteristics of the larger cables. Losses due to atmospherics, ionospherics and multi-path will be an orders of magnitude  higher than the

Re: [time-nuts] GPS Antenna Feed Line Decision

Hi There is no need to feed the 58516 or the antenna with any sort of super power supply. It’s just a simple RF amplifier in there. It’s designed to be feed off of the bias supply coming out of a GPS module. If a module has a dedicated 78L05 style regulator on it, it’s one of the better ones ….

Re: [time-nuts] GPS Antenna Feed Line Decision

On 9/2/2017 4:48 PM, Clay Autery wrote: Thanks for the response... Not sure why you and the other guy both recommended RG-6 75-Ohm cable and F-connectors, when the nominal impedance of literally everything else in the system is 50 Ohm, including the antenna and the HP GPS Distribution Amp 

Re: [time-nuts] GPS Antenna Feed Line Decision

On Sat, 2 Sep 2017 18:48:52 -0500 Clay Autery wrote: > Not sure why you and the other guy both recommended RG-6 75-Ohm cable > and F-connectors, when the nominal impedance of literally everything > else in the system is 50 Ohm, including the antenna and the HP GPS >

Re: [time-nuts] GPS Antenna Feed Line Decision

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 wrote: > > PCTEL GPS-TMG-HR-26NCM Antenna. >

Re: [time-nuts] GPS Antenna Feed Line Decision

Thanks for the response... Not sure why you and the other guy both recommended RG-6 75-Ohm cable and F-connectors, when the nominal impedance of literally everything else in the system is 50 Ohm, including the antenna and the HP GPS Distribution Amp  And then adding N to F adapters? Doesn't

Re: [time-nuts] GPS Antenna Feed Line Decision

HP 58516A GPS L1 Disribution Amplifier ( 4-way with external power supply input) __ Clay Autery, KY5G On 9/2/2017 3:38 PM, Pete Lancashire wrote: > What are you using for a distribution amplifier ? > > On Sat, Sep 2, 2017 at 11:57 AM, Clay Autery wrote: >

Re: [time-nuts] GPS Antenna Feed Line Decision

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

Re: [time-nuts] GPS Antenna Feed Line Decision

-Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Clay Autery Sent: Saturday, September 02, 2017 1:57 PM To: Time Nuts Subject: [time-nuts] GPS Antenna Feed Line Decision Having decision-making problems for the materials for my GPS main feedline.  Going to use a TM

Re: [time-nuts] GPS Antenna Feed Line Decision

True, though a friend of mine used LMR-400. On Saturday, September 2, 2017, Mark Sims wrote: > Cheap RG-59 cable coax is more than sufficient for 50 .. 150+ feet (unless > you are doing geodetic level GPS work). It is recommended by several GPSDO > makers. The 50/75 ohm

[time-nuts] GPS Antenna Feed Line Decision

Cheap RG-59 cable coax is more than sufficient for 50 .. 150+ feet (unless you are doing geodetic level GPS work). It is recommended by several GPSDO makers. The 50/75 ohm mismatch is not an issue. No need to waste money on fancy pants artisanal luxury coax.

Re: [time-nuts] GPS Antenna Feed Line Decision

Hi Modern distribution amp chips are likely to be sub 2 db NF. Gain is generally just a bit more than the loss through any post filtering and the passive power splitter after it. Bob > On Sep 2, 2017, at 7:02 PM, Wes wrote: > > This is just a cascaded noise figure

Re: [time-nuts] GPS Antenna Feed Line Decision

On 09/02/2017 02:57 PM, Clay Autery 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

Re: [time-nuts] GPS Antenna Feed Line Decision

This is just a cascaded noise figure situation. The first stage is the antenna (preamp) which has 26 dB gain (assumed) and an unknown noise figure. Assume it's a dB or so. Let the second stage gain be a negative value equal to the cable loss and the second stage noise figure be equal to the

Re: [time-nuts] GPS Antenna Feed Line Decision

What are you using for a distribution amplifier ? On Sat, Sep 2, 2017 at 11:57 AM, Clay Autery 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

Re: [time-nuts] GPS Antenna Feed Line Decision

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

[time-nuts] GPS Antenna Feed Line Decision

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