Re: [time-nuts] eBay GPS antenna test.

Hi I think you probably will have to move up to around $500 or so (and still shop pretty hard) to find a Zephyr Geodetic 2 in excellent condition. A Novatel 703 Pinwheel would also be on the list of things to watch for. If you find a proper (L1 / L2 / L5 ) GNSS receiver with a pps out in

[time-nuts] eBay GPS antenna test.

It's still extremely rare to see a low-priced used triple-frequency antenna on ebay. For less than US$300 I've only spotted extremely beat-up Zephyr Geodetic Model 2s and a few Leica AX1203+ GNSS (only the "+GNSS" model is triple-frequency) (there is one up right now). I've seen at least one

Re: [time-nuts] eBay GPS antenna test.

Bob wrote: Hi Just so people don’t get to down on eBay antennas: I have gotten some deals on eBay I just couldn't have gotten elsewhere. That is a nice looking antenna. A bit pricey for my budget. I thought just north of $100 for a used Leica choke ring job was about it. The Trimble antenna I

Re: [time-nuts] eBay GPS antenna test.

e- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob > kb8tq > Sent: Tuesday, February 13, 2018 12:04 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] eBay GPS antenna test. > > Hi > > >> On Feb 13, 2

Re: [time-nuts] eBay GPS antenna test results.

Hi As with any antenna mods, the issue isn’t so much doing them as proving that what you did had this or that effect. A lot of what you are paying for on the fancy antennas is the fact that indeed they went through some sort of validation process on top of the design process. An equally valid

Re: [time-nuts] eBay GPS antenna test results.

On 2/15/18 6:04 AM, Bob kb8tq wrote: Hi There are a number of reasons to believe that these antennas are worse than the typical “telecom GPS” antenna for L1 only duty driving a TBolt. If you are going to do L1 / L2 work with something like a NetRS, then indeed you will need a dual band antenna.

Re: [time-nuts] eBay GPS antenna test results.

Hi There are a number of reasons to believe that these antennas are worse than the typical “telecom GPS” antenna for L1 only duty driving a TBolt. If you are going to do L1 / L2 work with something like a NetRS, then indeed you will need a dual band antenna. These (the $99 ones) are the lowest

Re: [time-nuts] eBay GPS antenna test.

: Tuesday, February 13, 2018 12:04 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] eBay GPS antenna test. Hi > On Feb 13, 2018, at 12:06 PM, Clint Jay <cjaysh...@gmail.com> wrote: > > Agreed but stock numbers on boxes and packets are

Re: [time-nuts] eBay GPS antenna test.

Hi > On Feb 13, 2018, at 12:06 PM, Clint Jay wrote: > > Agreed but stock numbers on boxes and packets are usually Arabic numerals > or a barcode. It's also possible the seller used a stock image which can be > copied and pasted into Google web search to track down the

Re: [time-nuts] eBay GPS antenna test.

Oh, and Google has a handy translation tool which does a reasonable job of translating Chinese text from a jpg image so that's also worth a try. On 13 Feb 2018 16:18, "Bob kb8tq" wrote: > Hi > > That can be a bit harder if the labels are all in Chinese. Maybe posting > pictures

Re: [time-nuts] eBay GPS antenna test.

Agreed but stock numbers on boxes and packets are usually Arabic numerals or a barcode. It's also possible the seller used a stock image which can be copied and pasted into Google web search to track down the maker or at least a distributor who has data. On 13 Feb 2018 16:18, "Bob kb8tq"

Re: [time-nuts] eBay GPS antenna test.

Hi That can be a bit harder if the labels are all in Chinese. Maybe posting pictures of the label? That way those (not I) who can read Chinese might spot something that allows a search to proceed. Bob > On Feb 13, 2018, at 11:06 AM, Clint Jay wrote: > > Sounds like a

Re: [time-nuts] eBay GPS antenna test.

Sounds like a drop shipping operation, they've found a supplier in China who is willing to send goods either in plain wrapping without any supplier name or the name of the agent who's selling it. It can be useful to Google anything that looks like a part number on the packaging, you'll often find

Re: [time-nuts] eBay GPS antenna test.

Hi China does a lot of things through a marketplace process. Lots of guys with piles of this or that. Any sort of product you get in (to them) small volume likely goes through this kind of arrangement. Buying OCXO’s and other timing gear is every bit as vulnerable to the “this one today,

[time-nuts] eBay GPS antenna test.

Bob wrote: Sitting here casually reading the data sheets for some of the modern Trimble survey receivers - they have gone to 7.2V (just below your 7.5V trigger point) as an antenna supply voltage. Who knows what that might imply relative to this antenna. After getting my refund, I sent the

Re: [time-nuts] eBay GPS antenna test results.

I would be extremely surprised if ebay does not rule in your favor. I've only had ONE case EVER opened against me, and it was CLEARLY not a valid case, but eBay still made me give the buyer his money back IN FULL to include shipping. eBay almost always picks the buyer over the seller. 73,

Re: [time-nuts] eBay GPS antenna test results.

Hi Sitting here casually reading the data sheets for some of the modern Trimble survey receivers - they have gone to 7.2V (just below your 7.5V trigger point) as an antenna supply voltage. Who knows what that might imply relative to this antenna. Bob > On Feb 11, 2018, at 12:44 PM, John

[time-nuts] eBay GPS antenna test results.

They have issued a refund. The seller said that my antenna was defective. This is kind of a strange outfit. They are in Russia selling Chinese goods, shipped from China. Since I don't have to return it, I will disassemble it to see what went bad. I replied that if he could assure me that it would

Re: [time-nuts] eBay GPS antenna test results.

Hi Well, good news / bad news I guess. The seller is at least responding to your input. They also did not come back with something about “there is no voltage spec”. It’s quite possible that they are the 5th person in a chain of sellers and a substitution got made (unknown to them) at seller 3.

[time-nuts] eBay GPS antenna test results.

I opened a "Not as listed" case and heard back from the seller. They said that the antenna is definitely 3.3 to 18 volts and have sold several that are in operation. They wanted to know specifically how I tested the antenna, why I thought it shorted, and if I actually ever hooked it to a GPS

Re: [time-nuts] eBay GPS antenna test results.

Hi Ok, the antenna in the pictures on the listing *does* have labeling in English and it sure looks like it says 3.3 to 18V on the antenna. Certainly you have (and the rest of us may soon have) a case for “not as shown” in terms of what you got (and we get). Bob > On Feb 9, 2018, at 9:31 PM,

[time-nuts] eBay GPS antenna test results.

Bob wrote: Is it labeled 3.3 to 18V on the antenna? No, the writing on the antenna is all Chinese. The specs published on eBay state that it is. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] eBay GPS antenna test results.

I would surmise that the antenna has (or rather had) a protection network to protect against voltage spikes or surges. Your description of events seems consistent with an triggered SCR crowbar circuit, and the 2nd attempt at the higher current limit shorted the SCR. Note that this may not have

Re: [time-nuts] eBay GPS antenna test results.

On 9 February 2018 at 21:43, John Green wrote: > To those who doubted that the antenna was actually a 3.3 to 18 volt design, > it seems you were correct. Today, I hooked it up to a variable power supply > and slowly raised the DC voltage fed to the antenna. It began to pull >

Re: [time-nuts] eBay GPS antenna test results.

Hi Is it labeled 3.3 to 18V on the antenna? Bob > On Feb 9, 2018, at 4:43 PM, John Green wrote: > > To those who doubted that the antenna was actually a 3.3 to 18 volt design, > it seems you were correct. Today, I hooked it up to a variable power supply > and slowly raised

Re: [time-nuts] eBay GPS antenna test results.

To those who doubted that the antenna was actually a 3.3 to 18 volt design, it seems you were correct. Today, I hooked it up to a variable power supply and slowly raised the DC voltage fed to the antenna. It began to pull current at about 2.9 volts and at 3.3 volts, took about 40 mA. I continued

Re: [time-nuts] eBay GPS antenna discussion.

Dr. David Kirkby wrote: Another RF engineer, who I don't know from working with antennas, said to me that antennas are a still a charlatan's paradise. Those words rang true to me. I have yet to see a yagi type antenna that, in practice actually produced the gain it was specified to produce. True,

Re: [time-nuts] eBay GPS antenna.

Please keep us informed I bought onBert Kehren Sent from my Galaxy Tab® A Original message From: John Green <wpxs...@gmail.com> Date: 2/6/18 4:03 PM (GMT-05:00) To: time-nuts@febo.com Subject: Re: [time-nuts] eBay GPS antenna. I kind of have to believe the specs. T

Re: [time-nuts] eBay GPS antenna.

Hi If you spend some “quality time” with the pictures in the listing, the antenna is indeed labeled “operating voltage 3.3 to 18V”. Yes, I find that a bit incredible. If there is nonsense being generated, it’s not by the person listing the antenna on eBay. My guess would be that the

Re: [time-nuts] eBay GPS antenna.

I kind of have to believe the specs. The two survey grade antennas I already have, a Leica and a Trimble, both have regulators in the preamp sections. The Leica has an 8 volt one and the Trimble has a 5 volt one. I intend to hook it up to a variable supply and watch the current as I increase

Re: [time-nuts] eBay GPS antenna.

On Tue, 6 Feb 2018 07:08:42 -0600 John Green wrote: > Thanks for the responses. It looks similar to but not exactly like the two > antennas referenced. They say the preamp is 3 to 5.5 volts, whereas the > eBay antenna says its preamp is good from 3.3 to 18 volts, indicating I

Re: [time-nuts] eBay GPS antenna.

It should work with a T bolt since its range is 3.3 to 18 volts. I also have a good bias T and GPS type splitter that only passes power to one port that I can also use. I hope the gain isn't a problem. I live in the country, so local RF shouldn't be an issue. I can scrounge up some pads if need

Re: [time-nuts] eBay GPS antenna.

Hi There is no need for something this exotic for L1 only reception. It *is* nice to have Glonass L1, but that’s about the extent of how fancy you need to go. As noted in another post, the preamp gain probably is pretty high on this antenna. That’s a standard that goes back to the early days

Re: [time-nuts] eBay GPS antenna.

Thanks for the responses. It looks similar to but not exactly like the two antennas referenced. They say the preamp is 3 to 5.5 volts, whereas the eBay antenna says its preamp is good from 3.3 to 18 volts, indicating I can run it off 12 volts. Regarding the internals, I must have somehow missed