[time-nuts] eBay GPS antenna test.

Bob kb8tq kb8tq at n1k.org
Tue Feb 13 10:58:56 EST 2018


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, something 
different tomorrow” process that results. 

This sort of process is also vulnerable to the “grabbed the wrong box” problem.
The good ones are in this box and the others are in that box. I’m in a hurry 
and ….

It’s well worth remembering that we *are* (or should be)  paying a very low price 
for most of this stuff. It is unfortunate that paying a higher price does not 
seem to guarantee a better outcome. 


> On Feb 13, 2018, at 8:00 AM, John Green <wpxs472 at gmail.com> wrote:
> 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 seller a message saying that I would
> buy another if he could assure me it would work at 12 volts. He replied
> that he needed to get his hands on a couple and do some testing first. The
> antenna that I received seems to be different to the one pictured in the
> eBay listing. At least the labels are different. I get the feeling he is
> kind of a third party dealing with someone in China who is wholesaling
> antennas made by someone else. Who really knows what spec. these are made
> to, or by who. In my former place of employment, we made an SMB terminator.
> Basically, a 75 ohm resistor soldered across the pins of an SMB connector,
> then molded in black plastic. We bought the connectors from a Chinese
> supplier who supplied them in individual plastic bags. We had to cut the
> parts out of the bags before processing, which added a labor step. We tried
> to get the supplier to sell them to us packaged in bulk, but they refused.
> We decided that they were actually buying them from someone else and just
> doing a passthru. The connectors themselves would change from time to time,
> which caused problems in molding, and sometimes caused the electrical
> performance to degrade. Getting parts to reliably meet a specification from
> China can be a problem. I can't even imagine the issues that could arise
> when you try to source an assembly, or completed product.
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