[time-nuts] Chinese NTP Time server

[xaos]

Brian,

I created a new web  page with some pics and a live output of the NTP 
server from "Lady Heather V5.0"

https://www.maximaphysics.com/GPS.shtml

You can clearly see the Missing OP-AMP on the bottom of the unit in the pic.
You would think that these guys would add a penny part to this ...

The guy I bought it from has already agreed to have me sent it back. 
However, If you get yours working
I don't want to bother. Also, I wonder of my OCXO from a HP counter 
would fit in there. Prob needs lots of work.

And here I was worried what my next crazy project would be.

George, N2FGX

On 12/22/2019 12:49, Brian Lloyd wrote:
>
> On 11/26/19 09:28, xaos at darksmile.net wrote:
>> Hello everyone,
>>
>> Does anyone here know about this item:
>>
>> https://www.ebay.com/itm/Brand-New-NTP-Time-Server-GPSDO-GPS-Disciplined-Oscillator-GPS-Clock/362758051388?hash=item547610963c:g:yFIAAOSwgztdgfM9
>>
>>
>> George, N2FGX
> OK, I ordered one. I missed the part about the 10MHz output being
> "optional". (Optional? Really?) So I ordered one and it arrived 2 days
> ago. Delivery took about 3 weeks. Looks nice, well packed, no damage. It
> includes an active GPS antenna with about 20' of RG174 and a 12VDC
> wall-wart. Unit, antenna, and PSU, nothing else. No doc and no software.
> No problem ... so far.
>
> Plugged it in. Power supply LED comes on and the Sync LED is flashing at
> about 2Hz. About 20 seconds later the SV LED comes on. about 2 minutes
> later the Sync switches to 1Hz. I am guessing it has achieved some sort
> of lock. I connect the 10MHz output to my FA-2. Of course, no 10MHz
> output. (More on this later.) I plugged it into the network. Looked at
> my DHCP server. No IP address assigned. Huh. How do I find this thing on
> my network?
>
> eBay message back to the seller. Seller sends me a link to a zip file
> with the software and doc. The first 'uh oh' is that all the file names
> are in mandarin. I must admit, I find <mandarin>.pdf and <mandarin>.exe
> amusing. I have an old laptop that dual-boots Linux and Windows just for
> this sort of thing, i.e. annoying software that only runs on Windows. I
> extract everything from the zip file and try things out. One of the
> programs shows just an ip address of 192.168.0.100 and has three windows
> separated into dotted-quads. Could this be the tool that sets the IP
> address, subnet mask, and gateway? I run the PDF that opens with a
> picture of the unit through google translate. OK, yes, that is what the
> program does. There is a picture of the window and, guessing at the
> examples, I was right, IP addr, mask, and gateway. With 5 buttons to
> click on in varying orders, it tooks me several tries to finally get it
> to change its IP address to one on my network. It is now pingable.
>
> I look at some of the other programs. These are mostly in English, being
> open software, and do things like let you look at the status of the GPS
> receiver. After successfully setting the IP address of the unit, I was
> able to run the utility 'PowerGPS.exe' and have it report GPS status
> from the box.
>
> So I pointed ntp on my linux server at the box as a server. It synced
> right up and chose it as the primary ntp source. Clearly it works just
> peachy as an NTP server and is running in my network that way. Now to
> tackle the lack of 10MHz output.
>
> Opening up the box it clearly has a 10MHz OCXO so getting something out
> the 10MHz BNC connector should be fairly straight-forward. Examining the
> bottom of the board, the path from the OCXO to the 10MHz BNC output is
> pretty clear. It goes through a single buffer op-amp and then drives the
> BNC jack. The only problem is, the op-amp is missing. The pads are for
> an SO-8 package. Following the traces it is pretty clear it is a
> standard, single-op-amp pinout, i.e. :
>
>   1. n/c (null)
>   2. inverting input
>   3. non-inverting input
>   4. V-
>   5. n/c (null)
>   6. output
>   7. V+
>   8. n/c (null)
>
> Lots of parts could go there. Looks to me like it should probably be
> something like an LT1227. The op-amp is operated at a gain of 2 with a
> 100ohm FB resistor and 100ohm to ground. This should be pretty stable
> with 100ohm pretty much swamping any parasitic capacitance in the FB
> loop. The input is a 300 ohm/300ohm voltage divider so the overall gain
> of the stage is unity.
>
> Input to the buffer from the OCXO is capacitively-coupled as is the
> output. There is a 50ohm resistor in series with the output. The
> unloaded voltage output of the OCXO is a 3.5V positive square wave.
> After passing through the buffer it is probably supposed to approximate
> a 3V p-p sine wave. (At least, that is what the marketing verbiage
> suggests.)
>
> The board is already populated with linear +5v and -5v regulators (74L08
> and 74L09 respectively) and associated bypass/filtering. +5v is present
> at pin7. No -5v is present. Tracing the board back to the source of the
> -V at the input to the -5v regulator, one arrives at an empty 4-pin
> through-hole area marked u14. This has +7.5V on pin 2 which also feeds
> the input to the +5V regulator. Pin 3 is the -V output that feeds the
> input to the negative analog regulator. So the 64-dollar question is:
> does anyone know of a chip/module that is a 4-pin, 0.1" pin spacing,
> single-output, inverting regulator module, producing -7V from a +7V
> input? I need to find something like that to populate this board and get
> the 10MHz output. I haven't been able to find anything on Mouser or
> Digi-Key. I am guessing that this is something that already exists as a
> module but ...
>
> Yes, I have asked the seller about the parts to populate the board or
> the option of returning it and getting one already populated. If the
> seller tells me to go pound sand I would like to manage to make this
> work anyway.
>
> Hmm ... if I DC couple the input and run the op-amp with a single-ended
> +5v supply, it might work without the negative supply at all. My only
> worry would be latch-up because the input would be going right to the
> negative rail and approaching within 1.5V of the positive rail. OTOH,
> most op-amps now are pretty immune to latch-up. Just thinking aloud
> here. I am sure someone here has some ideas about getting this to work.
>
> Thanks in advance for humoring me.
>
>