[time-nuts] Chinese NTP Time server

Fri Dec 27 19:43:30 UTC 2019

No need for serial cable. Network port 4001 worked perfectly. It is 
documented in the Chinese Manual.
Thank you Google !

On 2019-12-27 14:12, Brian Lloyd wrote:
> On Fri, Dec 27, 2019 at 2:24 AM xaos <xaos at darksmile.net> wrote:
> 
>> Brian,
>> 
>> I created a new web  page with some pics and a live output of the NTP
>> server from "Lady Heather V5.0"
>> 
> 
> Nice. Did you interface LH using the serial output or through a network
> connection? I haven't run LH in about 6-7 years so I don't know its 
> current
> feature set. I haven't made a cable for the HD-15 connector.
> 
> 
>> 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 ...
>> 
> 
> Well, the parts came to around $10(us) from Mouser but I get your 
> point.
> They should be here today so I should be able to give you more info 
> tonight.
> 
>> 
>> 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.
>> 
> 
> The OCXO is powered by the +12V supply after passing through the input
> filter. The wall-wart switcher they provide is quite noisy, as one 
> would
> expect of a cheap wall-wart switcher. (Ripple and noise measuring about
> 60mV p-p with ripple and switching transients clearly visible.) 
> Measuring
> the noise at the input to the OCXO the noise is down to about 15mV, 
> mostly
> just HF noise, around 50-60MHz my 'scope says. Switching transients and
> ripple are gone. So it appears to me that they did spend some effort 
> trying
> to quiet down the noise at the power input.
> 
> And here I was worried what my next crazy project would be.
>> 
> 
> Heh.
> 
> 
>> 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.
>> >
>> >
>> 
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