[time-nuts] Has anybody checked this? GPSDO in kit

Yep, I recently sorted through a bag of 100 crystals from China ($10, shipped) looking for a "good" one. They were ALL good... a complete waste of time. I was rather amazed at their consistency and performance for a 10 cent part. Last year I bought an alarm clock / game from China (looks

Re: [time-nuts] Has anybody checked this? GPSDO in kit

Hi The bigger issue with doing a “home brew” OCXO is getting crystals with known turn temperatures in a reasonable range for the project. Yes, you can build gear to do temperature runs on crystals and sort bags full of them. It’s likely that your whole bag of 5,000 came from the same bar and

Re: [time-nuts] Has anybody checked this? GPSDO in kit

On Sat, 22 Oct 2016 10:34:53 -0400 Tim Shoppa wrote: > I just went and visited their website, and see they also offer a "kit OCXO" > from mostly through-hole parts and PCB. The OCXO insulation box is made out > of PCB, the thermostat is simply a jellybean TO92 transistor, and

Re: [time-nuts] Has anybody checked this? GPSDO in kit

On 22 October 2016 at 17:22, Chris Albertson wrote: > > You have to remember what this thing replaces. In ham radio, some people > are using vacuum tube oscillators with mechanical variable capacitor > tuning. Maybe some advanced rigs use gear drive on the capacitor

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Hi The op amp has a PSRR of roughly 90 db at 1 Hz. As frequency goes up, the PSRR gets worse. What frequency is your “signal” at? A very normal 7912 fed by a normal supply will not produce a noticeable degradation in phase nose on the TBolt. Putting an un-filtered switcher on any of the lines

Re: [time-nuts] Has anybody checked this? GPSDO in kit

You need to catch up on what hams are REALLY using. On Saturday, October 22, 2016, Chris Albertson wrote: > > Unfortunately, it could be *lots* worse (like many orders of magnitude > > worse). It all depends on which parameter you > > are looking at and how much you

Re: [time-nuts] Anybody want a Thunderbolt power supply?

At this point, I have three prototype boards that are functional as far as I can tell. Unfortunately I don’t have a better reference which would allow me to make comparisons. If someone with a better reference could make a proper comparison, I’d be happy to send them a prototype. > On Oct

Re: [time-nuts] Anybody want a Thunderbolt power supply?

I think we are coming up to the noise floor here. We have identified a potential signal A from a 7912 (likely similar to a 7812, no guarentee). The remaining question is if you apply signal A to the power pin of a thunderbolt what is signal B added to the output. We know where we want signal B to

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Hi There is an *enormous* difference between regulation and it’s impact on stability (which is what this drifted off into) and PSRR and it’s impact on phase noise (which got lost at the tread moved on). PSRR does indeed matter, but a fairly simple linear regulator (or pair of cheap ones or coil

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Bob, this is good data and insights thanks for taking the time to share. Ultimately the question Nick is hoping to answer is what is the point of diminishing returns for voltage regulation. I think there are plenty of folks on this list that have shared data suggesting a switching regulator which

Re: [time-nuts] Has anybody checked this? GPSDO in kit

I just went and visited their website, and see they also offer a "kit OCXO" from mostly through-hole parts and PCB. The OCXO insulation box is made out of PCB, the thermostat is simply a jellybean TO92 transistor, and the 27MHz crystal is an AT-cut being operated around 45C, so nothing awful

Re: [time-nuts] Has anybody checked this? GPSDO in kit

> Unfortunately, it could be *lots* worse (like many orders of magnitude > worse). It all depends on which parameter you > are looking at and how much you want to add on to it. Phase noise and > second to second stability are two areas that > it is likely to have problems. > You have to remember

Re: [time-nuts] Has anybody checked this? GPSDO in kit

On Sat, Oct 22, 2016 at 7:02 AM, Giuseppe Marullo wrote: > > I just need a clean/self-calibrating 10MHz reference to tune HF radios > ...seems good enough for the price. > For HF this thing is more useful than a 10MHz reference because it can directly output any frequency

Re: [time-nuts] Has anybody checked this? GPSDO in kit

Hi > On Oct 22, 2016, at 10:02 AM, Giuseppe Marullo wrote: > > Hello, > > I know, I know it is not supposed to be high end stuff(timenutted), but I was > looking for a GPS clock and noticed that this could be a cheap GPSDO too: > > http://qrp-labs.com/progrock.html > >

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Hi The -12 V line is not the reference for the EFC. It *is* one supply into the op amp circuit that drives the EFC. Since the EFC is +/- 5V, there must be both a positive and a negative supply into the driver circuit for full output swing. The -12 can be anything between about -13 and -7

Re: [time-nuts] Anybody want a Thunderbolt power supply?

It all depends what the -12V rail is for, some have said it directly references the EFC dac. I would hope an ocxo would have a better tuning gain on its efc pin than supply pin but maybe that's not always true. On Saturday, 22 October 2016, Bob Camp wrote: > Hi > > The +12 goes

[time-nuts] Has anybody checked this? GPSDO in kit

Hello, I know, I know it is not supposed to be high end stuff(timenutted), but I was looking for a GPS clock and noticed that this could be a cheap GPSDO too: http://qrp-labs.com/progrock.html It has a OCXO option, a box, a display(customizable), a GPS and could be probably fitted with a

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Hi The +12 goes straight to the OCXO. All OCXO’s have a voltage sensitivity. That sensitivity is much higher than voltage sensitivity is much higher than what you see on the other two supply pins. Bob > On Oct 21, 2016, at 11:06 PM, Scott Stobbe wrote: > >

Re: [time-nuts] For those that insist on using switching power supplies

Am Thu, 13 Oct 2016 17:57:02 -0500 schrieb "Graham / KE9H" : > Actually, if they have the "CE" stamp on the product, then they have > very specific radio interference limits that they must test and meet. > It must have been tested, certified, and the certification package >