Re: [time-nuts] MCXO and dual mode

Hi > On Jun 6, 2017, at 10:15 PM, Richard (Rick) Karlquist > wrote: > > > > On 6/6/2017 3:16 PM, Bob kb8tq wrote: >> Hi >> If you do the classic MCXO with two oscillator circuits and one resonator, >> the issue is >> pretty simple. You have a load capacitance on the

Re: [time-nuts] HP8640

Seems a bit sacrilegious no? Just kidding - wish I had another myself.. Brent KD4VMM On Tue, Jun 6, 2017 at 9:05 PM, KA2WEU--- via time-nuts wrote: > Hi , I am trying to find an well working HP 8640 to do some measurements > like SSB FM and AM noise. > > Who can help ?

[time-nuts] TruePosition --> Skyhook!

On February 19, 2014, TruePosition (a Liberty Media company) of Berwyn, PA bought Skyhook of Boston, MA. http://www.vcpost.com/articles/21778/20140220/us-wireless-location-firm-trueposition-buys-skyhook-wireless.htm Combining their expertise and experience, they are now operating under the

Re: [time-nuts] MCXO and dual mode

kb...@n1k.org said: > Let’s say both modes are running into a 32 pf load and it is a single > capacitor. I'm missing the big picture. Can I run both modes at the same time? Or do I switch between them? > The beat frequency shifts since the two modes do not tune identically. That sounds

Re: [time-nuts] TruePosition on the Arduino

Ben - I assume that you never received the Arduino "C code" written by Bruce, WA3YUE for the original project? Club's Powerpoint presentation indicated that source code was available. http://www.packratvhf.com/techinal.htm Packrat GPS Project (Gary, WA2OMY; Bruce, WA3YUE; George, KA3WXV) with

Re: [time-nuts] Poor man's oven

Hi The Freescale ADC’s are pretty good compared to a lot of other MCU ADC’s. They still are not as good as you might think from the audio ENOB numbers. Something in the 10~11 bit range is doing quite well at DC in a control loop, even for them. Bob > On Jun 6, 2017, at 8:12 PM, jimlux

Re: [time-nuts] Poor man's oven

You can feed in an external AREF, but look at the data sheet for the particular AVR chip. One thing which is commonly ignored in Arduino-Land is the I/O pin leakage current and the maximum source impedance specs. You are well advised to buffer the voltage you are reading, or make sure the

Re: [time-nuts] TruePosition on the Arduino

kb...@n1k.org said: > Calibrating your GPS pulse ambiguity is one of the all time great reasons to > get a WWVB based wall clock !!! What makes you so sure they won't have the same sort of next/previous bug? -- These are my opinions. I hate spam.

Re: [time-nuts] MCXO and dual mode

On 6/6/2017 3:16 PM, Bob kb8tq wrote: Hi If you do the classic MCXO with two oscillator circuits and one resonator, the issue is pretty simple. You have a load capacitance on the fundamental. You have a load capacitance on the third overtone. Even if it is the exact same capacitor, the

Re: [time-nuts] Poor man's oven

On Jun 6, 2017, at 7:10 PM, Chris Albertson wrote: There are more sophisticated control loop designs that can handle this better, eg by using two temperature sensors, one at the crystal and one at the heater. But designing them correctly is more difficult than

Re: [time-nuts] HP8640

Hi , I am trying to find an well working HP 8640 to do some measurements like SSB FM and AM noise. Who can help ? 73 de Ulrich N1UL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] HP8640

yes, I need it for about 1 day.. Thanks, Ulrich 1UL In a message dated 6/6/2017 9:37:35 P.M. Eastern Daylight Time, brent.ev...@gmail.com writes: Seems a bit sacrilegious no? Just kidding - wish I had another myself.. Brent KD4VMM On Tue, Jun 6, 2017 at 9:05 PM, KA2WEU--- via

Re: [time-nuts] Poor man's oven

Folks, with tongue firmly stuck in cheek, may I propose an old technique to stabilize xtal oscillators?You only need a "satellite" oscillator placed under your armpit... http://www.qsl.net/on7yd/136narro.htm#NihilNovum jon, ea2sn ___ time-nuts mailing

Re: [time-nuts] Poor man's oven

In message , Bob kb8tq writes: >In an OCXO design, the gotcha >is matching the PTC oven temperature to the crystal turn. You can do that if >you have a substantial inventory of material and custom fab the oven after >the crystal is built.

Re: [time-nuts] Poor man's oven

On 6/6/17 4:26 AM, Poul-Henning Kamp wrote: OCXO's have specified temperature ranges for instance -40...+70°C for the heavy duty stuff. But I cant imagine the ovens used are so perfect that they have the same regulation performance at all temperatures. I can choose the exterior

Re: [time-nuts] Poor man's oven

On Tue, 6 Jun 2017 05:52:56 -0700 jimlux wrote: > > Disregard aging of electronics and materials, we all know that > > stuff, what I'm interested in is at which exterior temperature > > OCXO ovens work best ? > > Here's my guess... > > 1) you want minimal gradients across

Re: [time-nuts] Poor man's oven

Chris, > The trick with using a uP and it's built-in A/D converters is scale. You > want the limited 10-bits of revolution to fall over the operating range > which is very narrow, like 1C. Anything outside of that is either or > and only seen at start-up., So at start up the the

Re: [time-nuts] Poor man's oven

On Tue, Jun 6, 2017 at 10:00 AM, Riley, Ian C CTR NSWC Philadelphia, 515 < ian.riley@navy.mil> wrote: > Is there a practical minimum for what voltage you can feed into AREF? > It is hard to find on the data sheet, but the minimum voltage for an Arduino's AREF is the internal analog reference

Re: [time-nuts] Poor man's oven

On Tue, 6 Jun 2017 11:00:57 -0700 Chris Albertson wrote: > > > > 1) You want the control loop as stable as possible > > 2) Stability is directly related to controllability > > 3) The larger the heat flow, the better the controllability > > 4) therefore the outside

[time-nuts] MCXO and dual mode (was: Poor man's oven)

On Mon, 5 Jun 2017 20:21:10 -0400 Bob kb8tq wrote: > That paper is the basis for the MCXO. It is an interesting way to do a TCXO. > The drift between the two modes makes it a difficult thing to master in an > OCXO. > Plating a pair of electrodes (one pair per mode) is also an

Re: [time-nuts] MCXO and dual mode (was: Poor man's oven)

Hi If you do the classic MCXO with two oscillator circuits and one resonator, the issue is pretty simple. You have a load capacitance on the fundamental. You have a load capacitance on the third overtone. Even if it is the exact same capacitor, the tuning sensitivity on the fundamental is

Re: [time-nuts] Poor man's oven

> There are more sophisticated control loop designs that can handle this > better, eg by using two temperature sensors, one at the crystal and > one at the heater. But designing them correctly is more difficult > than the normal PID loop. > Keeping with the thread topic, I think this is the key.

Re: [time-nuts] uC ADC resolution (was: Poor man's oven)

On Tue, Jun 6, 2017 at 2:17 PM, Attila Kinali wrote: > On Tue, 6 Jun 2017 16:37:27 -0400 > Bob kb8tq wrote: > > . Heck, the STM32F4xx have so much internal noise that the ENOB > of their ADC is below 6bit... so low that they even had to write an > appnote on

Re: [time-nuts] uC ADC resolution (was: Poor man's oven)

Hi You can only get back bits to the degree that the problems are caused by noise. If it is 1/F noise, averaging over long periods is going to be really tough. Bob > On Jun 6, 2017, at 7:43 PM, Chris Albertson wrote: > > On Tue, Jun 6, 2017 at 2:17 PM, Attila

Re: [time-nuts] Poor man's oven

Hi In the case of a second sensor, “at the crystal” effectively means “inside the crystal package”. That heads you into all sorts of “interesting” problems. Better to just read the papers and do it the “old fashioned” way. Bob > On Jun 6, 2017, at 7:10 PM, Chris Albertson

[time-nuts] TruePosition on the Arduino

Good evening all, There is a saying: "a man with one watch knows the time, a man with two is never sure." Clearly, this man wasn't a timenut and didn't have GPS. ;) I've been working on the Arduino code for the TruePosition boards that quite a few of us have bought from the e-place. It's

Re: [time-nuts] Poor man's oven

On 6/6/17 1:37 PM, Bob kb8tq wrote: Hi Often when you dig into the details of MCU ADC’s they have a little note “optimized for audio” or “not recommended for control loops”. It can be a bit of a head scratcher to work out what they are getting at. The big issues in this case seem to be DC

Re: [time-nuts] TruePosition on the Arduino

Ben: Be careful. Most GPS receivers send out the serial message after the tick, that tells you what the time of the tick was. Read the manual. If you want to drive a clock display with a GPS, you pretty much have to have an independent time system that advances on the tick, then validate it

Re: [time-nuts] TruePosition on the Arduino

Hi Calibrating your GPS pulse ambiguity is one of the all time great reasons to get a WWVB based wall clock !!! Bob > On Jun 6, 2017, at 8:38 PM, Graham / KE9H wrote: > > Ben: > > Be careful. > > Most GPS receivers send out the serial message after the tick, that

[time-nuts] Fwd: Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

https://www.febo.com/pipermail/time-nuts/2017-May/105566.html I said that thermistors have been obsolete for 40 years not themocouples. (With a FEW rare exceptions) I do not consider platinum wire to be a thermistor. I own a 100 Ω platinum wire thermometer for the DVM in my 2236 Tekronix. It

Re: [time-nuts] Poor man's oven

Hi For a while, a couple of outfits made TO-5 and TO-8 “cap heaters” with PTC material. There are still a few obscure places that people do the same sort of thing with a mini-pcb based design. In an OCXO design, the gotcha is matching the PTC oven temperature to the crystal turn. You can do that

Re: [time-nuts] Poor man's oven

The specs for the ADC are pretty vague : most of the errors are around 2 LSB but all are quoted with vref at 4V. If you reduce vref (there's an internal option of 1.1V) you'll increase gain but some of those errors are going to stay physically the same. In general, I'd tend expect to get more

Re: [time-nuts] Free to a good home: HP 100E Freq. Standard

I would love to have it, but I'm afraid I would need it shipped. What a great addition to my collection- no tube gear at all I'd be happy to pay the costs- I can send you funds once we figure out cost- if you are game. Shoot me an email off list and I'll provide shipping address.

Re: [time-nuts] Poor man's oven

Poul-Henning wrote: what I'm interested in is at which exterior temperature OCXO ovens work best ? Jim replied: Here's my guess... 1) you want minimal gradients across the device for a variety of reasons 2) therefore you want least amount of heat from the heater 3) therefore somewhat below

Re: [time-nuts] Poor man's oven

On Tue, Jun 6, 2017 at 7:34 AM, Attila Kinali wrote: > > 1) You want the control loop as stable as possible > 2) Stability is directly related to controllability > 3) The larger the heat flow, the better the controllability > 4) therefore the outside temperature should be as

Re: [time-nuts] Poor man's oven

Hi For a variety of reasons, if you go the MCU ADC route, put an op amp in between the thermistor bridge and the ADC. It takes care of a whole lot of issues. Bob > On Jun 6, 2017, at 12:13 PM, Adrian Godwin wrote: > > The specs for the ADC are pretty vague : most of the

Re: [time-nuts] Poor man's oven

Yes, as I wrote. I would not mess with AREF. At most you can only get a multiplication about 4. Use an op-amp. Signal conditioning really almost alway is required in the analog domain before any A/D conversion Also like the uP is not inside the oven and has a cable of some length so you'd

Re: [time-nuts] Poor man's oven

Hi As you point out, there really is no answer that is obviously better than all the others. If you keep the outside warm (say 40C) you will reduce the strain on the heater devices and likely not degrade the MTBF of anything outside the OCXO by very much. Bob > On Jun 6, 2017, at 7:26 AM,

Re: [time-nuts] Poor man's oven

On 6/6/2017 4:26 AM, Poul-Henning Kamp wrote: But I cant imagine the ovens used are so perfect that they have the same regulation performance at all temperatures. I can choose the exterior temperature, which I should prefer ? Disregard aging of electronics and materials, we all know that

Re: [time-nuts] Poor man's oven

csteinm...@yandex.com said: > It depends on what you mean by "best." "Best" can mean "minimizes the > wander in oven-regulated temperature at a constant (or slowly-changing) > ambient temperature," or it can mean "fastest recovery when the ambient > temperature changes more rapidly." I think

Re: [time-nuts] Poor man's oven

In message , Chris Albertson writes: >The next step up the complexity scale would have you place an I2C >interlaced ADC inside your oven. These don't cost much and have several >ADC channels. ISOtemp made a version of

Re: [time-nuts] Poor man's oven

On 6/6/17 11:47 AM, Chris Albertson wrote: Yes, as I wrote. I would not mess with AREF. At most you can only get a multiplication about 4. Use an op-amp. Signal conditioning really almost alway is required in the analog domain before any A/D conversion Also like the uP is not inside the

Re: [time-nuts] Poor man's oven

Hi Often when you dig into the details of MCU ADC’s they have a little note “optimized for audio” or “not recommended for control loops”. It can be a bit of a head scratcher to work out what they are getting at. The big issues in this case seem to be DC leakage and 1/F noise. Yes, they do

[time-nuts] uC ADC resolution (was: Poor man's oven)

On Tue, 6 Jun 2017 16:37:27 -0400 Bob kb8tq wrote: > Often when you dig into the details of MCU ADC’s they have a little note > “optimized for audio” or > “not recommended for control loops”. It can be a bit of a head scratcher to > work out what they are > getting at. The big