From philsemail at comcast.net Thu Oct 16 13:05:55 2014 From: philsemail at comcast.net (Phil) Date: Thu, 16 Oct 2014 10:05:55 -0700 Subject: [GPS_Standard] ocxo recommendations Message-ID: <543FFAF3.5010302@comcast.net> What ocxo's has the group used? (other than the HP unit) 73 Phil N6WKZ From dplatt at radagast.org Thu Oct 16 14:31:50 2014 From: dplatt at radagast.org (Dave Platt) Date: Thu, 16 Oct 2014 11:31:50 -0700 Subject: [GPS_Standard] ocxo recommendations In-Reply-To: <543FFAF3.5010302@comcast.net> References: <543FFAF3.5010302@comcast.net> Message-ID: <54400F16.5010306@radagast.org> On 10/16/2014 10:05 AM, Phil wrote: > What ocxo's has the group used? (other than the HP unit) I build mine around an Efratom 10 MHz VCOXCO. The one I bought was on a sub-board, mounted on a larger telecom board which generated a 15 MHz (I think) disciplined signal. There are a bunch of similar Efratom oscillators and boards available on eBay - I see at least two suppliers - see eBay auctions 280558808335 and 261327219062. The latter looks like a sub-board very similar to (perhaps identical to) the one I incorporated into my VE2ZAZ project. For $20 (delivered) it seems like a good candidate. They do have a disadvantage, compared to the HP - this oscillator family does not seem to provide a tightly- regulated 5-volt (or other) reference output for the control voltage. The VE2ZAZ design is such that the 5-volt supply to the PIC is effectively the reference for the control voltage, and a 7805 isn't the most stable voltage reference in the world... using a precision 5-volt regulator to drive the PIC would be a nice upgrade. I found that the temperature stability of mine wasn't as great as I had hoped - there was a perceptible shift in the control voltage over the course of a day, as the temperature in my garage drifted around. I improved things a lot by building a small temperature-controller-and-heater board, mounting it inside the project-box enclosure, and then insulating the whole box with foam - basically turning it from a single-oven to a double-oven architecture. This cut the control-voltage changes by about 50% and smoothed out the curve a lot, to the point where my modified (PI algorithm) control logic is keeping the tracking quite good. http://snulbug.mtview.ca.us/dave/fll.png The drift may have been my own fault, though. When I built my VE2ZAZ, I researched the Efratom oscillators and could not find any specific information about their voltage-supply requirements. I experimented, and found that mine seemed to heat up the oven and stabilize OK when powered from 12 volts, and I was afraid to drive it harder and perhaps burn it out, so that's what I gave it... I'm using a laptop-type 19-volt DC supply and regulating down to 12 volts. Both of the auctions now up on eBay show an input voltage of 24 volts. So, I may very well have been under-powering my oscillator's oven and making it harder for it to maintain the proper operating temperature. Maybe I'll dig up a 24-volt supply and rewire things a bit, and see if that improves the performance. From hwo at skynet.be Thu Oct 16 15:45:04 2014 From: hwo at skynet.be (ON4CDU) Date: Thu, 16 Oct 2014 21:45:04 +0200 Subject: [GPS_Standard] ocxo recommendations In-Reply-To: <543FFAF3.5010302@comcast.net> References: <543FFAF3.5010302@comcast.net> Message-ID: <005a01cfe979$ae826710$0b873530$@be> I am using the 10MHZ ISOTEMP OCXO 134-10 73, Hans, ON4CDU -----Oorspronkelijk bericht----- Van: GPS_Standard [mailto:gps_standard-bounces at mailman.qth.net] Namens Phil Verzonden: donderdag 16 oktober 2014 19:06 Aan: gps_standard at mailman.qth.net Onderwerp: [GPS_Standard] ocxo recommendations Urgentie: Hoog What ocxo's has the group used? (other than the HP unit) 73 Phil N6WKZ ______________________________________________________________ GPS_Standard mailing list Home: http://mailman.qth.net/mailman/listinfo/gps_standard Help: http://mailman.qth.net/mmfaq.htm Post: mailto:GPS_Standard at mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html --- Dit e-mailbericht bevat geen virussen en malware omdat avast! Antivirus-bescherming actief is. http://www.avast.com From philsemail at comcast.net Sat Oct 18 19:16:16 2014 From: philsemail at comcast.net (Phil) Date: Sat, 18 Oct 2014 16:16:16 -0700 Subject: [GPS_Standard] Frequency problem with LTC1485 chip Message-ID: <5442F4C0.3040006@comcast.net> Anyone ever have a problem with the LTC1485 (line driver) ? (U1) I just built the GPS Standard and I couldn't get a "lock". I started at the front end and I've got 10 MHZ going in and 10,000,230 (approx) coming out! I actually pulled the chip out and jumpered pin 6 to 1 (effectively bypassing the buffer chip) and got a brief lock. I'm new to the project.. any help would be appreciated! 73 Phil N6WKZ From mark.fancher at twc.com Sun Oct 19 15:15:23 2014 From: mark.fancher at twc.com (Mark Fancher) Date: Sun, 19 Oct 2014 15:15:23 -0400 Subject: [GPS_Standard] Board and Programmed Pic - Want to Purchase Message-ID: <000001cfebd1$08ac3730$1a04a590$@twc.com> Any suggestions? My HP oscillator and Oncore UT+ is on the way. Mark, AA4MF From dplatt at radagast.org Sun Oct 19 16:21:41 2014 From: dplatt at radagast.org (Dave Platt) Date: Sun, 19 Oct 2014 13:21:41 -0700 Subject: [GPS_Standard] Frequency problem with LTC1485 chip In-Reply-To: <5442F4C0.3040006@comcast.net> References: <5442F4C0.3040006@comcast.net> Message-ID: <54441D55.3080602@radagast.org> On 10/18/2014 04:16 PM, Phil wrote: > Anyone ever have a problem with the LTC1485 (line driver) ? (U1) > I just built the GPS Standard and I couldn't get a "lock". I started at > the front end and I've got 10 MHZ going in and 10,000,230 (approx) > coming out! > I actually pulled the chip out and jumpered pin 6 to 1 (effectively > bypassing the buffer chip) and got a brief lock. > I'm new to the project.. any help would be appreciated! I remember having real problems with the LTC1485 receiver when I used it on my board - no signal at all. The fix was simple once I figured out the cause. The LTC1485 and similar bus receivers are differential - they react to the relationship between their + and - inputs. In the VE2ZAZ design, one of these inputs is grounded... which means that for reliable operation, the other input must be pulled *below* ground. Many 10 MHz oscillators have CMOS- or TTL-compatible outputs, which do not swing below ground. This makes it difficult or impossible for the differential receiver to decode the signal properly. If the oscillator doesn't pull down below ground at all, there will be no output from the receiver (as happened to me). If the oscillator pulls down to right around ground, but there's some ringing on the signal (quite common) then you may get almost anything... including an output signal with occasional double-pulses, resulting in too high a frequency being detected (as might be happening in your case). There are two possible fixes: (1) Unground the grounded input to the LTC1485, and wire it to a reference voltage half-way between ground and the oscillator's peak output voltage. (2) Don't connect your oscillator directly to the LTC1485. Instead, couple it through a .1 uF capacitor, and install a medium-value resistor (4k7 or 10k or so) between the capacitor/LTC1485 junction, and ground. The latter is easier... you could do it either on the VE2ZAZ board, or at the oscillator, or in a wiring widget in between the two. The DC-blocking cap and the resistor will have the effect of shifting the oscillator's *average* voltage down to ground - the signal will swing between a couple of volts positive, and a couple of volts negative, at the LTC1485 input. This will allow the differential receiver to work reliably. From philsemail at comcast.net Tue Oct 21 12:45:46 2014 From: philsemail at comcast.net (Phil) Date: Tue, 21 Oct 2014 09:45:46 -0700 Subject: [GPS_Standard] GPS recommendations Message-ID: <54468DBA.40406@comcast.net> Can anyone recommend a GPS that is in current production? I've been using the SKM52, which Hans Summers sells for use with his Ultimate 3. It works well, but I need a 2nd unit and though that I would consult the group before my purchase. 73 Phil N6WKZ From pete.zl2ik at gmail.com Tue Oct 21 15:44:30 2014 From: pete.zl2ik at gmail.com (Peter Mulhare) Date: Wed, 22 Oct 2014 08:44:30 +1300 Subject: [GPS_Standard] GPS recommendations In-Reply-To: <54468DBA.40406@comcast.net> References: <54468DBA.40406@comcast.net> Message-ID: <5446b7a4.243d460a.5b54.2bb0@mx.google.com> Hi Phil Personally I would try an Adafruit "Ultimate GPS Breakout - 66 channel w/10 Hz Updates using the MTK3339 chipset - v3". They operate at 5V or 3.3V, have an onboard Voltage regulator and its logic is 5V friendly. I use one in my VE2ZAZ board. Works well and is extremely small. It will require a 3.3V external antenna if you mount it in a box however. Adafruit sell a suitable external antenna and a small coax tail which converts the on board GPS antenna connector to SMA, to fit the external Antenna termination. The GPS units are currently around $US40.00 each and can be purchased from retailers or of eBay. Pete Mulhare ZL2iK -----Original Message----- From: GPS_Standard [mailto:gps_standard-bounces at mailman.qth .net] On Behalf Of Phil Sent: 22 October 2014 5:46 a.m. To: gps_standard at mailman.qth.net Subject: [GPS_Standard] GPS recommendations Can anyone recommend a GPS that is in current production? I've been using the SKM52, which Hans Summers sells for use with his Ultimate 3. It works well, but I need a 2nd unit and though that I would consult the group before my purchase. 73 Phil N6WKZ ________________________________________ ______________________ GPS_Standard mailing list Home: http://mailman.qth.net/mailman/listinfo/ gps_standard Help: http://mailman.qth.net/mmfaq.htm Post: mailto:GPS_Standard at mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html From mark.fancher at twc.com Tue Oct 21 17:04:01 2014 From: mark.fancher at twc.com (Mark Fancher) Date: Tue, 21 Oct 2014 17:04:01 -0400 Subject: [GPS_Standard] GPS recommendations In-Reply-To: <5446b7a4.243d460a.5b54.2bb0@mx.google.com> References: <54468DBA.40406@comcast.net> <5446b7a4.243d460a.5b54.2bb0@mx.google.com> Message-ID: <002f01cfed72$8a9f8b00$9fdea100$@twc.com> Does the Adafruit model provide the necessary accuracy? -----Original Message----- From: GPS_Standard [mailto:gps_standard-bounces at mailman.qth.net] On Behalf Of Peter Mulhare Sent: Tuesday, October 21, 2014 3:45 PM To: gps_standard at mailman.qth.net Cc: 'Phil' Subject: Re: [GPS_Standard] GPS recommendations Hi Phil Personally I would try an Adafruit "Ultimate GPS Breakout - 66 channel w/10 Hz Updates using the MTK3339 chipset - v3". They operate at 5V or 3.3V, have an onboard Voltage regulator and its logic is 5V friendly. I use one in my VE2ZAZ board. Works well and is extremely small. It will require a 3.3V external antenna if you mount it in a box however. Adafruit sell a suitable external antenna and a small coax tail which converts the on board GPS antenna connector to SMA, to fit the external Antenna termination. The GPS units are currently around $US40.00 each and can be purchased from retailers or of eBay. Pete Mulhare ZL2iK -----Original Message----- From: GPS_Standard [mailto:gps_standard-bounces at mailman.qth .net] On Behalf Of Phil Sent: 22 October 2014 5:46 a.m. To: gps_standard at mailman.qth.net Subject: [GPS_Standard] GPS recommendations Can anyone recommend a GPS that is in current production? I've been using the SKM52, which Hans Summers sells for use with his Ultimate 3. It works well, but I need a 2nd unit and though that I would consult the group before my purchase. 73 Phil N6WKZ ________________________________________ ______________________ GPS_Standard mailing list Home: http://mailman.qth.net/mailman/listinfo/ gps_standard Help: http://mailman.qth.net/mmfaq.htm Post: mailto:GPS_Standard at mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ GPS_Standard mailing list Home: http://mailman.qth.net/mailman/listinfo/gps_standard Help: http://mailman.qth.net/mmfaq.htm Post: mailto:GPS_Standard at mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html