Re: [time-nuts] Rubidium as radio reference
Hi Simple - feed it in at the high side of the crystal. Still easy - pop out the crystal and feed it in there. More complex - re-wire the base of Q101 so it's detached from all the caps and crystals. It's now a comm emitter buffer. AC couple the signal in there. Of course you still have the problem that the output of the FE is *very* messy at RF. Bob On Oct 30, 2012, at 8:28 PM, Joseph Gray jg...@zianet.com wrote: I know that some here are Amateurs and have used external sources to provide a more accurate reference for a receiver. So, I have a noob question or two. Is the programmable FE-5680A suitable to replace the 12.8 MHz reference in a Midland XTR? If so, where do I feed the rubidium into the circuit (see attached screen clip)? X101 is the 12.8 MHz crystal and R107 is used for temperature compensation. What I have in mind is to use the XTR radio for measuring off-the-air carrier frequency error. It's just part of a project that I've been thinking of doing. Things are still in the planning and experimenting stage. Joe Gray W5JG ScreenClip.png___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rubidium as radio reference
I would question the ability to change it. Not familiar with the radio, but fcontrol feeds back to the 12.8Mhz oscillator by a varicap. If its part of the pll of the radio then no. If its a RIT control then as mentioned yes. The RIT will no longer work. Regards Paul WB8TSL On Sun, Nov 4, 2012 at 7:26 AM, Bob Camp li...@rtty.us wrote: Hi Simple - feed it in at the high side of the crystal. Still easy - pop out the crystal and feed it in there. More complex - re-wire the base of Q101 so it's detached from all the caps and crystals. It's now a comm emitter buffer. AC couple the signal in there. Of course you still have the problem that the output of the FE is *very* messy at RF. Bob On Oct 30, 2012, at 8:28 PM, Joseph Gray jg...@zianet.com wrote: I know that some here are Amateurs and have used external sources to provide a more accurate reference for a receiver. So, I have a noob question or two. Is the programmable FE-5680A suitable to replace the 12.8 MHz reference in a Midland XTR? If so, where do I feed the rubidium into the circuit (see attached screen clip)? X101 is the 12.8 MHz crystal and R107 is used for temperature compensation. What I have in mind is to use the XTR radio for measuring off-the-air carrier frequency error. It's just part of a project that I've been thinking of doing. Things are still in the planning and experimenting stage. Joe Gray W5JG ScreenClip.png___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rubidium as radio reference
Can anyone explain the five day delay in Mr. Gray's mail? -Original Message- From: John Ackermann N8UR Sent: Sunday, November 04, 2012 6:23 AM Joe, the question is whether the DDS spurs and noise on the FE-5680A are strong enough to interfere with your measurements. I suspect that in the HF/VHF range, you'd probably be OK, at UHF maybe dicey, at microwave probably not good (assuming you're multiplying the Rb up). I have phase noise measurements of the narrow DDS version of the FE-5680A along with some other low-cost Rbs at http://febo.com/pages/oscillators/rubes/ 73, John On Oct 30, 2012, at 8:28 PM, Joseph Gray jg...@zianet.com wrote: I know that some here are Amateurs and have used external sources to provide a more accurate reference for a receiver. So, I have a noob question or two. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rubidium as radio reference
Several of the large carriers have had all manner of issues due to the storm; not only network issues but mail servers as well. Peter On 11/4/2012 11:02 AM, Bill Hawkins wrote: Can anyone explain the five day delay in Mr. Gray's mail? -Original Message- From: John Ackermann N8UR Sent: Sunday, November 04, 2012 6:23 AM Joe, the question is whether the DDS spurs and noise on the FE-5680A are strong enough to interfere with your measurements. I suspect that in the HF/VHF range, you'd probably be OK, at UHF maybe dicey, at microwave probably not good (assuming you're multiplying the Rb up). I have phase noise measurements of the narrow DDS version of the FE-5680A along with some other low-cost Rbs at http://febo.com/pages/oscillators/rubes/ 73, John On Oct 30, 2012, at 8:28 PM, Joseph Gray jg...@zianet.com wrote: I know that some here are Amateurs and have used external sources to provide a more accurate reference for a receiver. So, I have a noob question or two. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5373 - Release Date: 11/04/12 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rubidium as radio reference
John, The radio is on 2M. Joe Gray W5JG On Sun, Nov 4, 2012 at 5:23 AM, John Ackermann N8UR j...@febo.com wrote: Joe, the question is whether the DDS spurs and noise on the FE-5680A are strong enough to interfere with your measurements. I suspect that in the HF/VHF range, you'd probably be OK, at UHF maybe dicey, at microwave probably not good (assuming you're multiplying the Rb up). I have phase noise measurements of the narrow DDS version of the FE-5680A along with some other low-cost Rbs at http://febo.com/pages/oscillators/rubes/ 73, John On Oct 30, 2012, at 8:28 PM, Joseph Gray jg...@zianet.com wrote: I know that some here are Amateurs and have used external sources to provide a more accurate reference for a receiver. So, I have a noob question or two. Is the programmable FE-5680A suitable to replace the 12.8 MHz reference in a Midland XTR? If so, where do I feed the rubidium into the circuit (see attached screen clip)? X101 is the 12.8 MHz crystal and R107 is used for temperature compensation. What I have in mind is to use the XTR radio for measuring off-the-air carrier frequency error. It's just part of a project that I've been thinking of doing. Things are still in the planning and experimenting stage. Joe Gray W5JG ScreenClip.png ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rubidium as radio reference
On Tue, Oct 30, 2012 at 5:28 PM, Joseph Gray jg...@zianet.com wrote: Is the programmable FE-5680A suitable to replace the 12.8 MHz reference in a Midland XTR? If so, where do I feed the rubidium into the circuit The long term characteristics of the Rb are very good. But short term a crystal oscillator might be better. You can have the best of both if you phase lock a crystal oscillator to the Rb. This whould give you something more like the GPSDO where the 10MHz output is from a crystal but there is a control on the longer term drift. You'd have a Rubiidium disciplined XO. You still need access to some kind of standard like from GPS so you can calibrate the Rb. Your best bet would be to build a GPSDO that runs directly at the desired 12.8Mhz. Most off the shelf GPSDOs run at 10Mhz so this is a good reason to DIY. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rubidium as radio reference
Hi Joe, The reference oscillator is only part of the story. Being a typical FM radio the normal method is to observe when the carrier is in the center of the discriminator's bandpass. The particular center point is not a constant, per se, because the discriminator is typically adjusted so that the swing of the modulation is symmetrical and that is not usually at the exact center. The discriminator itself may not be symmetrical and often times the center is skewed because of it. Therefore you cannot necessarily rely on the center point as being on frequency. In addition to the so-called reference frequency, you would also have to stabilize the oscillators that feed the mixers if there is more than one IF frequency involved, which is usually the case. The typical stability of these types of radios are pretty good but no where near time-nuts type stuff. When transmitting, the heat build up inside the radio will alter the transmit frequency by a few hertz to as much as few 100 hertz depending upon the particular radio. This is normal and usually does not affect the ability to communicate due to the wide bandwidth of both the IF's and the discriminator. At the receiving end you can watch such action in real time over the length of the transmission. If you are really trying to do something more in line with timenuts type stuff, you will, most likely, need to do a different approach. Perhaps you could give more details allowing for a better run of suggestions. As for the FE-5680 Rb, it would require some filtering and such. Instead of trying to modify the radio for a direct feed from the Rb it would serve you better as a source in a PLL type arrangement. Just my two cents. So give us more details. BillWB6BNQ Joseph Gray wrote: I know that some here are Amateurs and have used external sources to provide a more accurate reference for a receiver. So, I have a noob question or two. Is the programmable FE-5680A suitable to replace the 12.8 MHz reference in a Midland XTR? If so, where do I feed the rubidium into the circuit (see attached screen clip)? X101 is the 12.8 MHz crystal and R107 is used for temperature compensation. What I have in mind is to use the XTR radio for measuring off-the-air carrier frequency error. It's just part of a project that I've been thinking of doing. Things are still in the planning and experimenting stage. Joe Gray W5JG Name: ScreenClip.png ScreenClip.pngType: PNG Image (image/png) Encoding: base64 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rubidium as radio reference
Joseph Gray wrote: Internet is flaky lately. I'll be brief, as I'm sending this from my phone. I don't need timenut accuracy for this. I want to make a setup for measuring off the air, so local amateurs can have some way to check a radio. Using a service monitor, I can get a linear AC voltage from the discriminator that corresponds to deviation. I can also measure a DC noise squelch voltage that is inversely proportional to RSS, but not linear. For carrier error, I get about 3V DC at the discriminator for on frequency. Then I get a linear relationship for off frequency. I still need to figure out how to measure these voltages with an ADC and interface to a R-Pi. Just a fun project, I thought. Joe Gray W5JG On Nov 4, 2012 4:15 PM, WB6BNQ [1]wb6...@cox.net wrote: Hi Joe, The reference oscillator is only part of the story. Being a typical FM radio the normal method is to observe when the carrier is in the center of the discriminator's bandpass. The particular center point is not a constant, per se, because the discriminator is typically adjusted so that the swing of the modulation is symmetrical and that is not usually at the exact center. The discriminator itself may not be symmetrical and often times the center is skewed because of it. Therefore you cannot necessarily rely on the center point as being on frequency. In addition to the so-called reference frequency, you would also have to stabilize the oscillators that feed the mixers if there is more than one IF frequency involved, which is usually the case. The typical stability of these types of radios are pretty good but no where near time-nuts type stuff. When transmitting, the heat build up inside the radio will alter the transmit frequency by a few hertz to as much as few 100 hertz depending upon the particular radio. This is normal and usually does not affect the ability to communicate due to the wide bandwidth of both the IF's and the discriminator. At the receiving end you can watch such action in real time over the length of the transmission. If you are really trying to do something more in line with timenuts type stuff, you will, most likely, need to do a different approach. Perhaps you could give more details allowing for a better run of suggestions. As for the FE-5680 Rb, it would require some filtering and such. Instead of trying to modify the radio for a direct feed from the Rb it would serve you better as a source in a PLL type arrangement. Just my two cents. So give us more details. BillWB6BNQ Joseph Gray wrote: I know that some here are Amateurs and have used external sources to provide a more accurate reference for a receiver. So, I have a noob question or two. Is the programmable FE-5680A suitable to replace the 12.8 MHz reference in a Midland XTR? If so, where do I feed the rubidium into the circuit (see attached screen clip)? X101 is the 12.8 MHz crystal and R107 is used for temperature compensation. What I have in mind is to use the XTR radio for measuring off-the-air carrier frequency error. It's just part of a project that I've been thinking of doing. Things are still in the planning and experimenting stage. Joe Gray W5JG Name: ScreenClip.png ScreenClip.pngType: PNG Image (image/png) Encoding: base64 ___ time-nuts mailing list -- [2]time-nuts@febo.com To unsubscribe, go to [3]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. References 1. mailto:wb6...@cox.net 2. mailto:time-nuts@febo.com 3. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
