New 70 cm Receiver Test Results
Re: 70 cm Prototype Receiver Testing
John, and group,
I set up my shop this evening to take a look at the microphonic issue that I had noticed before Dayton. I decided to use my new SDR-IQ software defined radio instead of my HP 8566B spectrum analyzer. The SDR-IQ has a lower noise floor, is quiet, and doesn't heat up my shack. Of course it tops out at 30 MHz and the 8566B goes up to 22 GHz. But for this application all I needed was something to look at the IF output at 10.7 MHz.
Before I got to the microphonics I noticed spurs and phase noise that I had not previously seen with the 8566B - a classic case of going to drain the swamp and then ending up fighting alligators...
I've posted screen shots and test details on EaglePedia's 70 cm receiver page. Click here http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Testing_Resumed.htm for a link to that top level page.
Then go down to the Project Status area and open up Troubleshooting http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Testing_Resumed.htm Resumes. I wouldn't get discouraged. This is why we built the prototype in the first place - to find all the little flaws that need attention.
More to follow in a few days...
P.S. I add new material to the end of these logs so if you've already read the earlier posting just scroll down to the new material at the end. I always try to note the date and time I last modified the log at the top so you can see if there is anything new since your last visit.
73,
Juan
WA6HTP
Tom,
John had also asked me to adjust the power supply voltage slowly over its entire input range while watching for spurs. I couldn't see anything with my spectrum analyzer but the SDR-IQ's noise floor is much lower and it's very fast. I'll try that test this weekend. Those spurs might be switching noise from the supply.
One of the few pieces of test equipment I actually purchaed new was a low-cost tektronix oscilloscope. It's about 15 years old now and not functioning all that well. I'll give the SDR-IQ a try with a scope probe on the PLL loop and report back this weekend.
73,
Juan
On 6/7/07, Tom Clark, K3IO K3IO@verizon.net wrote:
Juan -- a couple of thoughts that came to my mind based on your blow-by-blow report:
- You might command a move off 435.000. As I recall, the
synthesizer reference is at 10.000 MHz. I could conceive an internal spur generated by the reference oscillator. 2. The 6.8 kHz spur interval is certainly weird, but it sounds like it might be due to the synthesizer chip's RC low-pass filter with a time constant ~ 1/6.8 kHz = ~140µs. Is it possible that something inside the loop is oscillating? Try a scope probe on the VCO's tuning voltage. 3. On topic #2, is it possible that you can see microphonic on the tuning voltage? 4. I'm interested to see that you also find the IQ as a very useful piece of test equipment. Here is another test you might want to try: Remember that the IQ does down to (nearly) DC. You could try using it to look at the spectrum of the synthesizer tuning voltage over the ~0-20 kHz range. If the chip is locked, there should be very little noise; but with the spectrum you are showing, I wouldn't be surprised to see noise that mimics the 10.7 MHz power spectra you show herehttp://www.juanr.com/pages/hobbies/ham_radio/Eagle/Testing_Resumed.htm
73, Tom
Since the noise is always symmetrical around the received signal, the switcher noise must be modulating the VCO control voltages. There are two switchers - one on the receiver PCB and one on the CAN-DO module. We must determine which is causing the problem or whether both are. Can you cut the trace on the PCB and vary the DC voltage to the receiver independently of the voltage to the CAN-Do module?
I hope that you can tap each component and find the microphionic one. Good candidates for microphonic components are the capacitors in the PLL feedback loop. The capacitors in the integrator are film types so they shouldn't be microphonic but perhaps SMT parts aren't as good as leaded parts. The ceramic capactors in the feedback path might also cause problems and could be changed to film capacitors. Another possibility may be the 4.7 and 10 uF bypass capacitors on the outputs of the linear regulators. These are ceramic because of concerns about tantalums in space but they might have good piezoelectric properties and could be switched to 1206 size tantalum capacitors. There could also be a cold solder joint somewhere.
73,
John KD6OZH ----- Original Message ----- From: Juan Rivera To: John B. Stephensen ; eagle@amsat.org Cc: Bill Ress ; Dave Black (Home) ; Dave Black (Work) ; Dave hartzell ; David Smith ; Don Ferguson ; Juan. Rivera (Home) ; Juan.Rivera (Work) ; Samsonoff@Mac. Com Sent: Friday, June 08, 2007 03:45 UTC Subject: New 70 cm Receiver Test Results
Re: 70 cm Prototype Receiver Testing
John, and group,
I set up my shop this evening to take a look at the microphonic issue that I had noticed before Dayton. I decided to use my new SDR-IQ software defined radio instead of my HP 8566B spectrum analyzer. The SDR-IQ has a lower noise floor, is quiet, and doesn't heat up my shack. Of course it tops out at 30 MHz and the 8566B goes up to 22 GHz. But for this application all I needed was something to look at the IF output at 10.7 MHz.
Before I got to the microphonics I noticed spurs and phase noise that I had not previously seen with the 8566B - a classic case of going to drain the swamp and then ending up fighting alligators...
I've posted screen shots and test details on EaglePedia's 70 cm receiver page. Click here for a link to that top level page.
Then go down to the Project Status area and open up Troubleshooting Resumes. I wouldn't get discouraged. This is why we built the prototype in the first place - to find all the little flaws that need attention.
More to follow in a few days...
P.S. I add new material to the end of these logs so if you've already read the earlier posting just scroll down to the new material at the end. I always try to note the date and time I last modified the log at the top so you can see if there is anything new since your last visit.
73,
Juan
WA6HTP
John B. Stephensen wrote:
Since the noise is always symmetrical around the received signal, the switcher noise must be modulating the VCO control voltages. There are two switchers - one on the receiver PCB and one on the CAN-DO module. We must determine which is causing the problem or whether both are. Can you cut the trace on the PCB and vary the DC voltage to the receiver independently of the voltage to the CAN-Do module?
I agree with this switcher comment and did as soon as I saw the picture. I really hope this is not the CAN-DO module as FLIGHT UNITS have been DELIVERED for P3E. We need to have Stephen, et. al. check the noise output of the switcher on the Can-Do module.
I hope that you can tap each component and find the microphionic one. Good candidates for microphonic components are the capacitors in the PLL feedback loop. The capacitors in the integrator are film types so they shouldn't be microphonic but perhaps SMT parts aren't as good as leaded parts. The ceramic capactors in the feedback path might also cause problems and could be changed to film capacitors. Another possibility may be the 4.7 and 10 uF bypass capacitors on the outputs of the linear regulators. These are ceramic because of concerns about tantalums in space but they might have good piezoelectric properties and could be switched to 1206 size tantalum capacitors. There could also be a cold solder joint somewhere.
73,
John KD6OZH
Switching Noise: My preliminary "sniff" last night didn't detect any noise near the Can-do module. The overwhelming amount of noise was picked up when the probe was near L21. I could also vary the frequency by adjusting the DC input voltage to the radio, putting both the "sniffed" and the IF output spikes on 5.0 kHz with the same input voltage. I'll look deeper later today but I believe the IF spurs are coming from the receiver switcher and not the Can-do module.
The spec sheet for the max1776 goes to lengths to warn about how critical the layout is due to high peak switching currents. It also discusses radiated noise. See the section on PC board layout and grounding. If the supply and the RF section share the same common ground to the Can-do module I can easily see how switching noise could couple into the radio.
Since we have unused space at the back of the board I'd suggest isolating the supply away from the RF section and separating the power and RF grounds. The DC from the Can-do module could be brought back to the power supply via a short section of coax or a twisted pair to keep the DC noise isolated from the receiver ground completely.
Microphonics: I spent quite a while trying to isolate the microphonic source. I softly dragged an insulated probe across every component on the board. Some areas of the board seem to produce more noise than others but no single component jumps out. John, if you're right and its several ceramic capacitors that should be film that might explain it. I'll try to zero in on this later today.
73,
Juan WA6HTP
-----Original Message----- From: Robert McGwier [mailto:rwmcgwier@gmail.com] Sent: Saturday, June 09, 2007 7:04 AM To: John B. Stephensen Cc: juan-rivera@sbcglobal.net; eagle@amsat.org; David Smith; Dave Black (Work); Dave Black (Home); Samsonoff@Mac. Com; Juan.Rivera (Work) Subject: Re: [eagle] Re: New 70 cm Receiver Test Results
John B. Stephensen wrote:
Since the noise is always symmetrical around the received signal, the switcher noise must be modulating the VCO control voltages. There are two switchers - one on the receiver PCB and one on the CAN-DO module. We must determine which is causing the problem or whether both are. Can you cut the trace on the PCB and vary the DC voltage to the receiver independently of the voltage to the CAN-Do module?
I agree with this switcher comment and did as soon as I saw the picture. I really hope this is not the CAN-DO module as FLIGHT UNITS have been DELIVERED for P3E. We need to have Stephen, et. al. check the noise output of the switcher on the Can-Do module.
I hope that you can tap each component and find the microphionic one. Good candidates for microphonic components are the capacitors in the PLL feedback loop. The capacitors in the integrator are film types so they shouldn't be microphonic but perhaps SMT parts aren't as good as leaded parts. The ceramic capactors in the feedback path might also cause problems and could be changed to film capacitors. Another possibility may be the 4.7 and 10 uF bypass capacitors on the outputs of the linear regulators. These are ceramic because of concerns about tantalums in space but they might have good piezoelectric properties and could be switched to 1206 size tantalum capacitors. There could also be a cold solder joint somewhere.
73,
John KD6OZH
Juan:
This also points to the folly of making a circuit so small and yet leaving available PCB area unused. :-) (I still like my thru-board components and construction!)
Dick Jansson, KD1K kd1k@amsat.org kd1k@arrl.net ---------------------------
-----Original Message----- From: eagle-bounces@amsat.org [mailto:eagle-bounces@amsat.org] On Behalf Of Juan Rivera Sent: Saturday, 09 June, 2007 1439 To: 'Robert McGwier'; 'John B. Stephensen' Cc: 'David Smith'; 'Dave Black (Work)'; 'Dave Black (Home)'; eagle@amsat.org; 'Samsonoff@Mac. Com'; 'Juan.Rivera (Work)' Subject: [eagle] Re: New 70 cm Receiver Test Results
Switching Noise: My preliminary "sniff" last night didn't detect any noise near the Can-do module. The overwhelming amount of noise was picked up when the probe was near L21. I could also vary the frequency by adjusting the DC input voltage to the radio, putting both the "sniffed" and the IF output spikes on 5.0 kHz with the same input voltage. I'll look deeper later today but I believe the IF spurs are coming from the receiver switcher and not the Can-do module.
The spec sheet for the max1776 goes to lengths to warn about how critical the layout is due to high peak switching currents. It also discusses radiated noise. See the section on PC board layout and grounding. If the supply and the RF section share the same common ground to the Can-do module I can easily see how switching noise could couple into the radio.
Since we have unused space at the back of the board I'd suggest isolating the supply away from the RF section and separating the power and RF grounds. The DC from the Can-do module could be brought back to the power supply via a short section of coax or a twisted pair to keep the DC noise isolated from the receiver ground completely.
Microphonics: I spent quite a while trying to isolate the microphonic source. I softly dragged an insulated probe across every component on the board. Some areas of the board seem to produce more noise than others but no single component jumps out. John, if you're right and its several ceramic capacitors that should be film that might explain it. I'll try to zero in on this later today.
73,
Juan WA6HTP
-----Original Message----- From: Robert McGwier [mailto:rwmcgwier@gmail.com] Sent: Saturday, June 09, 2007 7:04 AM To: John B. Stephensen Cc: juan-rivera@sbcglobal.net; eagle@amsat.org; David Smith; Dave Black (Work); Dave Black (Home); Samsonoff@Mac. Com; Juan.Rivera (Work) Subject: Re: [eagle] Re: New 70 cm Receiver Test Results
John B. Stephensen wrote:
Since the noise is always symmetrical around the received signal, the switcher noise must be modulating the VCO control voltages. There are two switchers - one on the receiver PCB and one on the CAN-DO module. We must determine which is causing the problem or whether both are. Can you cut the trace on the PCB and vary the DC voltage to the receiver independently of the voltage to the CAN-Do module?
I agree with this switcher comment and did as soon as I saw the picture. I really hope this is not the CAN-DO module as FLIGHT UNITS have been DELIVERED for P3E. We need to have Stephen, et. al. check the noise output of the switcher on the Can-Do module.
I hope that you can tap each component and find the microphionic one. Good candidates for microphonic components are the capacitors in the PLL feedback loop. The capacitors in the integrator are film types so they shouldn't be microphonic but perhaps SMT parts aren't as good as leaded parts. The ceramic capactors in the feedback path might also cause problems and could be changed to film capacitors. Another possibility may be the 4.7 and 10 uF bypass capacitors on the outputs of the linear regulators. These are ceramic because of concerns about tantalums in space but they might have good piezoelectric properties and could be switched to 1206 size tantalum capacitors. There could also be a cold solder joint somewhere.
73,
John KD6OZH
Folks,
I've bypassed U17, the 10 volt step-down converter, in an effort to isolate the cause of the spurs in the IF output. I've also started a new log. You can jump there by clicking http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Troubleshooting_Spurs.ht m here, or go to the AMSAT 70 cm receiver page and click on Spur Troubleshooting under Project Status.
73,
Juan
WA6HTP
Juan:: Did you also DISABLE the switcher? If not, it may still be making noise, either radiated, or coupled through grounds as someone else has suggested.
Thanks for all the work on this. 73, Jim
John: Juan's reference to the data sheet generates a wild thought: At your convenience, could you produce a document consisting of links to the data sheets on the active components? We could then add that to the receiver page on EaglePedia and have ONE entry point to all information on this receiver. Obviously not urgent. . . .
Thanks & 73, Jim
Juan Rivera wrote:
Folks,
I've bypassed U17, the 10 volt step-down converter, in an effort to isolate the cause of the spurs in the IF output. I've also started a new log. You can jump there by clicking here http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Troubleshooting_Spurs.htm, or go to the AMSAT 70 cm receiver page and click on _Spur Troubleshooting_ under _Project Status_.
73,
Juan
WA6HTP
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
Jim,
Yes, I removed the input and output filters from that stage and I'm feeding its load with an external power supply.
Juan
_____
From: Jim Sanford [mailto:wb4gcs@amsat.org] Sent: Saturday, June 09, 2007 3:04 PM To: juan-rivera@sbcglobal.net Cc: 'Robert McGwier'; 'John B. Stephensen'; 'David Smith'; 'Dave Black (Work)'; 'Dave Black (Home)'; eagle@amsat.org; 'Samsonoff@Mac. Com'; 'Juan.Rivera (Work)' Subject: Re: [eagle] Re: New 70 cm Receiver Test Results
Juan:: Did you also DISABLE the switcher? If not, it may still be making noise, either radiated, or coupled through grounds as someone else has suggested.
Thanks for all the work on this. 73, Jim
John: Juan's reference to the data sheet generates a wild thought: At your convenience, could you produce a document consisting of links to the data sheets on the active components? We could then add that to the receiver page on EaglePedia and have ONE entry point to all information on this receiver. Obviously not urgent. . . .
Thanks & 73, Jim
Juan Rivera wrote:
Folks,
I've bypassed U17, the 10 volt step-down converter, in an effort to isolate the cause of the spurs in the IF output. I've also started a new log. You can jump there by clicking http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Troubleshooting_Spurs.ht m here, or go to the AMSAT 70 cm receiver page and click on Spur Troubleshooting under Project Status.
73,
Juan
WA6HTP
_____
_______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
The 68 kHz spacing indicates that the source isn't the PLL as it's phase detector operates at 125 kHz. The switching regulator on the CAN-Do module should be the only device that changes frequency with input voltage.
73,
John KD6OZH ----- Original Message ----- From: Juan Rivera To: 'Robert McGwier' ; 'John B. Stephensen' Cc: eagle@amsat.org ; 'David Smith' ; 'Dave Black (Work)' ; 'Dave Black (Home)' ; 'Samsonoff@Mac. Com' ; 'Juan.Rivera (Work)' Sent: Saturday, June 09, 2007 20:25 UTC Subject: RE: [eagle] Re: New 70 cm Receiver Test Results
Folks,
I've bypassed U17, the 10 volt step-down converter, in an effort to isolate the cause of the spurs in the IF output. I've also started a new log. You can jump there by clicking here, or go to the AMSAT 70 cm receiver page and click on Spur Troubleshooting under Project Status.
73,
Juan
WA6HTP
John,
I've made more progress. Rather than repeat it here please see the log.
73,
Juan
WA6HTP
_____
From: John B. Stephensen [mailto:kd6ozh@comcast.net] Sent: Saturday, June 09, 2007 6:15 PM To: juan-rivera@sbcglobal.net; 'Robert McGwier' Cc: eagle@amsat.org; 'David Smith'; 'Dave Black (Work)'; 'Dave Black (Home)'; 'Samsonoff@Mac. Com'; 'Juan.Rivera (Work)' Subject: Re: [eagle] Re: New 70 cm Receiver Test Results
The 68 kHz spacing indicates that the source isn't the PLL as it's phase detector operates at 125 kHz. The switching regulator on the CAN-Do module should be the only device that changes frequency with input voltage.
73,
John
KD6OZH
----- Original Message -----
From: Juan mailto:juan-rivera@sbcglobal.net Rivera
To: 'Robert McGwier' mailto:rwmcgwier@gmail.com ; 'John B. mailto:kd6ozh@comcast.net Stephensen'
Cc: eagle@amsat.org ; 'David Smith' mailto:w6te@msn.com ; 'Dave mailto:dblack@mail.arc.nasa.gov Black (Work)' ; 'Dave Black (Home)' mailto:dblack1054@yahoo.com ; 'Samsonoff@Mac. mailto:'Samsonoff@Mac.%20Com' Com' ; 'Juan.Rivera (Work)' mailto:Juan.Rivera@gd-ais.com
Sent: Saturday, June 09, 2007 20:25 UTC
Subject: RE: [eagle] Re: New 70 cm Receiver Test Results
Folks,
I've bypassed U17, the 10 volt step-down converter, in an effort to isolate the cause of the spurs in the IF output. I've also started a new log. You can jump there by clicking http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Troubleshooting_Spurs.ht m here, or go to the AMSAT 70 cm receiver page and click on Spur Troubleshooting under Project Status.
73,
Juan
WA6HTP
Folks,
I am quitting for the evening. I just posted more data on my web (at 1945 Pacific time). You can jump there by clicking http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Troubleshooting_Spurs.ht m here, or go to the AMSAT 70 cm receiver page and click on Spur Troubleshooting under Project Status.
I was able to remove power from the Can-do module and power the receiver from external power supplies. All of the spurs disappeared when the 13 volts was removed from the module. Tomorrow I'll start reconnecting the receiver internal power supply sections and see how far I can get before spurs reappear. I do not believe all the noise is coming from the Can-do module. Tomorrow I'll find out for sure.
73,
Juan
WA6HTP
Reconnect the switcher on the receiver PCB and see what shows up.
To eliminate the noise, we may have to connect the PCB to the CAN-Do widget with a ribbon cable and place it at the other end of the module case. If the internal switcher also pollutes the VCO control voltage, it could be moved to a separate PCB.
73,
John KD6OZH ----- Original Message ----- From: Juan Rivera To: juan-rivera@sbcglobal.net ; 'John B. Stephensen' ; 'Robert McGwier' Cc: eagle@amsat.org ; 'David Smith' ; 'Dave Black (Work)' ; 'Dave Black (Home)' ; 'Samsonoff@Mac. Com' ; 'Juan.Rivera (Work)' Sent: Sunday, June 10, 2007 02:47 UTC Subject: RE: [eagle] Re: New 70 cm Receiver Test Results
Folks,
I am quitting for the evening. I just posted more data on my web (at 1945 Pacific time). You can jump there by clicking here, or go to the AMSAT 70 cm receiver page and click on Spur Troubleshooting under Project Status.
I was able to remove power from the Can-do module and power the receiver from external power supplies. All of the spurs disappeared when the 13 volts was removed from the module. Tomorrow I'll start reconnecting the receiver internal power supply sections and see how far I can get before spurs reappear. I do not believe all the noise is coming from the Can-do module. Tomorrow I'll find out for sure.
73,
Juan
WA6HTP
John,
I'll tackle that tomorrow. For this prototype we can actually do exactly what you suggest and just move the PCB back one set of standoffs and leave the Can-Do module where it is. Of course the SMA connectors will be inaccessible with the cover on but I don't run it that way when testing anyway, so it won't matter.
Getting the Can-do module desoldered won't be much fun but it should be possible. That's a job for next week. I think I'll find tomorrow that U17 is also a contributor to the noise. Perhaps I should cut into the VCO control loop and control the VCO with an external supply if it starts to look like a culprit. Right now I'm out of variable supplies since all three are tied up. I don't have an oscilloscope that I trust but I may be able to use the SDR-IQ with a scope probe to look at the VCO control loop since it goes down to 500 Hz. That will be an interesting test. This little radio is very useful.
73,
Juan
_____
From: John B. Stephensen [mailto:kd6ozh@comcast.net] Sent: Saturday, June 09, 2007 8:08 PM To: juan-rivera@sbcglobal.net; 'Robert McGwier' Cc: eagle@amsat.org; 'David Smith'; 'Dave Black (Work)'; 'Dave Black (Home)'; 'Samsonoff@Mac. Com'; 'Juan.Rivera (Work)' Subject: Re: [eagle] Re: New 70 cm Receiver Test Results
Reconnect the switcher on the receiver PCB and see what shows up.
To eliminate the noise, we may have to connect the PCB to the CAN-Do widget with a ribbon cable and place it at the other end of the module case. If the internal switcher also pollutes the VCO control voltage, it could be moved to a separate PCB.
73,
John
KD6OZH
----- Original Message -----
From: Juan mailto:juan-rivera@sbcglobal.net Rivera
To: juan-rivera@sbcglobal.net ; 'John B. mailto:kd6ozh@comcast.net Stephensen' ; 'Robert McGwier' mailto:rwmcgwier@gmail.com
Cc: eagle@amsat.org ; 'David Smith' mailto:w6te@msn.com ; 'Dave mailto:dblack@mail.arc.nasa.gov Black (Work)' ; 'Dave Black (Home)' mailto:dblack1054@yahoo.com ; 'Samsonoff@Mac. mailto:'Samsonoff@Mac.%20Com' Com' ; 'Juan.Rivera (Work)' mailto:Juan.Rivera@gd-ais.com
Sent: Sunday, June 10, 2007 02:47 UTC
Subject: RE: [eagle] Re: New 70 cm Receiver Test Results
Folks,
I am quitting for the evening. I just posted more data on my web (at 1945 Pacific time). You can jump there by clicking http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Troubleshooting_Spurs.ht m here, or go to the AMSAT 70 cm receiver page and click on Spur Troubleshooting under Project Status.
I was able to remove power from the Can-do module and power the receiver from external power supplies. All of the spurs disappeared when the 13 volts was removed from the module. Tomorrow I'll start reconnecting the receiver internal power supply sections and see how far I can get before spurs reappear. I do not believe all the noise is coming from the Can-do module. Tomorrow I'll find out for sure.
73,
Juan
WA6HTP
Juan
The VCO control line will be extreemly sensitive to noise; testing VCOs with a power supply often gives more data about the power supply noise than the VCO performance. If you want to open the loop and control the VCO directly, I would suggest controlling the VCO using a battery with a potentiometer (10 turn if possible, or 'padded down' with resistors to give a reduced VCO control range) and maybe a large value parallel capacitor or two.
regards
Grant G8UBN
Juan Rivera wrote:
John,
I’ll tackle that tomorrow. For this prototype we can actually do exactly what you suggest and just move the PCB back one set of standoffs and leave the Can-Do module where it is. Of course the SMA connectors will be inaccessible with the cover on but I don’t run it that way when testing anyway, so it won’t matter.
Getting the Can-do module desoldered won’t be much fun but it should be possible. That’s a job for next week. I think I’ll find tomorrow that U17 is also a contributor to the noise. Perhaps I should cut into the VCO control loop and control the VCO with an external supply if it starts to look like a culprit. Right now I’m out of variable supplies since all three are tied up. I don’t have an oscilloscope that I trust but I may be able to use the SDR-IQ with a scope probe to look at the VCO control loop since it goes down to 500 Hz. That will be an interesting test. This little radio is very useful.
73,
Juan
Grant,
Thank you. That's a good idea and saves one power supply. I'll go with the battery and ten-turn pot method.
73,
Juan
-----Original Message----- From: eagle-bounces@amsat.org [mailto:eagle-bounces@amsat.org] On Behalf Of Grant Hodgson Sent: Sunday, June 10, 2007 12:42 AM Cc: 'Dave Black (Home)'; 'David Smith'; eagle@amsat.org; 'Dave Black (Work)' Subject: [eagle] Re: New 70 cm Receiver Test Results
Juan
The VCO control line will be extreemly sensitive to noise; testing VCOs with a power supply often gives more data about the power supply noise than the VCO performance. If you want to open the loop and control the VCO directly, I would suggest controlling the VCO using a battery with a potentiometer (10 turn if possible, or 'padded down' with resistors to give a reduced VCO control range) and maybe a large value parallel capacitor or two.
regards
Grant G8UBN
Juan Rivera wrote:
John,
I'll tackle that tomorrow. For this prototype we can actually do exactly what you suggest and just move the PCB back one set of standoffs and leave the Can-Do module where it is. Of course the SMA connectors will be inaccessible with the cover on but I don't run it that way when testing anyway, so it won't matter.
Getting the Can-do module desoldered won't be much fun but it should be possible. That's a job for next week. I think I'll find tomorrow that U17 is also a contributor to the noise. Perhaps I should cut into the VCO control loop and control the VCO with an external supply if it starts to look like a culprit. Right now I'm out of variable supplies since all three are tied up. I don't have an oscilloscope that I trust but I may be able to use the SDR-IQ with a scope probe to look at the VCO control loop since it goes down to 500 Hz. That will be an interesting test. This little radio is very useful.
73,
Juan
_______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
All,
As I troubleshoot the 70 cm receiver I stop and add to my logs every few minutes. I won't bother to announce every step I take (I just made an addition) because it takes too long. If you are interested please check the latest log at the top of the list or go to my web site. If you have a comment or suggestion just drop me an email via this Eagle/AMSAT mailer and everyone can participate. I'll check email often when I'm working on this project.
Here's the link to the AMSAT/Eagle receiver page --> http://www.amsat.org/amsat-new/eagle/EaglePedia/index.php/U-Band_Receiver
From there find the latest log at the top of the list under Project Status.
At the moment it's 'Spur Troubleshooting'
Or...
Go to my web at http://www.juanr.com/
Select Amateur Radio, select AMSAT/Eagle, and select the log you want to see from the menu.
73,
Juan
WA6HTP
The time that I spent optimizing the layout of the U17 switching regulator appears to be worth it if it isn't polluting the VCOs. What would be ideal is a module case where the CAN bus can exit from one side and the RF and IF from the other.
For now, the RF and IF can be run back to the connector bracket with SMA jumper cables. What is needed is a CAN-Do widget without the header connector so that wire leads can carry power and signals to the receiver PCB. 18-22 guage wire should work for power and 22-26 guage for signals. The wires need to be wound around a torroidal ferrite core to kill any common-mode noise. It may also be necessary to run the coax through ferrite beads. Do you have any beads or torroids made of material 75 or 77?
73,
John KD6OZH ----- Original Message ----- From: Juan Rivera To: eagle@amsat.org Sent: Sunday, June 10, 2007 17:59 UTC Subject: [eagle] Latest 70 cm Receiver Test Results
All,
As I troubleshoot the 70 cm receiver I stop and add to my logs every few minutes. I won't bother to announce every step I take (I just made an addition) because it takes too long. If you are interested please check the latest log at the top of the list or go to my web site. If you have a comment or suggestion just drop me an email via this Eagle/AMSAT mailer and everyone can participate. I'll check email often when I'm working on this project.
Here's the link to the AMSAT/Eagle receiver page --> http://www.amsat.org/amsat-new/eagle/EaglePedia/index.php/U-Band_Receiver
From there find the latest log at the top of the list under Project Status. At the moment it's 'Spur Troubleshooting'
Or...
Go to my web at http://www.juanr.com/
Select Amateur Radio, select AMSAT/Eagle, and select the log you want to see from the menu.
73,
Juan
WA6HTP
------------------------------------------------------------------------------
_______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
John and group,
Questions:
1) What about the phase noise? I'm assuming that that big hump is phase noise. Do you consider that to be excessive?
2) What about the passband ripple? That needs to get fixed.
3) If the next generation of the radio is going to be autonomous, fixed tuned, and have continuous power, what exactly is the CAN-Do module doing except returning a few parameters to the IHU? It makes sense to me to get it away from the radio completely. You can feed it whatever it needs such as loop lock status and temperature. That also fixes our lack of front panel space problem.
Until question 3 is resolved it doesn't make any sense to me to spend the time necessary to desolder the CAN-Do module and relocate it. For now we can initialize the receiver and then kill the CAN-DO module (RFC10 id removed and the receiver is powered separately.) That will create the same conditions as perfect CAN-Do module isolation would without the work.
I'd like to get back to the ATP testing but until we have items 1 and 2 resolved and correct the microphonics, there isn't too much sense in starting the ATP now. I'll focus on the microphonics while you folks digest this latest information.
By the say, are there new specs for the receiver yet? Is it still expected to cold soak to -70C? That's close to the temperature of liquid CO2 and well below the storage temperature of most components and way below the operating temperature limits.
73,
Juan
WA6HTP
_____
From: John B. Stephensen [mailto:kd6ozh@comcast.net] Sent: Sunday, June 10, 2007 12:51 PM To: juan-rivera@sbcglobal.net Cc: 'AMSAT Eagle' Subject: Re: [eagle] Latest 70 cm Receiver Test Results
The time that I spent optimizing the layout of the U17 switching regulator appears to be worth it if it isn't polluting the VCOs. What would be ideal is a module case where the CAN bus can exit from one side and the RF and IF from the other.
For now, the RF and IF can be run back to the connector bracket with SMA jumper cables. What is needed is a CAN-Do widget without the header connector so that wire leads can carry power and signals to the receiver PCB. 18-22 guage wire should work for power and 22-26 guage for signals. The wires need to be wound around a torroidal ferrite core to kill any common-mode noise. It may also be necessary to run the coax through ferrite beads. Do you have any beads or torroids made of material 75 or 77?
73,
John
KD6OZH
----- Original Message -----
From: Juan mailto:juan-rivera@sbcglobal.net Rivera
To: eagle@amsat.org
Sent: Sunday, June 10, 2007 17:59 UTC
Subject: [eagle] Latest 70 cm Receiver Test Results
All,
As I troubleshoot the 70 cm receiver I stop and add to my logs every few minutes. I won't bother to announce every step I take (I just made an addition) because it takes too long. If you are interested please check the latest log at the top of the list or go to my web site. If you have a comment or suggestion just drop me an email via this Eagle/AMSAT mailer and everyone can participate. I'll check email often when I'm working on this project.
Here's the link to the AMSAT/Eagle receiver page --> http://www.amsat.org/amsat-new/eagle/EaglePedia/index.php/U-Band_Receiver
From there find the latest log at the top of the list under Project Status.
At the moment it's 'Spur Troubleshooting'
Or...
Go to my web at http://www.juanr.com/
Select Amateur Radio, select AMSAT/Eagle, and select the log you want to see from the menu.
73,
Juan
WA6HTP
_____
_______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
By the say, are there new specs for the receiver yet? Is it still expected to cold soak to -70C? That’s close to the temperature of liquid CO2 and well below the storage temperature of most components and way below the operating temperature limits.
------------------------------ Juan:
There has never been any plan, specification, or thought of soaking any Eagle equipment to -70°C. The -70 number comes out of a very dynamic cooling situation that is barely possible and probably will not be allowed. This number comes from the fact that the higher power modules that are not conductively coupled to the spaceframe, such as are transmitters, could numerically get to the lower temperature range if it is unpowered or reduced power dissipation.
In a protracted eclipse (~2 hour), the outer shell of the spaceframe will get very cold, taking such modules as the URx down in temperature. This is a highly dynamic situation that has not yet been modeled, and it won't be until we have a spaceframe design on which to base such a model. Medium power modules such as the URx will have to have its outer cover emittance in the range of e = 0.45 or so because it will be mounted on the thermally isolated module mounting channels. Very low power modules, P < 1.0W, will be able to have the very low emittance of the AlClad aluminum and their lower temperatures will not be below ~-20°C. It is through these means that the critical command modules will not loose their functionality during eclipse, as I have noted previously. These numbers are not only analytical but have been confirmed by in-flight telemetry.
The BOE numbers go as follows: If the spaceframe cools to -100°C If the URx is powered to 3.5W, e = 0.45 If the URx is in thermal equilibrium Then the equilibrium temperature would be about -48.8°C
Under these same conditions, but with an E05 20 module that is P = 1.0W and e = 0.04, the equilibrium temperature would not be below 0°C. (Getting and keeping a module emittance that low is not very probable as there are wire lead conduction terms that affect the end result.)
There are too many "if" statements here before on which to base a specification at this point in time, but these are the issues that I have to deal with in trying to keep a spaceframe alive during eclipse. Module designers, on the other hand, must also be prepared for these kind of conditions and not expect a rosy comfortable arm chair environment during eclipses. Eclipses will be a fact of life, as they always have been, and I cannot make things better for you if the module power dissipation needs to bring the module emittance off of the bottom stop.
'73, Dick Jansson, KD1K mailto:kd1k@amsat.org kd1k@amsat.org mailto:kd1k@arrl.net kd1k@arrl.net ---------------------------
Dick: Simplisticly: What have we seen and designed to in the past? It would seem like that would be a reasonable requirement for both the payload teams and the thermal team. Give the payload guys a reasonable number to start with.
Thanks & 73, Jim wb4gcs@amsat.org
Dick Jansson-rr wrote:
By the say, are there new specs for the receiver yet? Is it still expected to cold soak to -70C? That’s close to the temperature of liquid CO2 and well below the storage temperature of most components and way below the operating temperature limits.
Juan:
There has never been any plan, specification, or thought of soaking any Eagle equipment to -70°C. The -70 number comes out of a very dynamic cooling situation that is barely possible and probably will not be allowed. This number comes from the fact that the higher power modules that are not conductively coupled to the spaceframe, such as are transmitters, could numerically get to the lower temperature range if it is unpowered or reduced power dissipation.
In a protracted eclipse (~2 hour), the outer shell of the spaceframe will get very cold, taking such modules as the URx down in temperature. This is a highly dynamic situation that has not yet been modeled, and it won't be until we have a spaceframe design on which to base such a model. Medium power modules such as the URx will have to have its outer cover emittance in the range of ? = 0.45 or so because it will be mounted on the thermally isolated module mounting channels. Very low power modules, P < 1.0W, will be able to have the very low emittance of the AlClad aluminum and their lower temperatures will not be below ~-20°C. It is through these means that the critical command modules will not loose their functionality during eclipse, as I have noted previously. These numbers are not only analytical but have been confirmed by in-flight telemetry.
The BOE numbers go as follows: If the spaceframe cools to -100°C If the URx is powered to 3.5W, ? = 0.45 If the URx is in thermal equilibrium Then the equilibrium temperature would be about -48.8°C
Under these same conditions, but with an E05 20 module that is P = 1.0W and ? = 0.04, the equilibrium temperature would not be below 0°C. (Getting and keeping a module emittance that low is not very probable as there are wire lead conduction terms that affect the end result.)
There are too many "if" statements here before on which to base a specification at this point in time, but these are the issues that I have to deal with in trying to keep a spaceframe alive during eclipse. Module designers, on the other hand, must also be prepared for these kind of conditions and not expect a rosy comfortable arm chair environment during eclipses. Eclipses will be a fact of life, as they always have been, and I cannot make things better for you if the module power dissipation needs to bring the module emittance off of the bottom stop.
'73, */Dick Jansson,/ KD1K* kd1k@amsat.org mailto:kd1k@amsat.org kd1k@arrl.net mailto:kd1k@arrl.net
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
MessageNot yet. -48.8 C is too cold so my current thought is to put the high power and low power components in separate modules so that the SAW filters are surrounded by relatively low power devices and that module can be insulated. I'm doing a redesign so that I can put realistic power dissipation figures in the new requirements document.
73,
John KD6OZH ----- Original Message ----- From: Dick Jansson-rr To: juan-rivera@sbcglobal.net ; 'John B. Stephensen' Cc: 'AMSAT Eagle' Sent: Sunday, June 10, 2007 23:57 UTC Subject: RE: [eagle] Re: Latest 70 cm Receiver Test Results
By the say, are there new specs for the receiver yet? Is it still expected to cold soak to -70C? That’s close to the temperature of liquid CO2 and well below the storage temperature of most components and way below the operating temperature limits.
------------------------------ Juan:
There has never been any plan, specification, or thought of soaking any Eagle equipment to -70°C. The -70 number comes out of a very dynamic cooling situation that is barely possible and probably will not be allowed. This number comes from the fact that the higher power modules that are not conductively coupled to the spaceframe, such as are transmitters, could numerically get to the lower temperature range if it is unpowered or reduced power dissipation.
In a protracted eclipse (~2 hour), the outer shell of the spaceframe will get very cold, taking such modules as the URx down in temperature. This is a highly dynamic situation that has not yet been modeled, and it won't be until we have a spaceframe design on which to base such a model. Medium power modules such as the URx will have to have its outer cover emittance in the range of e = 0.45 or so because it will be mounted on the thermally isolated module mounting channels. Very low power modules, P < 1.0W, will be able to have the very low emittance of the AlClad aluminum and their lower temperatures will not be below ~-20°C. It is through these means that the critical command modules will not loose their functionality during eclipse, as I have noted previously. These numbers are not only analytical but have been confirmed by in-flight telemetry.
The BOE numbers go as follows: If the spaceframe cools to -100°C If the URx is powered to 3.5W, e = 0.45 If the URx is in thermal equilibrium Then the equilibrium temperature would be about -48.8°C
Under these same conditions, but with an E05 20 module that is P = 1.0W and e = 0.04, the equilibrium temperature would not be below 0°C. (Getting and keeping a module emittance that low is not very probable as there are wire lead conduction terms that affect the end result.)
There are too many "if" statements here before on which to base a specification at this point in time, but these are the issues that I have to deal with in trying to keep a spaceframe alive during eclipse. Module designers, on the other hand, must also be prepared for these kind of conditions and not expect a rosy comfortable arm chair environment during eclipses. Eclipses will be a fact of life, as they always have been, and I cannot make things better for you if the module power dissipation needs to bring the module emittance off of the bottom stop.
'73, Dick Jansson, KD1K kd1k@amsat.org kd1k@arrl.net ---------------------------
The bump is the combined phase noise of the two VCOs. The maximums at either side show the approximate loop bandwidth. The measured phase noise is a few dB lower than the original requirements.
I think that we can ignore the ripple problem for now as the adjacent circuitry has to change to meet thermal requirements.
The microphonics problem needs to be resolved.
73,
John KD6OZH ----- Original Message ----- From: Juan Rivera To: 'John B. Stephensen' Cc: 'AMSAT Eagle' Sent: Sunday, June 10, 2007 22:17 UTC Subject: RE: [eagle] Latest 70 cm Receiver Test Results
John and group,
Questions:
1) What about the phase noise? I'm assuming that that big hump is phase noise. Do you consider that to be excessive?
2) What about the passband ripple? That needs to get fixed.
3) If the next generation of the radio is going to be autonomous, fixed tuned, and have continuous power, what exactly is the CAN-Do module doing except returning a few parameters to the IHU? It makes sense to me to get it away from the radio completely. You can feed it whatever it needs such as loop lock status and temperature. That also fixes our lack of front panel space problem.
Until question 3 is resolved it doesn't make any sense to me to spend the time necessary to desolder the CAN-Do module and relocate it. For now we can initialize the receiver and then kill the CAN-DO module (RFC10 id removed and the receiver is powered separately.) That will create the same conditions as perfect CAN-Do module isolation would without the work.
I'd like to get back to the ATP testing but until we have items 1 and 2 resolved and correct the microphonics, there isn't too much sense in starting the ATP now. I'll focus on the microphonics while you folks digest this latest information.
By the say, are there new specs for the receiver yet? Is it still expected to cold soak to -70C? That's close to the temperature of liquid CO2 and well below the storage temperature of most components and way below the operating temperature limits.
73,
Juan
WA6HTP
------------------------------------------------------------------------------
From: John B. Stephensen [mailto:kd6ozh@comcast.net] Sent: Sunday, June 10, 2007 12:51 PM To: juan-rivera@sbcglobal.net Cc: 'AMSAT Eagle' Subject: Re: [eagle] Latest 70 cm Receiver Test Results
The time that I spent optimizing the layout of the U17 switching regulator appears to be worth it if it isn't polluting the VCOs. What would be ideal is a module case where the CAN bus can exit from one side and the RF and IF from the other.
For now, the RF and IF can be run back to the connector bracket with SMA jumper cables. What is needed is a CAN-Do widget without the header connector so that wire leads can carry power and signals to the receiver PCB. 18-22 guage wire should work for power and 22-26 guage for signals. The wires need to be wound around a torroidal ferrite core to kill any common-mode noise. It may also be necessary to run the coax through ferrite beads. Do you have any beads or torroids made of material 75 or 77?
73,
John
KD6OZH
----- Original Message -----
From: Juan Rivera
To: eagle@amsat.org
Sent: Sunday, June 10, 2007 17:59 UTC
Subject: [eagle] Latest 70 cm Receiver Test Results
All,
As I troubleshoot the 70 cm receiver I stop and add to my logs every few minutes. I won't bother to announce every step I take (I just made an addition) because it takes too long. If you are interested please check the latest log at the top of the list or go to my web site. If you have a comment or suggestion just drop me an email via this Eagle/AMSAT mailer and everyone can participate. I'll check email often when I'm working on this project.
Here's the link to the AMSAT/Eagle receiver page --> http://www.amsat.org/amsat-new/eagle/EaglePedia/index.php/U-Band_Receiver
From there find the latest log at the top of the list under Project Status. At the moment it's 'Spur Troubleshooting'
Or...
Go to my web at http://www.juanr.com/
Select Amateur Radio, select AMSAT/Eagle, and select the log you want to see from the menu.
73,
Juan
WA6HTP
----------------------------------------------------------------------------
_______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
participants (7)
-
Dick Jansson-rr -
Grant Hodgson -
Jim Sanford -
John B. Stephensen -
Juan Rivera -
Robert McGwier -
Tom Clark, K3IO