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Re: PA Working!
by Burns Fisher (AMSAT) 13 May '24

13 May '24

DCT is "Digital Command Transponder" which makes about as much sense as IHU, but it's the Gofl name for the chip. That command can set two levels, I think, and each pair can be set for either safe mode or non-safe. In other words, you can set it so if golf is in safe mode, it will be either high or low, and also if it not in safe mode, it will be high or low. I don't remember what I did with the command on Pacsat. But look where in MRAM that command puts a value, and then search for the MRAM name in other places, and you can probably see what it does to change the power. 73, Burns Fisher, WB1FJ *AMSAT(R) Engineering -- Flight Software* On Mon, May 13, 2024 at 11:58 AM Bob Stricklin via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > We have a functioning PA. The final level is low at this point but that > should be a matter of running things. > > The input drive level is also very low. Is there a provision in the code > to turn adjust the drive level? > I see a command "Set dct drive power” but what is dct? I hope it the name > of the AX5043 register. > Also see “SELECT DCT POWER”. What does this do? > > I hope one of your knows the combination otherwise I can start looking at > the data sheet and manual for AX5043? > > The magic here has to do with the Vbias level on the LDMOS. I just copied > the example in the data sheet and they never talk about what the Vbias > level should be. > The level also sets up the quiescent current in the LDMOS and critically > biases the device. I took out the filtering and matching and just > capacitively coupled the input and output then tuned the > Vbias. The operate point is going to be about 2.9 volts to 3.4 Volts. at > 2.8 volts the Ids through the device is 100 ma and it goes up fast from > there. We will need a Ids of about 300 to get 2W operation. > > WE need to be thinking about turning on and off the supply voltage to the > PA when we transmit. This will save a lot of battery power and a heat > reduction. > > Currently when I turn the Vbias up to about 2.9 volts I get extra > oscillation. This should be eliminated by adding matching components back > in. I have included two images of the signals with and without the > oscillation. The level of output is about -40dBm with the current setup > and it is sending packets to the ground station fine. > > Photo of my setup for spectrum analyzer testing included. Using a stack of > attenuators on transmitter. The Rx antenna is two of the clip leads > together and clipped on Rx antenna. > > One thing to look for at Hamvention would be a low cost rubber ducky > antenna for 2M and 70cm. Either dual band or two singles. If we want to > keep spending money on this we could probably use 8 of these antennas. > > Bob N5BRG > > > > > > > > > > > > > > > > > > > > > ----------------------------------------------------------- > > pacsat-dev mailing list -- pacsat-dev(a)amsat.org > View archives of this mailing list at > https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org > To unsubscribe send an email to pacsat-dev-leave(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org >

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PA Working!
by Bob Stricklin 13 May '24

13 May '24

We have a functioning PA. The final level is low at this point but that should be a matter of running things. The input drive level is also very low. Is there a provision in the code to turn adjust the drive level? I see a command "Set dct drive power” but what is dct? I hope it the name of the AX5043 register. Also see “SELECT DCT POWER”. What does this do? I hope one of your knows the combination otherwise I can start looking at the data sheet and manual for AX5043? The magic here has to do with the Vbias level on the LDMOS. I just copied the example in the data sheet and they never talk about what the Vbias level should be. The level also sets up the quiescent current in the LDMOS and critically biases the device. I took out the filtering and matching and just capacitively coupled the input and output then tuned the Vbias. The operate point is going to be about 2.9 volts to 3.4 Volts. at 2.8 volts the Ids through the device is 100 ma and it goes up fast from there. We will need a Ids of about 300 to get 2W operation. WE need to be thinking about turning on and off the supply voltage to the PA when we transmit. This will save a lot of battery power and a heat reduction. Currently when I turn the Vbias up to about 2.9 volts I get extra oscillation. This should be eliminated by adding matching components back in. I have included two images of the signals with and without the oscillation. The level of output is about -40dBm with the current setup and it is sending packets to the ground station fine. Photo of my setup for spectrum analyzer testing included. Using a stack of attenuators on transmitter. The Rx antenna is two of the clip leads together and clipped on Rx antenna. One thing to look for at Hamvention would be a low cost rubber ducky antenna for 2M and 70cm. Either dual band or two singles. If we want to keep spending money on this we could probably use 8 of these antennas. Bob N5BRG [cid:711e5b75-5bc9-45a2-a24e-ba27a4f018af@namprd13.prod.outlook.com] [cid:bd342ec3-5a50-418d-82fa-46e51662ee43@namprd13.prod.outlook.com] [cid:95b5235b-9731-4568-8ea4-a6ae8af5c968@namprd13.prod.outlook.com]

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Re: Inductor Insertion
by Jim McCullers 12 May '24

12 May '24

Chis, Since you have Bob’s transformer mods you are good to go. Bob did a nice job on this mod, much better than what I did. Good luck, Jim McCullers WA4CWI Tha is for the pictures Bob. Do we need to make other changes as well? Is this in addition to the changes you made to the balun, or instead of them? Can you provide an updated schematic with the changes? Thanks 73 Chris On Sat, May 11, 2024, 13:20 Bob Stricklin via pacsat-dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsatorg> > wrote: 2 standing on there ends and on top of the capacitors. All 100 uh Bob ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to pacsat-dev-leave(a)amsat.org <mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org

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Re: Inductor Insertion
by Chris Thompson 12 May '24

12 May '24

Tha is for the pictures Bob. Do we need to make other changes as well? Is this in addition to the changes you made to the balun, or instead of them? Can you provide an updated schematic with the changes? Thanks 73 Chris On Sat, May 11, 2024, 13:20 Bob Stricklin via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > 2 standing on there ends and on top of the capacitors. > All 100 uh > > Bob > > > > ----------------------------------------------------------- > > pacsat-dev mailing list -- pacsat-dev(a)amsat.org > View archives of this mailing list at > https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org > To unsubscribe send an email to pacsat-dev-leave(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org >

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Inductor Insertion
by Bob Stricklin 11 May '24

11 May '24

2 standing on there ends and on top of the capacitors. All 100 uh Bob

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Log with RSSI readings
by Bob Stricklin 09 May '24

09 May '24

Log captured with all four receivers set for 145.840 to get common RSSI data. On the ground station log and the satellite log you can see for different transmission responding to a dir request. Bob

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Pacsat dev mtg 5/9/2024
by Bill 09 May '24

09 May '24

Pacsat dev mtg 5/9/2024 Thu, May 9, 2024 7:00 PM - 9:00 PM (CDT) Please join my meeting from your computer, tablet or smartphone. https://meet.goto.com/910630661 You can also dial in using your phone. (For supported devices, tap a one-touch number below to join instantly.) United States: +1 (571) 317-3112 - One-touch: tel:+15713173112,,910630661# Access Code: 910-630-661 Join from a video-conferencing room or system. Dial in or type: 67.217.95.2 or inroomlink.goto.com Meeting ID: 910 630 661 Or dial directly: 910630661(a)67.217.95.2 or 67.217.95.2##910630661 Get the app now and be ready when your first meeting starts: https://meet.goto.com/install

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Re: 4 RX devices now working!
by Jim McCullers 07 May '24

07 May '24

CONGRATS! There is some code in the receiver task RxTask that can be uncommented and will report all four RSSIs on each received packet. A bit of overkill but I used it to notice the two non-working AX5043s were essentially dead. I'll repeat your success when the regulator chip arrives. Jim WA4CWI All, I now have all four of the receivers working! The two in the center of the board did not have their inputs referenced to ground. Jim point this out and said he read that they needed to be ground referenced. So I placed a 100 nH inductor on all four of these input and connected it to Ground. I was carefully trying to keep the line length all balanced. When I tested the board all four were working. I have been moving the frequency around on each receiver. I found when two or more receivers are on the same frequency the satellite will respond to a request 2 or more times. When on individual frequencies then only one reply. I currently have the four at 145.840 .850 .860 .870 and they are all working indipendently. If I move the one at .870 up to .875 it stopes working. I tried to look at RSSI but i think I need to have data coming in when reading the RSSI value. I am going to look at this more later and capture all the register values. Bob ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to pacsat-dev-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org

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4 RX devices now working!
by Bob Stricklin 07 May '24

07 May '24

All, I now have all four of the receivers working! The two in the center of the board did not have their inputs referenced to ground. Jim point this out and said he read that they needed to be ground referenced. So I placed a 100 nH inductor on all four of these input and connected it to Ground. I was carefully trying to keep the line length all balanced. When I tested the board all four were working. I have been moving the frequency around on each receiver. I found when two or more receivers are on the same frequency the satellite will respond to a request 2 or more times. When on individual frequencies then only one reply. I currently have the four at 145.840 .850 .860 .870 and they are all working indipendently. If I move the one at .870 up to .875 it stopes working. I tried to look at RSSI but i think I need to have data coming in when reading the RSSI value. I am going to look at this more later and capture all the register values. Bob

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Re: Test Results after changing frequency
by Jim McCullers 07 May '24

07 May '24

Two out of two isn’t bad. The front end, especially for receiving, is open to interpretation. I’m not convinced the differential input has much impact on the noise immunity and SNR but that would be an interesting study. The differential is more for transmitter PA matching than high performance receiving. Hopefully the regulator will be in tomorrow and I can resume testing of the modified circuit. Jim McCullers WA4CWI All, Reviewing the boards this morning all four of the receivers have the same inductor. There could be a difference in tolerance creating different values in the registers. This could be checked by swapping the inductors. The traces on the board are similar in two cases and slightly different in two others. I now feel the issue with the two receivers that are not working is the matching circuit. I essentially had four different matching circuits on the board for testing. Two of the circuits are working and two are not. May be able to get the two non-working units up by changing the components or restructuring the interface. This would allow testing with all four Rx devices. My original idea was to experiment with differential inputs to try and improve noise immunity and increase SNR. Bob From: Burns Fisher (AMSAT) <wb1fj(a)fisher.cc <mailto:wb1fj@fisher.cc> > Sent: Tuesday, May 7, 2024 6:49 AM To: Bob Stricklin <bstrick(a)n5brg.com <mailto:bstrick@n5brg.com> > Cc: Jim McCullers <wa4cwi(a)bellsouth.net <mailto:wa4cwi@bellsouth.net> >; Pacsat Dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > Subject: Re: [pacsat-dev] Re: Test Results after changing frequency Oops. Well I got 91 and nano right. 73, Burns Fisher, WB1FJ AMSAT(R) Engineering -- Flight Software On Mon, May 6, 2024 at 11:12 PM Bob Stricklin via pacsat-dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > wrote: Jim, This could be an issue. I will look at it more. Sorry you having trouble with the voltage regulator. Hope you get it fixed without much trouble. I am keeping the PCB in the 3D printed case with the covers off for probing here and have not had any issues here so far. I take the board out to solder if needed. Bob On May 6, 2024, at 9:36 PM, Jim McCullers via pacsat-dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > wrote: Not capacitor. Inductor. L301 on receiver 2, L201 on receiver 1. I was half paying attention this afternoon, read the 91 and kept going. It’s 91nf and something is required there for VHF, the actual value will determine the range which I believe to be the weakest idea on the chip. I assume they had reason. For higher frequencies like 70cm the inductor can be shorted. My belief is the problem is in the front end circuit and I had completed modifying receiver 2 and headed for the test bench when I bonked the regulator. Should be in Wednesday as I bought it a higher class ticket. Jim From: Burns Fisher (AMSAT) via pacsat-dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > Sent: Monday, May 6, 2024 9:26 PM To: Bob Stricklin <bstrick(a)n5brg.com <mailto:bstrick@n5brg.com> > Cc: Pacsat Dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > Subject: [pacsat-dev] Re: Test Results after changing frequency I thought it would not range at 2m without the capacitor. But I'm far from an expert! 73, Burns Fisher, WB1FJ AMSAT(R) Engineering -- Flight Software On Mon, May 6, 2024 at 10:16 PM Bob Stricklin via pacsat-dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > wrote: Burns, I do not have a 91nF cap around the Rx devices. Perhaps this is used on another project? I will look at the clock input on each of the Rx devices with a scope to see if there is any issue with clocking inputs. The clocks are all being feed from a buffer driver with a 16 MHz clock with Clock 1 signal being feed to two Rx devices one of which is working and one not. Bob On May 6, 2024, at 2:11 PM, Jim McCullers via pacsat-dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > wrote: I’m not certain how the ranging process works as to what it leaves in the PLL values but it is affected by the range capacitor (91nF or whatever) as well as board and circuit stray capacitance so that is a possibility. The purpose of ranging is to align the PLL correctly. I spent time this weekend doing what Bob did, taking measurements and reviewing the circuits. Part of the time was using a $29 eBay phase detector I purchased to measure the actual phase out of the transformers. At the moment no ready to give it a 5 out of 5 and am struggling for a 1. It uses a Analog Devices chip that apparently goes to 2.8g but the device appeared to struggle at 146mhz and no phase change from input to no input. I find it difficult to think it is in the code as it’s all load and go but …. And in the process of moving the board between the work bench and the test stand I banged the LM1117 regulator and broke a lead at the body. Digi-Key has one on the way. I do solemnly swear to never work on this board on a Saturday night. That’s two for two power supply problems and I know the source for at least one if not the other. I’ve done my verification work and have a couple ideas to try when the chip arrives (I bought two to quell the demons). Jim Is it possible that this relates to differences in the 91nF capacitors? E.g. that either the caps differ or there is some different capacitance in in the area on the board or something? I just remember that the ranging seemed to differ some from board to board. Maybe from chip to chip too? 73, Burns Fisher, WB1FJ AMSAT(R) Engineering -- Flight Software On Mon, May 6, 2024 at 2:44 PM Bob Stricklin via pacsat-dev <pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> > wrote: I went through a series of test using the instructions provided by Bruns for hanging the frequency. When i placed 3 of the four AX5043 devices on 145.840 MHz I could mostly only copy signals on Device 2. Occasionally Device 3 would come through also but it is supposed to be set on 145.870 MHz. Then I placed all four devices on 145.840 and again mostly only Device 2 is copied but occasionally Device 3 would be copied. Then I moved the frequency setting on device 2 and 3 off of 145.840 to 145.890. At that point occasionally Device 3 would copy the signals. Using a spectrum analyzer I checked the signal coming into each one of the AX5043 inputs and found the levels to be about the same on all devices. May need to do more testing by forcing interrupt on the parts not responding if possible. I think I recall Chris indicating he did see interrupts coming back from all four devices. With the AX5043 devices all set at 145.840 I see different values in the PLL registers. This seems odd to me. I am attaching logs for my testing this morning. I plan to spend some time looking over the layout for each AX5043 to make sure they all match except for Device 2. When I first started this morning the frequency for one of the devices was 145.860 MHz. I did change the values in config.h file and I had issues an "init new proc" and a "pre flight init" yesterday trying to get the config.h frequencies in place. There are some minor issues which may be addressed later but not a problem on debug. There may be a bug in the AX5043 code however. Bob ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to pacsat-dev-leave(a)amsat.org <mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org <https://mailman.amsat.org/> ----------------------------------------------------------- pacsat-dev mailing list -- <mailto:pacsat-dev@amsat.org> pacsat-dev(a)amsat.org View archives of this mailing list at <https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org> https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to <mailto:pacsat-dev-leave@amsat.org> pacsat-dev-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at <https://mailman.amsat.org/> https://mailman.amsat.org ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to pacsat-dev-leave(a)amsat.org <mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org <https://mailman.amsat.org/> ----------------------------------------------------------- pacsat-dev mailing list -- <mailto:pacsat-dev@amsat.org> pacsat-dev(a)amsat.org View archives of this mailing list at <https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org> https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to <mailto:pacsat-dev-leave@amsat.org> pacsat-dev-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at <https://mailman.amsat.org/> https://mailman.amsat.org ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org <mailto:pacsat-dev@amsat.org> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to pacsat-dev-leave(a)amsat.org <mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org

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