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AX5043 Info
by Bob Stricklin 23 May '24

23 May '24

Here is a very nice posting by a 3rd party on setup of the AX5043. Everything is explained well. Some discussion on an analog mode near the bottom. https://www.notblackmagic.com/bitsnpieces/ax5043/ I still only see 0 dBm out of the AX5043. I do not have power register turned up all the way so I will try that next. I tried to post a software issue on get hub which included may code routine but this did not post properly. I am going to try again with a simpler issue. Still having some problem uploading things with going through a big ordeal here. I have corrections to code i will be trying to post later today. Bob

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I'm back from Dayton
by Bill Reed 22 May '24

22 May '24

Meeting this Thursday. Bill

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RevD Schematic
by Bob Stricklin 22 May '24

22 May '24

I pushed up a copy of the RevD schematic under PacSatDocs->Hardware. This is not complete or finished but does have the changes I have been working with here relating to the PA and other fixes. I am currently biasing the gate of the PA with an external voltage supply set to 2.7 volts and 100 mA. This can be done with a voltage divider and a voltage reference later. Tenths of a volt mater here so best to have a good reference in the long run. This node pulls almost no current. The drain supply and current are setup by using a 50 ohm resistor in series with the 5V regulator. I see the voltage has dropped to about 4.9 volts due to series inductor and trace resistance. This can be improved on the next PCB layout. There is about 3 volts on the drain with this combination and the resulting overall current low enough so the current monitor MAX4995 does not shut things down when set to its max of 600 mA. This may need to be eliminated when we push for more power and get the drain bias up to 5V. More testing is needed. The gate is being driven with about 0 dB or RF and the AX5043 is capable of 16dBm according to the data sheet. There is currently a filter in this circuit to reduce harmonics which may need to be eliminated or optimized to get the power level up on the gate of the PA. The final output filter is doing a good job of stopping harmonics. However feeding harmonics into the PA can cause some heating and power loss. Having the TMS570 switch the PA power on only when transmitting will result in some power savings. When on the PA will have a substantial bias current. Some delay for power to settle may be needed. My goal here was to document my thought and work. Bob

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PacSatSW
by Bob Stricklin 21 May '24

21 May '24

I just did a manual update from my MAC which has a key file for GitHub login. Should be fine with updated files. I need to add a keyhole to the linux computer I am using to see if thet allow CCS to work. Bob

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Code is working
by Bob Stricklin 21 May '24

21 May '24

I now have the code turning the Rx and Tx LEDs on and off. Rx is always on now. Also should have PA power working but need to add the blue wires to this PCB. I will work on pushing code up to GitHub. Bob

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Coding issue
by Bob Stricklin 21 May '24

21 May '24

I am having trouble getting the PA power and LEDs to switch the way I want. The most important code to me is in the tasked.c routine. This is were I am trying to do the power control and LED1 switching. I tried to PUSH my project into pacsatSW but apparently do not have permission to do so. Can this be changed? I raised an issue in issues and pasted my code in the issue. I would appreciate it if one of you can have a look and tell me what may fix the problem. My code is flagged with date 240519 N5BRG I have similar code blinking the LED3 for a heartbeat in interfaces->MET.c and this is working fine. Bob

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Re: Progress
by Chris Thompson 18 May '24

18 May '24

Very good Bob, sounds great. 73 Chris On Sat, May 18, 2024, 10:43 Bob Stricklin via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > I have the ability to make the power out of the AX5043 what I want it to > be thanks to the good suggestions. > > When I turn it up to max power I am seeing 0 dBm into the PA. At this > point the PA has 5 dBm out. To get to 2W we need 33 dBm to be at 2W however > we the amp would need to be higher by about 1 or 2 dBm to overcome the loss > of the final filter. I do have the PA held back by limiting its current and > only applying 5V and this time. I want to see the input side working > properly > before turning this up. I also want to change the code to allow the 5V be > turned on only when there is a need to send packets. Otherwise, the PA > continues to draw idle current and even though > the voltage drop is low there can be some heating. Eventually we will need > to look at the duty cycle of the PA and may need to plan on some sort of > heat sink/spreader which gets complicated > on a satellite. > > I am changing the LEDs to have one LED blink with a heart beat and one > each for TX and RX activity. > > There is no oscillations on PA at this point and the second harmonic is > not showing up past the filter at all. This is good news. > > Supply current goes up from 260 mA to about 360 mA when PA is active. This > will increase when we get more PA power output. > > I am working on the code to do power control and operate the LED. I have > one LED operating now and I see where to turn on TX LED. Bot TX and RX LEDs > can be controlled as part of the > interrupt routines coming from the AX5043 I believe. > > 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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Progress
by Bob Stricklin 18 May '24

18 May '24

I have the ability to make the power out of the AX5043 what I want it to be thanks to the good suggestions. When I turn it up to max power I am seeing 0 dBm into the PA. At this point the PA has 5 dBm out. To get to 2W we need 33 dBm to be at 2W however we the amp would need to be higher by about 1 or 2 dBm to overcome the loss of the final filter. I do have the PA held back by limiting its current and only applying 5V and this time. I want to see the input side working properly before turning this up. I also want to change the code to allow the 5V be turned on only when there is a need to send packets. Otherwise, the PA continues to draw idle current and even though the voltage drop is low there can be some heating. Eventually we will need to look at the duty cycle of the PA and may need to plan on some sort of heat sink/spreader which gets complicated on a satellite. I am changing the LEDs to have one LED blink with a heart beat and one each for TX and RX activity. There is no oscillations on PA at this point and the second harmonic is not showing up past the filter at all. This is good news. Supply current goes up from 260 mA to about 360 mA when PA is active. This will increase when we get more PA power output. I am working on the code to do power control and operate the LED. I have one LED operating now and I see where to turn on TX LED. Bot TX and RX LEDs can be controlled as part of the interrupt routines coming from the AX5043 I believe. Bob

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Not there tonight
by Corey Minyard 17 May '24

17 May '24

This is the Thursday I can't make it. -corey

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Re: PA Working!
by Chris Thompson 14 May '24

14 May '24

The power was set very low for bench testing. I put an extra hard coded call to set the register in the TxTask: radio_set_power(0x020); // minimum power to test You can change that line to update the tx power for testing. As Burns said, this all needs to be connected back to commands from the ground, stored in the telemetry etc. 73 Chris On Mon, May 13, 2024, 21:34 Bob Stricklin via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > Thanks Jim. > > Bob > > > On May 13, 2024, at 7:39 PM, Jim McCullers via pacsat-dev < > pacsat-dev(a)amsat.org> wrote: > > The power level is set by registers TXPWRCOEFFE0 and TXPWRCOEFFE1 (0x171 > and 0x170). > The range is 0 to 4095 (0x0fff) with 4095 representing maximum power. > > The documentation leads one to believe the relationship is linear but that > is not the case. > The power level follows a curve best described in the attached document. > See figure 1. > There is no way that I know to write an equation to set a desired level > and a table lookup is required. > The only given is 4095 (0xfff) represents max power, about +17dbm. The > low range is about -10dbm if I recall. > > Jim McCullers > WA4CWI > > > > > 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 > > > > > > > > > > > > <image001.jpg> > > > > <image002.jpg> > > > > <image003.jpg> > > > > > ----------------------------------------------------------- > > 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 > > <AX5043_AND9314-D_Power Analysis.PDF> > ----------------------------------------------------------- > > 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 > > > > ----------------------------------------------------------- > > 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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