(tr)uSDX power, efficiency and filter optimisation

Post Reply
DL2MAN
 

Posts: 706
Joined: 30 Dec 2021, 19:18
Contact:

Re: (tr)uSDX power, efficiency and filter optimisation

Post by DL2MAN »

SA4DHT wrote: 02 Apr 2022, 10:57 There is a mismatch between schematic/BOM and the table with L and C values for the different transistors and frequencies. For 20 m schematic/BOM for C10//C11 is 68 pF in the table for 3 x BS170 it says 128 pF for 20 m and CX0//CX1.
It´s exhausting explaining this over and over again....
viewtopic.php?p=2090#p2090
Everyone seems to figure out, there´s a difference, but noone seems to read why.

And I´m repeating myself again as response to all the other suggestions:
The first thing I did was checking if the OnBoard measurement was accurate. It was in my case.
All caps have been exchanged
All Toroids have been exchanged
Relay has been exchanged
FETs have been exchanged
SMA Connector has been exchanged
In the Last Step even the Ferrite Toroids (Black ones) have been exchanged

None of those actions increased efficiency.
So what´s left here ?

And yes, If I use the *Rxxxx* Mainboard with another RF Board, it works in the 80% PLus Efficiency Region.

Please read the whole thread before posting so we do not need to repeat and repeat and repeat.


I don´t think *Rxxxx* sells bad things on purpose. As far as I know they don´t deliver at the moment.
For obvious reasons they did not get approval, and right now we´re in an ongoing investigation why. But I am out of ideas and spent already too much time and money to consider continuing. (Remember: I do this for free in my free time, I am not involved in any sales while others benefit from my work and money) Now others have to chime in, especially *Rxxxx* would benefit most to investigate this in depth. I assume they do.

73 Manuel; DL2MAN
S53SL
 

Posts: 9
Joined: 31 Mar 2022, 21:24

Re: (tr)uSDX power, efficiency and filter optimisation

Post by S53SL »

John wrote: 01 Apr 2022, 02:27 Off subject, but it looks to me like you have 8 turns on T1. The magic number is 7.
You are right! I've made a mistake.

Unfortunately it didn't solve the problem.
The measurement is also jumping a bit especially in beginning, as it did before. Sometimes it shows 99.99% and 12W and when I press PTT couple of times it settle down to around 2W.

I've noticed that also one of the FETs is heating up when I just power it up without transmitting. It seems it's also failure somewhere else. I will try to replace this FET.
Attachments
Thermal camera
Thermal camera
IMG_20220402_131441.jpg (58.56 KiB) Viewed 10422 times
73 de S53SL
S53SL
 

Posts: 9
Joined: 31 Mar 2022, 21:24

Re: (tr)uSDX power, efficiency and filter optimisation

Post by S53SL »

Replacing FET (Q3) was very hard as one pad is ground and it was very hard to unsolder it in first place and then it was very hard to unclog the through hole. Ground plane probably dissipate too much heat. I probably spend half an hour just trying to replace the FET. And that failed also as now output power is 0.2W. :cry:

It might still be problem with transistors, as I found some BS170 at home, that I probably bought one day via Aliexpress, so they might be fake ones.
So I guess I will have to go to elections shop in monday to buy some genuine ones... hopefully.

I guess it will again take some time to replace all of them. Hopefully I won't destroy PCB traces in the process.

It might be problem also somewhere else in the line, but I'm not sure where. Only component that I saw that was heating too much was linear regulator (U2).
73 de S53SL
SA4DHT
 

Posts: 19
Joined: 10 Jan 2022, 14:13

Re: (tr)uSDX power, efficiency and filter optimisation

Post by SA4DHT »

After changing C12, C16, C19 to NP0 efficiency went up from 48 to 63% and output power to about 5W. Not sure if the caps I found in my hidings caps are 50V or 100V they still get a bit hot and voltage is about 50Vp-p. Will order low ESL from Digikey and check again.

Anyhow audio improved a lot after this change too and I made the first QSO with this little amazing rig and a 200W station in Genua/ Italy.

73 de Dirk SA4DHT

P.S It is a batch 3 board from *Rxxxx* and biggest problem are the caps it seems D.S
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: (tr)uSDX power, efficiency and filter optimisation

Post by Ohwenzelph »

To unclog the plated thru hole, consider using a sewing needle, a shiny one that solder does not stick to easily. You have to place it really fast. Gently get it back out. Good if you have some clamping forceps to hold it with. You don't have to completely open the hole, only enough to be able to get the lead through. Repeatedly overheating and having the trace delaminate from the board is no fun. If you need to open it wider, sometimes some flux and solder wick will finish the job. Might have to work it from both sides. Sometimes a solder sucker will work well but lately I have been using a sewing needle most often.
73
om0wt
 

Posts: 5
Joined: 25 Mar 2022, 08:51

Re: (tr)uSDX power, efficiency and filter optimisation

Post by om0wt »

DL2MAN wrote: 01 Apr 2022, 07:31
John wrote: 01 Apr 2022, 02:27

Off subject, but it looks to me like you have 8 turns on T1. The magic number is 7.
That´s not off topic, that´s a big fat BINGO !
Guys, how many turns do you see here? 7 or 8? I see 8...
T1turns.jpg
T1turns.jpg (176.91 KiB) Viewed 10274 times
I have a problem with very high efficiency and output power values too...

73, Pavol OM0WT
AC9YY
 

Posts: 133
Joined: 21 Mar 2022, 00:04
Location: Illinois, USA

Re: (tr)uSDX power, efficiency and filter optimisation

Post by AC9YY »

om0wt wrote: 03 Apr 2022, 21:30
DL2MAN wrote: 01 Apr 2022, 07:31
John wrote: 01 Apr 2022, 02:27

Off subject, but it looks to me like you have 8 turns on T1. The magic number is 7.
That´s not off topic, that´s a big fat BINGO !
Guys, how many turns do you see here? 7 or 8? I see 8...

T1turns.jpg

I have a problem with very high efficiency and output power values too...

73, Pavol OM0WT
T1 looks okay to me, but it looks like T2 only has 6 instead of 7 turns. Hard to be certain with the direction the photo was taken from.

73, Jim AC9YY
om0wt
 

Posts: 5
Joined: 25 Mar 2022, 08:51

Re: (tr)uSDX power, efficiency and filter optimisation

Post by om0wt »

AC9YY wrote: 03 Apr 2022, 21:48
om0wt wrote: 03 Apr 2022, 21:30
DL2MAN wrote: 01 Apr 2022, 07:31

That´s not off topic, that´s a big fat BINGO !
Guys, how many turns do you see here? 7 or 8? I see 8...

T1turns.jpg

I have a problem with very high efficiency and output power values too...

73, Pavol OM0WT
T1 looks okay to me, but it looks like T2 only has 6 instead of 7 turns. Hard to be certain with the direction the photo was taken from.

73, Jim AC9YY
Here's better view of T2:
T2.jpg
T2.jpg (136.89 KiB) Viewed 10268 times
AC9YY
 

Posts: 133
Joined: 21 Mar 2022, 00:04
Location: Illinois, USA

Re: (tr)uSDX power, efficiency and filter optimisation

Post by AC9YY »

om0wt wrote: 03 Apr 2022, 22:01
AC9YY wrote: 03 Apr 2022, 21:48
om0wt wrote: 03 Apr 2022, 21:30

Guys, how many turns do you see here? 7 or 8? I see 8...

T1turns.jpg

I have a problem with very high efficiency and output power values too...

73, Pavol OM0WT
T1 looks okay to me, but it looks like T2 only has 6 instead of 7 turns. Hard to be certain with the direction the photo was taken from.

73, Jim AC9YY
Here's better view of T2:

T2.jpg
I only see 6 turns on T2, which would explain your readings being off.
jeremylaratro
 

Posts: 18
Joined: 07 Feb 2022, 16:33

Re: (tr)uSDX power, efficiency and filter optimisation

Post by jeremylaratro »

Has anyone tried taking a *Rxxxx* kit, reburning the bootloader properly, reloading the software, and then testing efficiency? Maybe they are using the normal Arduino bootloader? Or, try swapping a new ATMEGA?
KO4DNM
va3rr
 

Posts: 54
Joined: 30 Dec 2021, 21:39
Location: FN25eg
Contact:

Re: (tr)uSDX power, efficiency and filter optimisation

Post by va3rr »

jeremylaratro wrote: 04 Apr 2022, 23:29 Has anyone tried taking a *Rxxxx* kit, reburning the bootloader properly, reloading the software, and then testing efficiency? Maybe they are using the normal Arduino bootloader? Or, try swapping a new ATMEGA?
Manuel has connected one of his RF Boards to a *Rxxxx* mainboard, and the efficiency is high.

viewtopic.php?p=2200#p2200
Slava Ukraini!
hb9hem
 

Posts: 36
Joined: 07 Jan 2022, 04:39

Re: (tr)uSDX power, efficiency and filter optimisation

Post by hb9hem »

All caps have been exchanged
All Toroids have been exchanged
Relay has been exchanged
FETs have been exchanged
SMA Connector has been exchanged
In the Last Step even the Ferrite Toroids (Black ones) have been exchanged

None of those actions increased efficiency.
So what´s left here ?
All I can think of is: Bad PCB. But I can't quite imagine how different batches can come out with the same defect(s).
Another possibility, a really annoying one, would be that too many components are somewhat off-spec resulting in a cascade of negative effects.
jeremylaratro
 

Posts: 18
Joined: 07 Feb 2022, 16:33

Re: (tr)uSDX power, efficiency and filter optimisation

Post by jeremylaratro »

Just an FYI -- something which may make tuning the RF Boards a bit easier.
Theres a software called AntScope which connects to the NanoVNA and allows you to set the system impedance. So you can set it to 10ohms and work on the fundamental frequency using this.
I haven't tried it yet but am planning on doing this when I get a chance to make another RF board for the upper bands.

https://rigexpert.com/products/software ... antscope2/
Last edited by jeremylaratro on 05 Apr 2022, 04:28, edited 2 times in total.
KO4DNM
jeremylaratro
 

Posts: 18
Joined: 07 Feb 2022, 16:33

Re: (tr)uSDX power, efficiency and filter optimisation

Post by jeremylaratro »

va3rr wrote: 05 Apr 2022, 00:03
jeremylaratro wrote: 04 Apr 2022, 23:29 Has anyone tried taking a *Rxxxx* kit, reburning the bootloader properly, reloading the software, and then testing efficiency? Maybe they are using the normal Arduino bootloader? Or, try swapping a new ATMEGA?
Manuel has connected one of his RF Boards to a *Rxxxx* mainboard, and the efficiency is high.

viewtopic.php?p=2200#p2200
In that case, reloading the bootloader and firmware onto a *Rxxxx* mainboard is definitely worth a shot. I have personally seen strange efficiency issues when testing different settings on my experimental boards, as well as some corruption in the firmware where the efficiency shows 0% but clearly is not.
KO4DNM
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: (tr)uSDX power, efficiency and filter optimisation

Post by Ohwenzelph »

While trying to find values for good power and efficiency:
Sometimes when I press PTT instead of "2.41 watts 38%" it will say something like "13.51 watts 99.99%"
What's happening and what causes this? I assume it's going into some kind of oscillation perhaps? On occasion I have noted at least one of the pa fets is warm after this.
Thanks
hb9hem
 

Posts: 36
Joined: 07 Jan 2022, 04:39

Re: (tr)uSDX power, efficiency and filter optimisation

Post by hb9hem »

Sometimes when I press PTT instead of "2.41 watts 38%" it will say something like "13.51 watts 99.99%"
This happens to me, too, sometimes, and the problem always went away after tightening the SMA connector.
6k2kus
 

Posts: 8
Joined: 19 Mar 2022, 02:14

Re: (tr)uSDX power, efficiency and filter optimisation

Post by 6k2kus »

I was adjusting the LX2 following Manuel's video.

1. My notch in the logmag curve is not as deep (-45 dB) and steep as that in the video (and here). Can someone help me achieve the depth?

2. Also does the location of a dip in the logmag curve of S11 (not S12) give some information, e.g. the fundamental resonance? My second dip doesn't have the 2x frequency of the fundamental. Can we adjust it separately?

3. Sorry for repeating the question. Did we test the capacitors in the pi filter? I saw some comments about the necessity high voltage tolerence cap. Clearly this is also the difference between kits. The chinese kit has thick ones while *Rxxxx* kit has thin ones.
hb9hem
 

Posts: 36
Joined: 07 Jan 2022, 04:39

Re: (tr)uSDX power, efficiency and filter optimisation

Post by hb9hem »

Did we test the capacitors in the pi filter?
Top
Have a look at Manuel's post from 02 Apr 2022, 13:21.
DL3MHT
 

Posts: 21
Joined: 14 Mar 2022, 09:46

Re: (tr)uSDX power, efficiency and filter optimisation

Post by DL3MHT »

Apologies if this is a dumb question and/or I did not find the correct thread.
I somehow missed the ballpark figures of what we like to see.

What is the power and efficiency range we are aiming for?
Something between 4.5 - 5.5W on every band with an efficiency of 80% or higher?

Thanks,
Tobias
hb9hem
 

Posts: 36
Joined: 07 Jan 2022, 04:39

Re: (tr)uSDX power, efficiency and filter optimisation

Post by hb9hem »

What is the power and efficiency range we are aiming for?
See this post.
"Something between 4.5 - 5.5W on every band with an efficiency of 80% or higher" - that sums it up.
SA4DHT
 

Posts: 19
Joined: 10 Jan 2022, 14:13

Re: (tr)uSDX power, efficiency and filter optimisation

Post by SA4DHT »

SA4DHT wrote: 02 Apr 2022, 09:54 I have a kit from *Rxxxx* batch 3. I am facing the same issues regarding efficiency as others have reported at 12 V in:
20 m 3.8W 45.7%
30 m 3.4W 50.0%
40 m 2.7W 50.5%
60 m 2.6W 51.5%
80 m 3.8W 51.1%

Started to check 20 m with a high resolution thermal camera and find C12, C19 and C16 getting very hot about 70 deg C. So there energy is wasted. I will try to replace them. I have NP0 here but not sure if they are 50V or 100V. Another question is how the target capacitance is achieved on good versus bad board. Wrong type and voltage is one possibility another if one or two capacitors are used per position in order to get the goal capacitance. MOSFET BS170 are getting hot too at about 40 deg C one beeing at higher temperature so current sharing is not perfect. T2 is getting hot too about 40 deg C. On one of the videos Manuel has posted it seems to me T1 and T2 are winded with bigger diameter wire than 0.4 mm.
In order to solve the above situation on my batch 3 from *Rxxxx* kit:

1) Checked the internal efficiency calculation and found it about 10% too low compared to measuring with external instruments. Measured the trace used as current shunt with a Keithley 197 and found it to be 19 mOhm instead of 17 mOhm as set as default in 8.6 R Shunt. A appropriate instrument is needed in order to measure such low resistances!

2) Ordered Kemet C0G 0805 100V 5% low ESL capacitors and replaced all bandfilter capacitors.

Results after that at 12V in:

20 m 3.09W 68.67%
30 m 3.78W 77.35%
40m 3.23W 80.75%
60m 3.38W 80.48%
80m 6.00W 82.78%

2nd harmonic looks good on all bands. I might try to trim the LX1 toroids to adjust power a little bit, but on 13.8V in I have more than 4W on all bands. U9 is a LM833 and works ok but sideband suppression could be better. Noise is about S3 even with a dummy load on all bands.
I have made some QSOs and I am getting good reports. Audio seems to be ok even using the internal mic.

Hope this is useful.

73 de Dirk
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: (tr)uSDX power, efficiency and filter optimisation

Post by Ohwenzelph »

Been trying to get a hi band set up working and have had no luck finding the right values for good efficiency. The old nanovna broke, used an antuino to tweak the harmonic coils. Got a new nanovna, followed Manuel's video, built a 1:4 impedance transformer to bring 12.5 ohms up to 50 ( but is it really 10 up to 40?..). You have to use a barrel connector at the ends of the cables to cal the nanovna so the cal maybe slightly off. Working on that. Have made many substitutions but either there is nearly no change or it's worse! My best oscillascope is a 2 chanel 50MHz Tektronix 453
With the lowest frequency, 20 meters, rf on top and drv below
691E6664-9121-48F7-A68D-341FE65073EE.jpeg
691E6664-9121-48F7-A68D-341FE65073EE.jpeg (76.81 KiB) Viewed 9734 times
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: (tr)uSDX power, efficiency and filter optimisation

Post by Ohwenzelph »

Looking for the "practical" values for the higher bands: not there, still looking...
NH group buy. AtMega from an UNO R3. Opamp LMH6622 so added 82k resistors.
12 volts. Currently this is what I get. I have not verified the power and efficiency. Some times I could not exactly match things that should be equal. These are the values that i think are on the board right now, if i didn't lose track... Caps are all npo and at least 100 volts, the toroids are genuine.
Often the power and efficiency drop if I keep the key down and i suspect that is bad and guess it's fets heating up.
(Meters watts percent components)

20 4.4 58% 68, 478, 7t 37-7 bunched some, 477, 8t 37-6 even spread, 470, 151

17 4.2 61% 121, 378, 7t 37-6 even spread, 382, 7t 37-6 gap at bottom, 387, 120

15 3.8 60% 100, 325, 8t 37-6 even spread, 330, 6t 37-6 bunched, 330, 100

12 3.5 49% 90, 268, 6t 37-6 even spread, 272, 5t 37-6 tight bunch, 272, 88

10 3 44% 69, 236, 6t 37-6 even spread, 233, 5t 37-6 bunched, 233, 78

Does anyone know what to do with 20 based on what the scope traces showed? I have looked at the QEX article. It's not clear to me.
AC9YY
 

Posts: 133
Joined: 21 Mar 2022, 00:04
Location: Illinois, USA

Re: (tr)uSDX power, efficiency and filter optimisation

Post by AC9YY »

Ohwenzelph wrote: 10 Apr 2022, 17:42 Looking for the "practical" values for the higher bands: not there, still looking...
NH group buy. AtMega from an UNO R3. Opamp LMH6622 so added 82k resistors.
12 volts. Currently this is what I get. I have not verified the power and efficiency. Some times I could not exactly match things that should be equal. These are the values that i think are on the board right now, if i didn't lose track... Caps are all npo and at least 100 volts, the toroids are genuine.
Often the power and efficiency drop if I keep the key down and i suspect that is bad and guess it's fets heating up.
(Meters watts percent components)

20 4.4 58% 68, 478, 7t 37-7 bunched some, 477, 8t 37-6 even spread, 470, 151

17 4.2 61% 121, 378, 7t 37-6 even spread, 382, 7t 37-6 gap at bottom, 387, 120

15 3.8 60% 100, 325, 8t 37-6 even spread, 330, 6t 37-6 bunched, 330, 100

12 3.5 49% 90, 268, 6t 37-6 even spread, 272, 5t 37-6 tight bunch, 272, 88

10 3 44% 69, 236, 6t 37-6 even spread, 233, 5t 37-6 bunched, 233, 78

Does anyone know what to do with 20 based on what the scope traces showed? I have looked at the QEX article. It's not clear to me.
Your power output is not bad for the higher bands, I thought they would drop as frequency went up. Since you started with a *Rxxxx* (tr)uSDX I wonder if those efficiency readings are correct or not. Someone with the same kit had to change the R Shunt to 19 to get it to read right, although that is not what Manuel saw.
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: (tr)uSDX power, efficiency and filter optimisation

Post by Ohwenzelph »

NH group buy, not *Rxxxx*. The power does seem to drop a little as frequency increases.
Last edited by Ohwenzelph on 10 Apr 2022, 23:42, edited 1 time in total.
Post Reply

Users browsing this forum: No registered users and 3 guests