Re: RA8875 display problems with T4.x - a visual study
I believe the ferrite sleeves made for the ribbon cable solved all my issues.
Tim W4YN
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T41 T41EEE.9 Firmware Release
T41EEE.9 is here:
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The README has all of the details.? This firmware is for the V10/V11 and T41-2 series platforms only.
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There were a lot of changes!? There will be bugs!? Please report them here.
I'm expecting graphics bugs.? These are hard to test for.? Primary radio functionality should be less buggy.
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Your feedback is requested!? Especially bug reports.? Please let me know, good or bad, thank you!
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--
73 Greg KF5N
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Re: RA8875 display problems with T4.x - a visual study
On Wed, Mar 26, 2025 at 10:37 AM, ken WA2MZE wrote:
it's not too difficult to split the wires, reorder them and then hold them in place with a small bit of tape, and then crimp
Good to know.? I used the following order:
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1. SCLK (gray)
2. GND (white)
3. VCC (black)
4. CS (brown)
5. VCC (red)
6. MISO (orange)
7. GND (yellow)
8. MOSI (green)
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Re: RA8875 display problems with T4.x - a visual study
Can you show how you re-ordered the cable?
If you have the "rainbow" type Insulation Displacement cable and raw connectors it's not too difficult to split the wires, reorder them and then hold them in place with a small bit of tape, and then crimp.? I've done this on floppy disk cables in the past.
I'd like to know the specific re-order that you used which worked.
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Re: boards and kits and stuff
I worked for Blackberry, and was privy to some of the hardware details.? They used I2C for most of the interchip connections.? I think the display interface was "bare metal" built into the SOC chips.? I2C can run at speeds up to 1mbs, though most common devices drop out at 400kbs.
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You should be okay now.
Jack, W8TEE
On Wednesday, March 26, 2025 at 12:14:55 PM EDT, Steven Fisher via groups.io <steven.fisher47@...> wrote:
I've sent a message several times asking about the digital post processor that was in the book "microcontroller s for amateur radio" and have gotten no response so no need for me to belong to the group....
Steve?
-- Jack, W8TEE
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Re: T41 V12 Boards and K9HZ Kits in stock
He is also a member here, but the above site is his own and a sure way to get his attention.
Jack, W8TEE
On Wednesday, March 26, 2025 at 12:14:57 PM EDT, Tom Schulte via groups.io <tomschulte9@...> wrote:
Bill,
? ? ? ? ?Would like to order 4-encoder boards and 2- Teensy Offset boards and 20A Power Distribution kit. How do you take payments and shipping cost to zip code 53132.
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? Tom AB9EK
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E-mail; call @arrl.net
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-- Jack, W8TEE
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Hi Tom:
For some reason, the site has rejected the last 4 applications for membership and I cannot see why. Also, the posts were sent to my Spam folder...again, don't know why. I think I have corrected this, but if you're having issues, contact me off site and we'll work to fix it.
Jack, W8TEE
On Wednesday, March 26, 2025 at 12:15:32 PM EDT, Tom Schulte via groups.io <tomschulte9@...> wrote:
I have asked for some help and to purchase some boards through this site. I have not seen my posts or have a reply to them. Am I being black balled? If that's the case would someone please let me know.
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Tom AB9EK
-- Jack, W8TEE
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Re: boards and kits and stuff
Here are the ferrite sleeves I use.
Tim W4YN
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Re: boards and kits and stuff
Bill.?
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Would like 4 encoder boards. Let me know cost and will pay through pay pal.
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Tom?
AB9EK
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Re: T41 V66.4 with Code Revisions
It is hardware issue.?
I am testing 3rd party BPF?
BCD input code is same as yours.
Tracing for short now.
Tim
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I have asked for some help and to purchase some boards through this site. I have not seen my posts or have a reply to them. Am I being black balled? If that's the case would someone please let me know.
?
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Tom AB9EK
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Re: boards and kits and stuff
I am interested in getting a 3.3 V board to see if it will further improve the receive noise on 6M by reducing radiation from the cable between the Main and Display boards. I have an AI6YM chassis with V12 Main, RF, and Front Panel boards. I use a 5" display in a shielded enclosure which greatly improved the RX noise floor on 80M through 10M (see the attachment).
John W2TX
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Re: T41 V12 Boards and K9HZ Kits in stock
Bill,
? ? ? ? ?Would like to order 4-encoder boards and 2- Teensy Offset boards and 20A Power Distribution kit. How do you take payments and shipping cost to zip code 53132.
?
?
? Tom AB9EK
?
E-mail; call @arrl.net
?
?
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I've sent a message several times asking about the digital post processor that was in the book "microcontroller s for amateur radio" and have gotten no response so no need for me to belong to the group....
Steve?
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Radiated EMI from displays
Hello, I discovered this project last Fall and this reflector even more recently. I have been reading the discussions about "Display Noise' and"SPI issues"? with much interest and since my experience is a bit different I will share it here.
I have built a V12 radio with RF, Main, and Front panel boards in an AI6YM chassis, using STDVer050.2 software.
I originally built the radio with a TFTM070A3-5 v4.0 (7") display and immediately noticed significant amounts of noise not normally heard from a radio with the antenna disconnected. This noise was below the level of the noise coming from my antenna on bands up through 15M, but above that the radio's internal noise was higher than antenna noise.
I made a simple probe from a piece of coax by removing 1 " of the shield from the end, connected the other end to my spectrum analyzer, and probed around the inside of my T41. I discovered what I believe to be a smps in the upper right corner of the rear of the display running at about 1.15 MHz. This smps exists in both the 5" and 7" displays. The 6th harmonic of this can be heard at the bottom of 40M and the 12th harmonic at the bottom of 20M; neither can be heard with my antenna connected but are very noticeable with the antenna disconnected.
I discovered very high levels of EMI radiated from the middle area of the circuit card on the back of the display. The spectrum of this EMI starts in the HF band, peaks around 160 MHz and has very significant strength in the 6M and 2M bands. I then noted that the layout of the boards in my chassis places the receive input circuitry about 2" from both the smps and the display EMI source. Not good!
I then clamped my coax to the chassis such that the 1" "probe" was right next to the receive RF input circuitry. I then made a simple shield/cover for the 7" display. In doing so, I discovered a few issues with the displays. First, the pads around the four mounting holes are not connected to the circuit ground, nor are they even connected to each other. On the 7" display, the four oblong, exposed, pads across the top are connected to the circuit ground, but the four across the bottom of the board are not, nor are they connected to each other.? When I then measured the noise from the probe with and without the shield in place on the 7" display there was some improvement, most noticeably on the smps noise, but the noise on the upper HF bands was still higher than the noise from the antenna.
I then looked at the 5" display. All four of its exposed, oblong, pads are connected to ground. I soldered small clips (from a Harmon EMI kit) to each of those four pads and made a shield to fit in those clips (see attached picture). I had to run a short wire from each clip to the closest mounting post to tie the shield to the chassis. This provided a very significant reduction in the level of noise present at the receive input circuitry.
To quantify the improvement, I measured the radio's sensitivity on each band and converted that to a receive noise figure. That can be compared to the level of noise that I measure from my antenna. This data is shown and graphed in the attached Excel file. The T41 receiver is very quiet now up through 10M. 6M is much improved, but further improvement is desired. Perhaps the cable..., perhaps moving the RF board away....
73,
John W2TX
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Re: Oscillations on high bands
I'm running 66.4 that I believe you sent me.? RX_SEL_BPF does not change state when PTT is pressed,? You can observe that on J1 of the LPF-Cntl pin 8.? You can see Pin 7 & 8 easily at that connector.? I plug a cable into J1 and then I can use a DVM or scope to easily access the pins.
I definitely have a problem with my setup.? So, my report on isolation will change.
dave
Thanks Dave! Do you mean that RX_BPF_SEL does not change state?
Can you point me to the source of the 66.4 code you're running? I want to try to figure out why this is the case.
On Tuesday, March 25th, 2025 at 9:48 AM, D Solt via <davesolt= [email protected]> wrote:
In ver 50.0 in SSB and CW modes, TX_BPF_SEL
and TR_BPF_SEL both switch states when PTT or Key engaged In ver 66.4 in CW mode, TX_BPF_SEL
and TR_BPF_SEL both switch states when Key engaged. In SSB mode, only
TX_BPF_SEL
switches state.
I am going to sweep the RX and TX paths to try to find blown
MASWSS0179's
dave, n3ds
By comparing your final plot (Isolation PA Out to PA In, LPF Cntl SN1, 25 MHz SSB, ver 50.0) to the plot of the same configuration with oscillating software loaded (Isolation PA Out to PA In, LPF Cntl SN1, 25 MHz SSB, ver 66.4), we see that the isolation is different between these two versions even though they have nominally identical configurations. Are you able to probe the control signals on the LPF board to see how they might differ?
I did notice that the Ver 66.4 CW isolation (which does not oscillate, IIRC) is identical to the Ver 50.0 SSB isolation (which also does not oscillate). So that is the configuration we should be seeking to replicate.
Regardless, the isolation is a lot worse than it should be, regardless of the configuration. Something is not right. We should expect about 48 dB of isolation from the MASWSS0179 switch alone:
This makes it seem like the TR switch is not working -- we should measure the TR switch performance on its own outside of the control board circuit.
On Monday, March 24th, 2025 at 3:55 PM, D Solt via <davesolt= [email protected]> wrote:
I ran some isolation tests today. Below is the first page of my report (attached).
I have had an oscillation at ~35MHz in the K9HZ 20-watt
power amp in my T41 V12 (SW ver 66.4) when I press PTT in the higher
bands. It appears to be caused by low
isolation between the PA Output, J8 and PA Input, J7, on the LPF-Control
board. Below are several plots from my
NanoVNA showing the isolation between 21MHz and 25MHz. On my two systems, the feedback oscillations
only occur above 22MHz.
The first plot shows the isolation with C18 removed from the
PCB. This capacitor is the path between
the transmit and receive RF switching circuits on the LPF-Control board. So is C7, but I didn¡¯t bother removing that. Isolation is better than 65dB with C18
removed.
The next two plots show the isolation at 25MHz in the CW
mode (key down) and SSB mode (PTT) engaged.
Isolation is in the 35dB range.
Additionally, the poor return loss in the SSB mode indicates that the
LPF is not being connected properly.
The next plot shows isolation at 50MHz in SSB mode with PTT
engaged. This is so bad (<25dB) that
I must have a bad RF switch.
The final two plots are done with version 50.0 at 21 and
25MHz. Performance in CW and SSB is
identical.
Conclusions:
¡¤
I may have a hardware problem or a test
equipment problem. Could someone else
duplicate this test?
¡¤
There is a software change in how CW and SSB are
controlled between version 50.0 and 66.4, but that bug doesn¡¯t seem to affect
isolation.
I found that the 25 MHz and 30 MHz bands oscillate, but the lower bands don't, matching what others have found.
To figure out why I measured the insertion loss from the output of the PA to the input of the PA. i.e., I connect port 0 of my NanoVNA to J8, and port 1 to J7. What this measures is the magnitude of the feedback loop.
What I found is that this is a lot higher than it should be, particularly at the higher bands.
| 7 MHz | 14 MHz | 21 MHz | 24 MHz | 28 MHz |
|-------|--------|--------|--------|--------|
|<-80dB | -63 dB | -53 dB | -48 dB | -47 dB |
I would expect roughly 40dB of insertion loss each through the T/R switch and the BPF selection switch U8. Clearly, I'm not getting that. It seems that the feedback amplitude is getting high enough at the higher bands to cause oscillations. What I would like to do next is:
1) Repeat this measurement for a known-good version of the code as identified by Jerry. Is this feedback path amplitude different?
2) Find the reason for the change in the feedback amplitude path by examining the LPF control signals between known-good and known-bad code.
Unfortunately, I am tied up for the week and won't be able to do this until next weekend.
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Re: Oscillations on high bands
Thanks Dave! Do you mean that RX_BPF_SEL does not change state?
Can you point me to the source of the 66.4 code you're running? I want to try to figure out why this is the case.
On Tuesday, March 25th, 2025 at 9:48 AM, D Solt via groups.io <davesolt@...> wrote:
In ver 50.0 in SSB and CW modes, TX_BPF_SEL
and TR_BPF_SEL both switch states when PTT or Key engaged In ver 66.4 in CW mode, TX_BPF_SEL
and TR_BPF_SEL both switch states when Key engaged. In SSB mode, only
TX_BPF_SEL
switches state.
I am going to sweep the RX and TX paths to try to find blown
MASWSS0179's
dave, n3ds
By comparing your final plot (Isolation PA Out to PA In, LPF Cntl SN1, 25 MHz SSB, ver 50.0) to the plot of the same configuration with oscillating software loaded (Isolation PA Out to PA In, LPF Cntl SN1, 25 MHz SSB, ver 66.4), we see that the isolation is different between these two versions even though they have nominally identical configurations. Are you able to probe the control signals on the LPF board to see how they might differ?
I did notice that the Ver 66.4 CW isolation (which does not oscillate, IIRC) is identical to the Ver 50.0 SSB isolation (which also does not oscillate). So that is the configuration we should be seeking to replicate.
Regardless, the isolation is a lot worse than it should be, regardless of the configuration. Something is not right. We should expect about 48 dB of isolation from the MASWSS0179 switch alone:
This makes it seem like the TR switch is not working -- we should measure the TR switch performance on its own outside of the control board circuit.
On Monday, March 24th, 2025 at 3:55 PM, D Solt via <davesolt= [email protected]> wrote:
I ran some isolation tests today. Below is the first page of my report (attached).
I have had an oscillation at ~35MHz in the K9HZ 20-watt
power amp in my T41 V12 (SW ver 66.4) when I press PTT in the higher
bands. It appears to be caused by low
isolation between the PA Output, J8 and PA Input, J7, on the LPF-Control
board. Below are several plots from my
NanoVNA showing the isolation between 21MHz and 25MHz. On my two systems, the feedback oscillations
only occur above 22MHz.
The first plot shows the isolation with C18 removed from the
PCB. This capacitor is the path between
the transmit and receive RF switching circuits on the LPF-Control board. So is C7, but I didn¡¯t bother removing that. Isolation is better than 65dB with C18
removed.
The next two plots show the isolation at 25MHz in the CW
mode (key down) and SSB mode (PTT) engaged.
Isolation is in the 35dB range.
Additionally, the poor return loss in the SSB mode indicates that the
LPF is not being connected properly.
The next plot shows isolation at 50MHz in SSB mode with PTT
engaged. This is so bad (<25dB) that
I must have a bad RF switch.
The final two plots are done with version 50.0 at 21 and
25MHz. Performance in CW and SSB is
identical.
Conclusions:
¡¤
I may have a hardware problem or a test
equipment problem. Could someone else
duplicate this test?
¡¤
There is a software change in how CW and SSB are
controlled between version 50.0 and 66.4, but that bug doesn¡¯t seem to affect
isolation.
I found that the 25 MHz and 30 MHz bands oscillate, but the lower bands don't, matching what others have found.
To figure out why I measured the insertion loss from the output of the PA to the input of the PA. i.e., I connect port 0 of my NanoVNA to J8, and port 1 to J7. What this measures is the magnitude of the feedback loop.
What I found is that this is a lot higher than it should be, particularly at the higher bands.
| 7 MHz | 14 MHz | 21 MHz | 24 MHz | 28 MHz |
|-------|--------|--------|--------|--------|
|<-80dB | -63 dB | -53 dB | -48 dB | -47 dB |
I would expect roughly 40dB of insertion loss each through the T/R switch and the BPF selection switch U8. Clearly, I'm not getting that. It seems that the feedback amplitude is getting high enough at the higher bands to cause oscillations. What I would like to do next is:
1) Repeat this measurement for a known-good version of the code as identified by Jerry. Is this feedback path amplitude different?
2) Find the reason for the change in the feedback amplitude path by examining the LPF control signals between known-good and known-bad code.
Unfortunately, I am tied up for the week and won't be able to do this until next weekend.
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That is strange. This sounds like the kind of error that can happen when the data structures stored on the EEPROM change, for instance when you move between versions of the code without erasing the EEPROM. But, by your description, you didn't do that.
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Bill, I don't have any oscillations, but then I don't have a LPF
or PA built yet. I lost over a week trying to get back to where I
could compile a running version.?
I attached the spectrum of the 10m & 6m outputs from the RF
board. The output on 6m is down significantly.
On 3/24/2025 12:08 AM, K9HZ via
groups.io wrote:
Any
oscillations on 10M or 6M?
?
?
Dr.
William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ
VP5/K9HZ PJ2/K9HZ VP2EHZ
?
Owner -
Operator
Big
Signal Ranch ¨C K9ZC
Staunton,
Illinois
?
Owner ¨C
Operator
Villa Grand
Piton ¨C J68HZ
Soufriere,
St. Lucia W.I.
Rent it:
?
Moderator:
North American QRO Group at Groups.IO.
Moderator:
Amateur Radio Builders Group at Groups.IO.
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email:? bill@...
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After totally scrubbing and rebuilding the IDE and libraries,
I can compile and run everything again. However Ver66.4 and
66.9 only run at 600MHz if TCXO is defined. They both freeze
if compiled with 528MHz.
The Receive I&Q Cal worked quite well, except the button
assignments don't agree with the directions.
Compiled with: Faster with LTO, 600 MHz, Dual Serial
SDTVer66.4
Memory Usage on Teensy 4.1:
? FLASH: code:308228, data:132408, headers:8892?? free for
files:7676936
?? RAM1: variables:194528, code:284488, padding:10424?? free
for local variables:34848
?? RAM2: variables:483744? free for malloc/new:40544
SDTVer66.9
Memory Usage on Teensy 4.1:
? FLASH: code:312196, data:132408, headers:9020?? free for
files:7672840
?? RAM1: variables:194784, code:288584, padding:6328?? free
for local variables:34592
?? RAM2: variables:483744? free for malloc/new:40544
--
73 
Bob W3RDL
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73
Bob W3RDL
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jjpurdum
