D2 and D3 are illuminated? ? If so the power rails are working. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Mar 30, 2025, at 12:47?PM, Tom Schulte via groups.io <tomschulte9@...> wrote:
? Thanks for the advice. Here's what I have done so far.
?
1. Replaced the LM117
2. J5- 3v and 5V on their pins
3. 5v on TP1
4. 3.3v on TP2
5. 12v on Fan port
6. Replace the pin connector for the teensy
7. No voltage? on? pin 46?
8.? 5v on pin 48
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Will keep on looking for the problem.
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Tom
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Thanks for the advice. Here's what I have done so far.
?
1. Replaced the LM117
2. J5- 3v and 5V on their pins
3. 5v on TP1
4. 3.3v on TP2
5. 12v on Fan port
6. Replace the pin connector for the teensy
7. No voltage? on? pin 46?
8.? 5v on pin 48
?
Will keep on looking for the problem.
?
Tom
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1) I would take out the teensy (socketed? and possible?) and would check the TP?s like Oliver
2) if it?s ok 4 possibilities
a) Teensy is defekt
b) check Teensy Pin 46 (without Teensy) is there a short? Teensy is only able to deliver 250mA on this pin.
c) a solder bride? look for Connector J5 (disconnect cable, once I had a short)
d) one of the 3.3V consumer has a short. Please disconnect all cables (display, matrix, etc.....)
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check the poor mainboard and connect without teensy the cables 1by1 and check the voltages! special on 3.3V rail!
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I hope you are successful
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Re: Oscillations on high bands
Here's the gain of my K9HZ 20W PA:
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If we calculate the gap between the feedback amplitude and the amplifier gain, we can quantify how much margin we have before the radio begins to oscillate. It's a noisy measurement because of my NanoVNA's noise floor, but we have at least 17dB of margin.
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If I upgrade my radio to include a 100W amplifier (7dB increase in gain), this reduces the margin to at least 10dB.
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I had a Teensy blow when on power up because a the LM1117 failed. I replace the LM1117 with MP2307 buck converter module. The LM1117 had the fan and heatsink on it but its current rating is inadequate.
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Re: Oscillations on high bands
Good detective work. ? That should do it. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Mar 30, 2025, at 6:53?AM, Oliver KI3P via groups.io <oliver@...> wrote:
? I discovered that U8 (an RF switch) was not working on my LPF board. It provided very little isolation. I measured this by removing the LPF control board from my radio and testing it a NanoVNA and the LPF board testing sketch. I removed the TR carrier board, connected the transmit and receive lines together with a short piece of wire, and measured the transmission between J23 (the output of the LPF) and J18 (one of the BPF inputs) as shown in this diagram:
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Here is the measured transmission between these points before and after I replaced U8:
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After I replaced U8 I got very low feedback between the output and the input of the 20W amplifier, as shown below. I will reassemble my board now and confirm that this remains the same when running the latest software.
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Re: Oscillations on high bands
I have now confirmed that, after I replaced U8, the latest version of the code (Ver66-9) on does not suffer from oscillations on any band with my V12 radio.
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Also don't forget you have to slice the trace on the Teensy to disconnect the USB power.
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--
73 Greg KF5N
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Do you know how your Teensy got blown? That shouldn't happen.
Before placing your Teensy on the board, power it up and check that the DC voltages are correct. The schematic is here:
Check the following: - TP1 is +5V
- TP2 is +3.3V
- Pin 48 of the Teensy is +5V
- Pin 1 of J2 (Fan connector) is +12V
How much current does your board draw without the Teensy or fan in place? It should be pretty low -- maybe a few 10's of mA for U5 and U6.
On Saturday, March 29th, 2025 at 4:56 PM, Tom Schulte via groups.io <tomschulte9@...> wrote:
? I have a major problem with the main board. I built it with the reverse power protection. When I first built it I had 3.3vand5v at the test points. Now when I added the teensy and audio hat and test it I get I2C devices not found.? Also I have 1.35 amps and 14 watts per? the power supply meters. No longer have 3.3 v and the LM117 is very very hot to the touch. I? blow one teensy replaced with new one and resoldered all pins still no luck. Can someone point me in the right direction? to look for? the problem?
?
?
Tom AB9EK
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Re: Oscillations on high bands
I discovered that U8 (an RF switch) was not working on my LPF board. It provided very little isolation. I measured this by removing the LPF control board from my radio and testing it a NanoVNA and the LPF board testing sketch. I removed the TR carrier board, connected the transmit and receive lines together with a short piece of wire, and measured the transmission between J23 (the output of the LPF) and J18 (one of the BPF inputs) as shown in this diagram:
?
?
?
Here is the measured transmission between these points before and after I replaced U8:
?
?
After I replaced U8 I got very low feedback between the output and the input of the 20W amplifier, as shown below. I will reassemble my board now and confirm that this remains the same when running the latest software.
?
?
?
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Re: boards and kits and stuff
Great Terrance, thanks for the post. ?I hope others results will be good too. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Mar 29, 2025, at 8:03?PM, Terrance Robertson, KN6ZDE via groups.io <tmrob4@...> wrote:
? I can report success with Bill's display driver board and also a caution.? I accidentally connected the display driver board to the Main board offset by one row and blew the MISO line.? Bodging that signal across the board, I was able to run the T41 display with a three-foot cable.? I couldn't run the display with a six-foot cable.? I don't think that was due to my unaugmented MISO signal.? The board will drive the display on a shorter cable without the MISO signal at all, though at a sluggish rate.
?
? <IMG_20250329_162332274.jpg>
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Re: boards and kits and stuff
I can report success with Bill's display driver board and also a caution.? I accidentally connected the display driver board to the Main board offset by one row and blew the MISO line.? Bodging that signal across the board, I was able to run the T41 display with a three-foot cable.? I couldn't run the display with a six-foot cable.? I don't think that was due to my unaugmented MISO signal.? The board will drive the display on a shorter cable without the MISO signal at all, though at a sluggish rate.
?
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? I have a major problem with the main board. I built it with the reverse power protection. When I first built it I had 3.3vand5v at the test points. Now when I added the teensy and audio hat and test it I get I2C devices not found.? Also I have 1.35 amps and 14 watts per? the power supply meters. No longer have 3.3 v and the LM117 is very very hot to the touch. I? blow one teensy replaced with new one and resoldered all pins still no luck. Can someone point me in the right direction? to look for? the problem?
?
?
Tom AB9EK
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Re: Oscillations on high bands
Interesting, Jerry. If you have time, could you measure isolation from J8 to J7 with key down in CW, and PTT engaged in SSB, with your current SW version?
dave
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Schematic and BOM on the GITHUB
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Mar 28, 2025, at 4:36?PM, Steve Umans via groups.io <umans@...> wrote:
? I completed my RF board last fall based upon the BOM "T41_RF_Board_BOM_V012.6_02-25-24.xlsx".? My RF board seems
to work OK although "how well" is still a question.? I have not followed properly the various messages about possible/suggested
changes to the RF board and I am wondering if there is a single location where one can find a complete summary of
the "latest and greatest" upgrades/modifications since the February 25, 2024 bill of materials was issued.
?
Thanks,
Steve
K8ZBE
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I completed my RF board last fall based upon the BOM "T41_RF_Board_BOM_V012.6_02-25-24.xlsx".? My RF board seems
to work OK although "how well" is still a question.? I have not followed properly the various messages about possible/suggested
changes to the RF board and I am wondering if there is a single location where one can find a complete summary of
the "latest and greatest" upgrades/modifications since the February 25, 2024 bill of materials was issued.
?
Thanks,
Steve
K8ZBE
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Re: Oscillations on high bands
Today, I checked v50.2 and v66.4 after putting my T41's back together. ? Both versions have a 33-45MHz oscillation at the higher bands.? I have pretty low isolation PA Out to PA In at those frequencies on the 12-6 meter bands.? I am thinking that I must have a hardware issue since I am not getting the isolation numbers that Oliver posted.? I'm going to set this aside for a while.
dave, n3ds
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Re: boards and kits and stuff
This should have arrived sometime today¡
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
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On Mar 20, 2025, at 5:33?AM, Albert Peter via groups.io <albertfpeter@...> wrote:
? Bill,
My system is working and without freeze-ups, but I will try out your board.
Al
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Re: Radiated EMI from displays
Another way to test this is to disconnect the display altogether.? This can't be done with the existing software as the code will hang trying to start the RA8875 object.? However, in developing the T41 Beacon Monitor, I created a version of the T41 software that doesn't update the display, though the RA8875 object was still there to display the Beacon Monitor.? With a bit of work, I separated that portion of the display code as well.? I can now completely disconnect the display.? It's not too hard to print the S-meter value to the serial monitor, but controlling the radio without a display is a bit of a guess.? That's where my comes in handy.?
With that I see a 10 to 20 dB reduction in the noise floor on the upper bands of the 4SQRP without its 5" display.? This seems consistent with the results that John posted.
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I need to repeat this with my v12.
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K9HZ
JerryP