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I wonder if anyone can help me with this problem.? My recently completed bitx-40 will tune only from 7.075 to 7.109 and does not scroll up or down at the ends of the pot movement.? I have tried various versions of the software including the latest V 1.27.2 and it is the same with all of them.? The voltage at the slider of the pot varies between just over 0v to just under 5v.? I am stumped!? Any help would be greatly appreciated.
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On Sat, Nov 18, 2017 at 03:58 am, David Holland wrote:
The voltage at the slider of the pot varies between just over 0v to just under 5v
It is strange that the voltage doesn't reach 0V and 5V. Perhaps a poor quality potentiometer? If the slider voltage doesn't reach the upper and lower limits the software will never start scrolling up or down. 73 Allard PE1NWL
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I have changed the pot - no difference. I have disconnected the purple
green and yellow wires from the pot and measured the voltages very
accurately. They are Purple wire 1.855v, Green Wire 4.91v and yellow
wire 0v.
I am still stumped. Could the problem be in the actual Arduino?
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On Sat, Nov 18, 2017 at 05:41 am, David Holland wrote:
Green Wire 4.91v and yellow wire 0v.
These should be 5V and 0V exactly. What did you use as a reference (ground) point for these measurements? Check your wiring and ground connections and make sure that connectors are properly seated. The 5V (green wire) is coming directly from the voltage regulator output. What voltage do you measure directly at the 7805 regulator? The yellow wire (0V) is connected to ground. 73 Allard PE1NWL
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The voltage actually at the 7805 is 4.91v. This is using a Fluke 75
digital multimeter that I have checked against other known sources. I
have changed the 7805 and the voltage is still the same!!!!
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I would not worry about that 4.91v.
The 7805 is a 40 year old design, and even modern ones can be off by one or two percent.
Datasheet says to expect an output of anything between 4.75 and 5.25 volts.
That LM7805 on the Raduino is running kind of hot and with significant current,
both of which will bring the output voltage down a bit.
?
Jerry, KE7ER
On Sat, Nov 18, 2017 at 08:52 am, David Holland wrote:
The voltage actually at the 7805 is 4.91v.
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OK then, according to Jerry the voltage is not critical so I appear to
back to square one! Anybody got further ideas. All help would be
greatly appreciated.
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The LM7805 being off a bit should not matter here, since the Nano is likely using Vcc as the reference high voltage for the analog-to-digital converter.
Though it is very strange that the Nano is not seeing voltages low and high enough for the firmware to go into scrolling mode, as Allard says.
Exactly what are the lower and upper voltages you see from the pot's slider?
Set the pot to mid-range, short the slider ground, does the display jump down in frequency?
With the pot still at mid-range, short the slider to 5v, does the display jump up in frequency?
If that works, I suggest swapping out the pot.
Anything between 1k and 100k would probably work, original pot is 10k, should be linear taper not logarithmic.
If you were to set the pot to its maximum voltage ansd short the slider to ground, you are shorting the LM7805's 5v output to ground.
If you set the pot to its minimum voltage and short the slider to 5v, you are again shorting the LM7805 to ground.
Be careful not to do either.?
Probably should be a fixed resistor of maybe 1k on the Raduino board between 5v and the top of the pot,
as somebody mis-wiring a multi-turn pot (very easy to do!) can quickly burn up a $20+ investment in their fancy pot.
But the firmware would have to know that the top of the range from the pot is then not quite 5v.
Jerry, KE7ER
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On Sat, Nov 18, 2017 at 03:58 am, David Holland wrote:
The voltage at the slider of the pot varies between just over 0v to just under 5v.? I am stumped!
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OK, so you have 4.91V from the 7805 (let's assume this is still within specs), and this voltage also arrives (without drop) at the one end of the potentiometer.
At the other end you have zero volts.
What reference ground point did you use for these measurements?
What voltage do you measure on the slider when it's at either end of the pot?
Does the slider voltage vary over the full (0V - 4.91V) range when you turn the pot?
73 Allard PE1NWL
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Answers to questions and further info:-
OK, so you have 4.91V from the 7805 (let's assume this is still within specs), and this voltage also arrives (without drop) at the one end of the potentiometer.
At the other end you have zero volts.
What reference ground point did you use for these measurements? ? - The actual centre pin of the 780 regulator chip
What voltage do you measure on the slider when it's at either end of the pot? - 0v and 4.91v
Does the slider voltage vary over the full (0V - 4.91V) range when you turn the pot? - Yes
Also noted is that when the pot is at the 5v end the display shows both "Dial is locked" and "TX".
The plot thickens!!!
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This is all very strange.
I suspect there may be issues with the wiring (especially with the ground connections).
Or perhaps with the power supply (stability, noise).
Which mods did you install?
For trouble-shooting you could uninstall them and first make sure that the radio basically works without any mod (the software should still basically work without any mod).
Then reinstall them one by one and see when the problem returns.
73 Allard PE1NWL
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Does the purple wire vary from 0 to 5V when your turn the pot ?
If it does then it could be the nano.
Raj
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At 18/11/2017, you wrote: I have changed the pot - no difference. I have disconnected the purple
green and yellow wires from the pot and measured the voltages very
accurately. They are Purple wire 1.855v, Green Wire 4.91v and yellow
wire 0v.
I am still stumped. Could the problem be in the actual Arduino?
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Time for a meter recal ?
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At 18/11/2017, you wrote: The voltage actually at the 7805 is 4.91v. This is using a Fluke 75
digital multimeter that I have checked against other known sources. I
have changed the 7805 and the voltage is still the same!!!!
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Would be interesting to hack the script to display the analog reading from the tuning pot pin on the second line.
Might try adjusting the script to move the tuning pot to some other analog pin.
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On Sat, Nov 18, 2017 at 07:39 pm, Raj vu2zap wrote:
Does the purple wire vary from 0 to 5V when your turn the pot ?
If it does then it could be the nano.
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My version of code has a tuning indicator on the second line. I managed
to make 16 characters in to 80 columns
and display the pot position.
Dropbox link
Raj
At 19/11/2017, you wrote:
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Would be interesting to hack the
script to display the analog reading from the tuning pot pin on the
second line.
Might try adjusting the script to move the tuning pot to some other
analog pin.
On Sat, Nov 18, 2017 at 07:39 pm, Raj vu2zap wrote:
- Does the purple wire vary from 0 to 5V when your turn the pot
?
- If it does then it could be the nano.
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On Sat, Nov 18, 2017 at 07:59 pm, Jerry Gaffke wrote:
Would be interesting to hack the script to display the analog reading from the tuning pot pin
Try the sketch attached, which sends the analog reading from the tuning pot to the serial monitor for trouble-shooting purposes. (this is the only addition, for the rest it's identical to v1.27.2.) You need to keep your USB cable connected to your PC, and open the serial monitor from the IDE (tools => serial monitor). A window will pop up and the raduino will reboot. After a few seconds you will see the actual readings from the pot. The values should range from 0-1000 73 Allard PE1NWL
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I have uploaded the test sketch Allard and followed your instructions.
A window does indeed pop up. It is empty. Nothing further happens!
I should mention that last night I bit the bullet and with a great deal
of patience I changed the Arduino for a know good one from another
project. I guess that eliminates that. There is not a great deal
left! I am on the verge of abandoning the whole project as a dead loss!
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On Sun, November 19, 2017 12:50, David Holland wrote: I have uploaded the test sketch Allard and followed your instructions.
A window does indeed pop up. It is empty. Nothing further happens! I suspect there may be some hardware issue on the Raduino board. You should at least get something out on the serial monitor. I am on the verge of abandoning the whole project as a dead loss! That would certainly be a great pity. Why not order a new raduino and give it another try? Your BitX40 main board still seems to be OK. And with a good working Raduino it would make it a great radio. 73 Allard PE1NWL
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Seems the Raduino is mostly working.
Could be his main computer has some issue with getting that serial monitor to work.
Dumping readings to the LCD might be more reliable.
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On Sun, Nov 19, 2017 at 05:46 am, Allard PE1NWL wrote:
On Sun, November 19, 2017 12:50, David Holland wrote:
I have uploaded the test sketch Allard and followed your instructions.
A window does indeed pop up. It is empty. Nothing further happens!
I suspect there may be some hardware issue on the Raduino board.
You should at least get something out on the serial monitor.
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OK Allard.? New Raduino ordered.? Project set aside until arrival.? No
hair left to pull out!!!
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On 19/11/2017 13:46, Allard PE1NWL wrote: On Sun, November 19, 2017 12:50, David Holland wrote:
I have uploaded the test sketch Allard and followed your instructions.
A window does indeed pop up. It is empty. Nothing further happens! I suspect there may be some hardware issue on the Raduino board.
You should at least get something out on the serial monitor.
I am on the verge of abandoning the whole project as a dead loss! That would certainly be a great pity.
Why not order a new raduino and give it another try?
Your BitX40 main board still seems to be OK. And with a good working
Raduino it would make it a great radio.
73 Allard PE1NWL
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Allard PE1NWL
Raj vu2zap