Jerry,
Correct, we need the pullup on A0 for reasons of backward compatibility.
At startup the firmware detects whether or not the PTTsense line is
installed. When the PTTsense is NOT installed, input A0 will be open.
Without a pullup the digital level will be undefined so we won't be able
to reliably detect this condition.
With the pullup resistor enabled, and a 10K resistor in the PTTsense line,
we typically get 1.25V on A0 during RX, which is well below the threshold.
You could use a smaller resistor value but it shouldn't be necessary.
BTW, the 1.25V suggests that the internal pullup resistors are about 30K,
which is smaller than I expected (I've always thought they were at least
50K).
73 Allard PE1NWL
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On Sun, October 1, 2017 20:01, Jerry Gaffke via Groups.Io wrote: Allard,
You are writing your firmware in such a way that users need not apply all
mods.
That might require a pullup or pulldown on A0, in which case it's best to
ignore my previous post.
If thresholds at A0 become an issue, perhaps the recommended resistor at
A0 could be reduced from 10k,
Perhaps as low as 1k?
Measurements are probably the best source of information here.
However, from the datasheet:
Figures 33.25 and 33.26 on pages 391 and 392 of ??
??
(
)
show the input threshold with Vcc at 5v to be somewhere between 2.1 and
2.7 volts for a digital input on the ATmega328p
Figure 33.17 on page 387 shows pullup current from a pin at 1.3v to be
around 100uA, so (5-1.3)/0.1mA = 37k
for the typical effective pullup resistance for an ATmega328p digital
input with Vcc at 5v.
Jerry
On Sun, Oct 1, 2017 at 10:39 am, Jerry Gaffke wrote:
Allard,
What you have works well enough.
But on the next rev of firmware, you might remove the pullup from A0.
(As you are likely already planning to do.)
|
Re: W8TEE pending software release and port(?)
#w8tee
Hi Jack,
I'm still waiting for my BitX kit (I fear it may have gone missing) but I have all the parts for the VFO and will start construction using the new manual. I would like to vote for split mode (I think this is already implemented in Raduino with PTT sense mod?) and CAT for digi modes using WSJT-X, etc.?
Thanks,
Paul
KG6QGE
|
Not sure if anyone else has noticed anything similar, but here is an interesting observation.
I have a cheap mfj travel paddle I was using to test the qsk and keyer functions. I'm using an end fed half wave, fed through a 4:1 balun, about 30ft of coax? tuner in the shack. Not ideal for qrp. I noticed that often when using the keyer, the speed reduces by one step each time I hit the key, going from 20 wpm, down to one. Interestingly, if I use my good paddle, the problem does not seem to occur. I have already checked that d3 and d4 are not shorted, as this could cause the problem...but if so, it would occur all the time, with the good key as well. Anyone else see anything like this?
Also, regarding My earlier comments regarding using an audio tone to generate cw...on my rig anyway,when tuning a strong signal, you do hear a fairly noticeable tone on the wrong side of zero beat, so I guess the filter would not be good enough to avoid an upper sidebar cw signal.
|
Re: dc power connection bitx40 confusion
While reading this thread, I am sure that many builders have wired their BITX-40's for dual voltages.? If you have, I would like to see a posting here on just how you accomplished it.? This would save me a little work on trying to figure it out, hi hi.? I am thinking of dual position switch, (I would mount it on the rear of the chassis) that would have the entire radio to operate on 12vdc, with the second position, putting 24vdc on PA only.? Please, your schematic here.? 73, de KO8S, Karl
On Sunday, October 1, 2017 3:23 PM, Keith VE7GDH <ve7gdh@...> wrote:
Paul (call sign?) wrote...
> confused on the e DC power connection instructions...
that Jerry pointed out pretty much says it all.
Keep in mind that there are two places on the main
circuit board that need to get power. The Raduino
also needs power. The power connection at the back
right of the main board (if you have the PA at the
back) is power to everything else on the main board.
The power connection over near the IRF510 PA is for
the final and nothing else. This is so you can
optionally run the PA at a higher voltage... with a
larger heat sink. If you are going to run everything
on 12V, just connect the three places together
wherever you switch the power on and off and of
course tie all of the grounds together too, avoiding
ground loops.
--
73 Keith VE7GDH
|
Ah, that explains it all. Glad you found it, thanks for letting us know.
And now... happy BitX-ing!
73 Allard PE1NWL
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On Sun, October 1, 2017 21:34, kg4usk@... wrote: **SOLVED**
Yep, it sure was a short between A0 and A1. A bit of sloppy soldering on
the Arduino MCU. I could have sworn I checked earlier, but must have
overlooked this tiny spot.
Thanks again for all the help! And sorry for the "duh" moment mistake!
|
**SOLVED** Yep, it sure was a short between A0 and A1. A bit of sloppy soldering on the Arduino MCU. I could have sworn I checked earlier, but must have overlooked this tiny spot. Thanks again for all the help! And sorry for the "duh" moment mistake! 
|
Re: dc power connection bitx40 confusion
Paul (call sign?) wrote... confused on the e DC power connection instructions... The post at /g/BITX20/message/23973that Jerry pointed out pretty much says it all. Keep in mind that there are two places on the main circuit board that need to get power. The Raduino also needs power. The power connection at the back right of the main board (if you have the PA at the back) is power to everything else on the main board. The power connection over near the IRF510 PA is for the final and nothing else. This is so you can optionally run the PA at a higher voltage... with a larger heat sink. If you are going to run everything on 12V, just connect the three places together wherever you switch the power on and off and of course tie all of the grounds together too, avoiding ground loops. -- 73 Keith VE7GDH
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audio preamp might be busted. the LM386 seems to be working (from the test that you performed). check the voltages around the audio preamp's base and collector.? if the LM386 gives you noise, does the volume control give you noise too? trace the connectivity from pin 3 of the LM386 to the volume control's middle lug. if the noise ensues when you touch a wire to the middle lug of the volume control, then move to the upper lug (not the one connected to the ground), if that works, then, check at the collector of the audio preamp. essentially, you hve to get to the point beyond with the audio doesn't pick up and you have located the trouble.
- f
On Mon, Oct 2, 2017 at 12:23 AM, Ken Macy <kmacy@...> wrote: When I first set up the Bitx40, it did seem to receive OK.? Then there began to be various, random ¡°drop outs¡± into silence.? Cycling the power usually got it back.? Then one day it went dead and never came back.? There was noise from the speaker when touching pin3 of the LM386, or where pin3 is connected to the volume pot.? Now it doesn¡¯t even do that.? The only output is when LM386 pin3 is fed a 0 dB 1KHz audio tone; the audio amp seems to work.?
?
The Raduino, DDS and display seem to be working, also the transmitter works!?
?
While sitting there being quiet, it draws 170ma, which seems high.?
?
I¡¯ve reviewed Farhan¡¯s troubleshooting video and I get no noise whatever at any of the points in the circuit he points out.? Measuring voltage at the points shown in the table by K7AGE all match what he lists there.
?
I¡¯ve read pages and pages of postings here and I haven¡¯t read anything close to this.? Any help on where to look next is welcome.
Ken, KG6PO
|
Re: BITX QSO Night, Sunday, October 1, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere
Bump to top!
--
John - WA2FZW
|
When I first set up the Bitx40, it did seem to receive OK. ?Then there began to be various, random ¡°drop outs¡± into silence.? Cycling the power usually got it back.? Then one day it went dead and never came back.? There was noise from the speaker when touching pin3 of the LM386, or where pin3 is connected to the volume pot.? Now it doesn¡¯t even do that.? The only output is when LM386 pin3 is fed a 0 dB 1KHz audio tone; the audio amp seems to work.?
?
The Raduino, DDS and display seem to be working, also the transmitter works!?
?
While sitting there being quiet, it draws 170ma, which seems high.?
?
I¡¯ve reviewed Farhan¡¯s troubleshooting video and I get no noise whatever at any of the points in the circuit he points out.? Measuring voltage at the points shown in the table by K7AGE all match what he lists there.
?
I¡¯ve read pages and pages of postings here and I haven¡¯t read anything close to this.? Any help on where to look next is welcome.
Ken, KG6PO
|
From what I can tell, everything checks out OK.
Voltage on A0 attached through 10k resistor to regulator output is ~1.22v RX, 5v TX. Regulator pin 1 is 0v RX, 5v TX. Regulator pin 3 is 0v RX, 12v TX.
It appears that the Raduino at least knows when the PTT is pressed. After it powers up in "CWL" mode, pressing the PTT for about 250ms switches it to "LSB". Pressing PTT again for approx 250ms causes "TX" to flash once quickly.?
|
Re: W8TEE pending software release and port(?)
#w8tee
Check my photo album at the site, then.
Jack, W8TEE
From: "dm5tu@..." <dm5tu@...>
To: [email protected]
Sent: Sunday, October 1, 2017 1:59 PM
Subject: Re: [BITX20] W8TEE pending software release and port(?) #w8tee
Hi Jack,
sorry but my feedback is the same... no ?inline picture on the side. I am even logged in.
TNT fer all . sTef DM5TU es 72/3`s
|
Allard,
You are writing your firmware in such a way that users need not apply all mods.
That might require a pullup or pulldown on A0, in which case it's best to ignore my previous post.
If thresholds at A0 become an issue, perhaps the recommended resistor at A0 could be reduced from 10k,
Perhaps as low as 1k?
Measurements are probably the best source of information here.
However, from the datasheet:
Figures 33.25 and 33.26 on pages 391 and 392 of ?
?
show the input threshold with Vcc at 5v to be somewhere between 2.1 and 2.7 volts for a digital input on the ATmega328p
Figure 33.17 on page 387 shows pullup current from a pin at 1.3v to be around 100uA, so (5-1.3)/0.1mA = 37k
for the typical effective pullup resistance for an ATmega328p digital input with Vcc at 5v.
Jerry
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Show quoted text
On Sun, Oct 1, 2017 at 10:39 am, Jerry Gaffke wrote:
Allard,
What you have works well enough.
But on the next rev of firmware, you might remove the pullup from A0.
(As you are likely already planning to do.)
|
Re: W8TEE pending software release and port(?)
#w8tee
Hi Jack,
sorry but my feedback is the same... no ?inline picture on the side. I am even logged in.
TNT fer all . sTef DM5TU es 72/3`s
|
Allard,
What you have works well enough.
But on the next rev of firmware, you might remove the pullup from A0.
(As you are likely already planning to do.)
toggle quoted message
Show quoted text
On Sun, Oct 1, 2017 at 10:28 am, Allard PE1NWL wrote:
A0 should be approx 1.25V (LOW) during RX,
|
A0 should be approx 1.25V (LOW) during RX, 5V (HIGH) during TX.
If this is not the case, first make sure that U3 is switching on and off
correctly during RX/TX. U3 input pin 3 should be 12V during TX, zero
during RX. U3 output pin 1 should be 5V during TX, zero during RX.
Please confirm and let me know before going to the next trouble-shooting
steps.
73 Allard PE1NWL
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On Sun, October 1, 2017 16:32, kg4usk@... wrote: A0 and A1 both show 5v, PTT on and off. I don't have a key connected at
the moment.
I understand A1 is pulled low to send a carrier, but shouldn't A0 always
be low until it sees 5v from the regulator?
|
Yup, output of the 78L05 regulator should be zero volts when receiving, 5v when transmitting.
It is powered from the TX rail of 12v, which is zero volts when receiving and 12v when transmitting
Check that the input pin ?(pin 3) of the 78L05 at U3 is 0 volts when receiving, and that the output is also 0 volts when receiving.
If that's the case, then you likely didn't wire up Allard's 10k resistor correctly from 78L05 output to A0.
Or possibly, A0 is shorted to some other source of 5v.
A0 may have a pullup internal to the ATmega328P processor, but that is over 50k ohms and the 10k resistor?
should bring A0 down under a volt during receive.?
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On Sun, Oct 1, 2017 at 07:32 am, <kg4usk@...> wrote:
A0 and A1 both show 5v, PTT on and off. I don't have a key connected at the moment.
I understand A1 is pulled low to send a carrier, but shouldn't A0 always be low until it sees 5v from the regulator?
|
A0 and A1 both show 5v, PTT on and off. I don't have a key connected at the moment.
I understand A1 is pulled low to send a carrier, but shouldn't A0 always be low until it sees 5v from the regulator?
|
What are the voltages on A0 and A1 if you measure them with a DVM?
What voltages do you have when you press PPT or the CW key?
73 Allard PE1NWL
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On Sun, October 1, 2017 14:55, kg4usk@... wrote: Thanks for getting back to me Allard.
No shorts anywhere. I've done the reset and it does the same thing. There
is nothing connected to the A1(KEY) wire. Do the CW Carrier and TX-RX
connections need to be hooked up simultaneously in order for this to work?
|
Thanks for getting back to me Allard.
No shorts anywhere. I've done the reset and it does the same thing. There is nothing connected to the A1(KEY) wire. Do the CW Carrier and TX-RX connections need to be hooked up simultaneously in order for this to work?
|
Allard PE1NWL
Brent Seres/ VE3CUS
sTef - DM5TU / VY1QRP