Re: Mic doesn't work in bitx40 #bitx40

Tim Gorman

1.4v is the base bias for the transistor. It is developed through
resistors R61 and R62. If you have 12v at the TX point then the voltage
at the base of the transistor will be (R61/(R61+R62+R66) times the TX
voltage or 10v * {2.2K/(2.2K+10K+220) is approximately 1.7v. Your
voltage is a little low but close.

It sure sounds like you have your mic wired backwards. Swap the leads
to your electret mic and see if it helps.

tim ab0wr

On Thu, 17 May 2018 20:52:15 -0700
qonita.salimah@... wrote:

Thank you for your reply..
So the one that I bought is the electret condenser mic. 
When I didn't connect the mic to the circuit the voltage from 4.7KOhm
resistor is about 9.5-10Volt. But when I connect it to the mic, the
voltage suddenly drop to the 0.131-0.135Volt. 

And the 1uF polar capacitor, also behaving weird. The positive side
is show the same exactly voltage with the output from 4.7KOhm
resistor. But the negative side always show 1.4Volt, even when the
mic is connected or not.

Please help me. Thank you

Re: Raduino CAD Files


I had a look at the links and there doesn't seem to be any CAD files there. I guess I'll have to break out the caliper and measure the stock board.

Re: Raduino CAD Files


Thanks everyone for the help!

Jerry, yes, I've been busy behind the scenes doing a lot of things with the control system. I now have the entire app running on an STM32F103 "Blue Pill" board, which is only about $2.50 on Ebay. This gives me a 70 mHz 32 bit controller with 128K bytes of program memory. My software S-meter is now working quite well and only requires 2 resistors and a cap, plus some code. I'm using a separate ILI7735 display for the S-meter, both displays on the same SPI bus. The S-meter is derived from a 10kHz sample-rate of the pre-amp audio, with software peak detection. The TFT meter display has a max-hold pointer that resets every few seconds, while the main pointer is real-time. There are digital readouts on it for peak signal level in uV, dBm and S-units. The measurements from the S-meter will drive a digipot after the audio pre-amp to effect a feedforward AGC. Feedforward, with software calibration, should make for a very fast acting AGC without the overshoot/undershoot artifacts of feedback systems. I'm also using a 400 ppr optical encoder for frequency control with interrupt processing; it tunes beautifully smooth, with 1 hZ steps and software acceleration. . All of this puts a real strain on the little Nano u-controller, hence the move to the Blue Pill. I intend to layout a new Raduino that accepts the 'pill', with extra connectors for SPI and I2C busses. I developed my own tinier version of the Adafruit Si5351 board that will mount on the Raduino. I might even use a separate Si5351 for the main VFO in order to eliminate the crosstalk spurs generated in the single-chip approach. This was all moving smoothly while I was house-bound during Winter, but will slow down while the weather's nice outside.


Re: rough draft of how to connect BITX to PC for digital modes wiki


Thanks Doug, your notes are very helpful.

73, Dennis

Re: Raduino not working 0 Volts on Pin 6 (red wire) #ubitx-help #ubitx

Gary Anderson

These might not apply to Rogier's issue, but since I have already typed this up, it may be still helpful to him or someone else.

I had 2 issues when trying to connect to the supplied Nano on the Raduino board to my Windows 10 machine.
1. USB connection.   I started with a cheap working cable (that I use with Segger J-link debugger boards all the time) and did not get a power connection.
    Fiddled around on a Friday evening, I am aware that the USB connector on the Nano clone board may be an issue. (socket + connector tolerance)
    With the right pressure from the thumb, I could get intermittent connection.  OK, making progress.
    Went through the stash box and found a 'better' (well at least more expensive) USB cable with ferrite chokes on either end, that made solid connection.
2. Driver. (nothing found on PC comport)  Well there had been some discussion of issues with Macs (that wasn't forefront in my mind at this time) 
   With hesitation, I downloaded a CH341 driver for Windows.
   (installation complained about not being successful, but the driver was working)

Now I was up and running. Time for an adult  refreshment, sofa and bed.
Project gets side tracked for other things.  When I get back to playing with the Nano clone,  What do I do?  Use my everyday cable.
It doesn't work. Momentary lapse of sanity.  Get the 'better' cable and all is O.K.

This was the first time I played with a Nano clone.  My only experience with Arduino is the Uno R3.  I use them often for adding quick instrumentation, remote pin control of hardware under test, etc.
Clones are cheaper and make sense to use in various projects, like this one.  
However, If your budget allows, I'm an advocate of having at least 1 of the mainstream top tier manufactured products when you are self teaching.
Having additional obstacles to overcome when your intent is to 'learn Arduino' can be frustrating.  


Re: Low Power Output for Hendricks BitX20A - Watt meters and Scope readings do not agree.... #bitx20


The check would be you must be putting st least 2A into (24W to the finals, ~50% efficiency)
the finals to be in the 10-12W region.

I don't ever believe scope readings as accurate. For power out I use a dummy load with a
diode detector or a 30-40 db power attenuator as I have a calibrated unit 30db and 10db
that into the spectrum analyzer gives good reading for power.  If all else fails if my 10W
dummy gets hot its likely more than 10W.  The latter with a thermometer can be calibrated
for power equal temperature using a variable power supply (DC power=RMS power).

At some point you need an instrument you can believe.


Re: rough draft of how to connect BITX to PC for digital modes wiki

_Dave_ AD0B

I found that there was too much attenuation in the ezdigi board so I use just the isolation transmformers and bipassed the rest. Mounted the board into the ubitx case and hardwired the ubitx side to a dpdt switch With the switch in one position it is in digital mode taking over control for the mic and speaker. In the other mode the radio runs normally  Ran pig tails out to the desktop computer sound card. and keep the usb cable plugged into the computer.  using the CEC firmware.

Re: Looking for a single row 16pin ribbon cable source #parts


#bitx40 #bitx40help bitx 40 Amateur radio kits world wide kit questions. #bitx40 #bitx40help


A little background
I was given a bitx 40 for a gift from my brother. I'm a tinckerer  by nature so this makes sense. However, electronics are kind of new to me.

Since this will be my first HF rig I opted to do a clean build. I ordered a model II case from amateur radio kits. The kit is cut to use a baofeng type ptt mic, the kit also has a gain control. It came with 10k pots x2, and a 100k pot. I. Not sure what pot goes where. I'm also not sure how to wire in the gain control. Can i get some guidance. 

Thanks for the help.

Re: A friendly suggestion for Farhan.

William Londree


Thanks for your comments on small transmitting loops.  Seems to require a lot of work to get one working well. They are quiet on receive for sure but lots of Monkey Business to change frequency. Seems like an end fed vertical with an auto tuner might be more practical as a Stealth Antenna.  Just my 2 cents worth.



Re: Low Power Output for Hendricks BitX20A - Watt meters and Scope readings do not agree.... #bitx20

Jerry Gaffke

Correction, 10x does not work, 1x does.
10x would read double if that 9meg resistor inside the probe was more like 4meg.
And that could easily be measured with an ohmmeter from probe tip to bnc center pin.

On Thu, May 17, 2018 at 09:58 pm, Jerry Gaffke wrote:
And that since the 10x probe works, the scope is doing fine.

Re: Low Power Output for Hendricks BitX20A - Watt meters and Scope readings do not agree.... #bitx20

Jerry Gaffke

Very weird, your math looks right to me.
Could be a bad scope probe, have you tried more than one probe?
Could be a bunch of bad scope probes.

You have 4 measurements saying around 5 Watts and one saying 12 Watts.
My bet is that it is around 5 Watts.
And that since the 10x probe works, the scope is doing fine.

If your scope is one that attempts to read the switch and scale the 1x vs 10x readings for you,
could be that the scaling feature is hosed.

Not much going on in a scope probe:
In 1x mode, my cheapo scope probes show about 100 ohms from probe tip to BNC center pin,
that 100 ohms might be there to prevent massive currents when I do something really stupid.
In 10x mode, it's 8.9 meg.
In both cases, it is almost certainly driving a 1 meg load inside the scope, just like the link above says.
Would be interesting to replace your 1x probe with a short piece of coax.
Or maybe just a twisted pair of hookup wire.
Keep it below a meter in length to avoid trouble with reflections at 14mhz.
Then try adding a 9meg series resistor, see if it behaves properly as a 10x probe.


On Thu, May 17, 2018 at 09:13 pm, ab2ts wrote:
What am I missing?

Re: rough draft of how to connect BITX to PC for digital modes wiki

Joe Puma

Sounds like a good setup. I’ll be doing something similar. 

On May 17, 2018, at 9:08 PM, atouk <atouk@...> wrote:

I followed a similar approach.  Mounted a 4 port usb hub inside the case.  One port for the radiuno, one for a 6 buck usb sound dongle, two free for future use (rtl dongle for panadapter and maybe a pi0 for for something in the future).

I also used an Easy-Digi board simply because I prefer to have the radio as electrically isolated from the computer as possible.  The advantage of the USB sound dongle is that the radio gets it's own dedicated audio in and out channels. This way I can have WSJT-X running and not lose my main PC audio.   Disadvantage?  I used an unpowered hub that puts a load on a single USB port with the RTL dongle plugged in.  I'll change that later.

The only thing I had to do to tame the audio is to put a 330 ohm resistor across the output side of the audio out (dongle mic in) to make the volume adjustment smoother.

I run the CEC software to control freq changes and transmit from WSJT-X via CAT control through Onmi-Rig.

On 5/17/2018 8:45 PM, Doug W wrote:
It seems almost every day (or hour) someone has a question about connecting their radio for digital modes.  Following are my cobbled together notes that if the group deems worthy could be the start of a wiki page on the topic.  My concern is my use of a TRRS jack might be too specific, but at least this is a place to start.  Your feedback is welcome.


There are many different ways to pair your radio’s audio and ptt circuits with a computer to work digital modes.  This is not a discussion of all the different ways.  This is how I did it.  Most of the information is readily available if you search this list and online.

I'm using an Easy Digi kit for switching PTT and isolating Rx audio.  I found the loss was too high on the Tx side so I'm going right from the sound card to the rig for Tx but I will describe using both sides of the Easy Digi below.  I set up my radios with a mono jack for the speaker and TRRS for mic/PTT and corresponding cables on the Easy Digi so everything is interchangeable.  I'm using a USB sound card and an FTDI cable.  I have the sound card and FTDI cable plugged into a small unpowered USB hub with the Easy Digi hot glued on top with the cables all hot glued for strain relief.  It is ugly as sin but sits out of sight and works.  There are links below to all the parts I used.

Pop the cover off the USB sound card and desolder the two audio jacks.  Cut two pieces long enough to go from the sound card to the Easy Digi off the mono cable.  It is 6’ long, you have plenty to spare and it is good shielded cable.  Solder the cables where the jacks were and route them out the holes in the case where the jacks were.  Now solder those cables to the corresponding spots on the Easy Digi.  Mic from the sound card to Audio to PC on the Easy Digi and speaker on the sound card to Audio from PC.  Now solder the audio cable with plugs to the Easy Digi board.  Audio to your radio’s speaker via the mono cable and Mic to your radio’s mic via the 4 conductor cable if doing it like I did.  The last connections are from the FTDI to the Easy Digi and the Easy Digi to your ptt.  Cut the RJ45 connector off the FTDI cable and connect the following cables to the Easy Digi, Black to DIG GND, Green to DTR and Brown to RTS.  Those are the only wires you will use in that cable.  Now connect PTT HI on the Easy Digi to your PTT wire and PTT GND to your PTT ground.  Both of these are also part of the 4 conductor cable.  Now plug the FTDI cable and USB sound card in the USB hub and connect the hub to your computer.  If you are using Windows, your machine should set both up without issue.  Connect the mono jack to your radio's speaker jack and the TRRS plug to your TRRS jack or however you have your mic and ptt connected.

Assuming you are using WSJT-X, in settings under the radio tab select RTS for PTT method and whatever port the FTDI adapter cable shows up on.  With a dummy load connected to your radio click the Test PTT button several times to make sure it toggles Tx on and off on your radio.

One last very important thing.  The heat sinks on the IRF510’s are sized for casual voice and cw work not the full blast usage of digital modes.  Make sure you have a plan to deal with the heat.  There are many other posts on heat sink ideas.  I have found even a little air flow from a small fan makes a huge difference.

Following are the parts I used:


Easy Digi

mono cable with plug

4 conductor cable with TRRS plug

TRRS jack

USB sound card

FTDI cable (do not buy a cheap TTL adaptor, they do not put out high enough voltage for the opto coupler on the Easy Digi)

USB hub

I found this breakout jack helpful for confirming the wires on the 4 conductor cable before soldering up the TRRS jack


Re: share your BITX success stories

Jerry Gaffke

Yup, I have no idea why they come mounted sticking out the side.
If you wish, once flipped you can keep that LM7805 cool by soldering the tab to the Raduino ground plane,
though somebody once pointed out that the heat will cause the 25mhz oscillator to drift a bit more.
A 25 to 50 ohm 1/2 watt resistor, perhaps on the bottom of the uBitx, in series with 
that 12v line into the Raduino will reduce the heat at the Raduino.
On the Bitx40, it was necessary to add caps on that 12v line to keep LCD updates on the
Raduino from getting into the 12v rail of the main board and creating hash in the receiver.

I've added a diode on the Raduino board between the incoming 12v pin and the LM7805,
after first cutting that trace.  Provides reverse polarity protection, which the LM7805 does not.
Also, when powering the Raduino from the USB cable during downloads, that 5v
goes back through the LM7805 and powers the radio, which is ok I guess if you want to 
listen to the SW bands while downloading but seems it might cause trouble.

On Thu, May 17, 2018 at 07:54 pm, ajparent1/KB1GMX wrote:
Flipped the 5V regulator around so it doesn't hang off, my case needed that bit of space for a really
good encoder.

Re: Mic doesn't work in bitx40 #bitx40


I cant see any attachment. Just google and you will see what they look like.

Check your polarity of connection.

At 17-05-18, you wrote:

Thank you for your reply..

What is difference between dynamic mic and electret condenser mic? Do they look a like in shape? The one I bought is look like this[] [] ..

Re: uBitx diagnostic document from Facebook group #ubitx

Tom, wb6b

Thanks to Ufi Auttorri for creating this guide. It was certainly a lot of work to do this. 

Low Power Output for Hendricks BitX20A - Watt meters and Scope readings do not agree.... #bitx20


I solved my stability problem for the Hendricks Bitx20A  kit by applying the Martiens mod.     Now I need to resolve a low power output problem.   I had been just calculating the power output from my peak to peak O-Scope readings with a 10x probe.   However I notice that while I had 70 VPP on the scope with the 10x probe ( ~ 12.2W = (70^2)/400 ); my wattmeters both read a much lower 4 to 6 watts.   My wattmeters are a NorCal QRP Club watt meter and a Heathkit HM-9 QRP Wattmeter.   I am driving the microphone input with a 600 Hz phase shift sine wave oscillator.

Interestingly, when I switch to 1X on the probe my reading drops to 42 VPP which calculates out to 4.4 Watts and is more inline with the external wattmeters.   My scope is a new Siglent 200 MHz dual trace digital unit, with stock 10x/1x probes.

I have been reading up on scope probes and it seems that my 200 MHz probes are good to 200 MHz only in the 10x position.  In 1X the spec says 6 MHz, well below the 14 MHz carrier.    Based on this alone I would tend to accept the 70 VPP reading as accurate and accept that I am getting 12W out.    However given the lower readings from the external wattmeters I am not sure what to believe.

I have a homemade -20 db coupler that when terminated to 50 ohms at the tap and fed to the scope with RG-58 also agrees with the lower power output.

My older 20 MHz analog scope agrees with the lower 42 VPP / 4.4W readings independent of the 10x/1x setting.  (Calibration of this scope is reasonable but not traceable. )

All readings into a 50 ohm dummy load.

What am I missing?

Re: Raduino not working 0 Volts on Pin 6 (red wire) #ubitx-help #ubitx

Jerry Gaffke

I am (unfortunately) counting in from the right, so my pin numbering 
is reversed from that shown at

On Thu, May 17, 2018 at 09:02 pm, Jerry Gaffke wrote:
I've got my uBitx Raduino totally unhooked from the wiring harness and the uBitx board,
laying flat on my desk.  Have a USB cable to a laptop to power up the Raduino.
Using a corner mounting hole of the Raduino for ground, I see 4.6 volts on the
first four pins in from the right on the top connector (ENCA, ENCB, FUNCTION, PTT).
The 5'th is ground, so I see 0 volts there.
The 6'th is 5 volts, and I see 4.7 or so because of a diode drop in the Nano.
The 7'th and 8'th are analog pins without pullups, so are pretty much undefined.

Re: Raduino not working 0 Volts on Pin 6 (red wire) #ubitx-help #ubitx

Jerry Gaffke

Yup, this one has been hard to follow.
Let's keep this thread going, seems a fine title for it.

Doing a search for "Rogier", I find these:

I'm assuming all his posts have been signed "Rogier".
It seems he still has the original firmware installed, the Raduino worked at first, 
but now it powers up with a display of "LSB A : 7150.000" and fails to respond
to the function button or the encoder or the PTT switch.

He also reports that    "There is 0 volt on pin 6 (red wire for the funktion button)
to ground on the yellow wire (pin 4) or common ground on the chassis."

His iMac does not see the Raduino when hooked up with a USB cable, but then 
that's not unusual.  Many possible reasons for this.

I've got my uBitx Raduino totally unhooked from the wiring harness and the uBitx board,
laying flat on my desk.  Have a USB cable to a laptop to power up the Raduino.
Using a corner mounting hole of the Raduino for ground, I see 4.6 volts on the
first four pins in from the right on the top connector (ENCA, ENCB, FUNCTION, PTT).
The 5'th is ground, so I see 0 volts there.
The 6'th is 5 volts, and I see 4.7 or so because of a diode drop in the Nano.
The 7'th and 8'th are analog pins without pullups, so are pretty much undefined.

Be very careful when probing the 6'th pin that it does not get shorted to adjacent pins
by the probe, but if you see around 4.7 volts there that will verify that the meter is set up correctly.

If the Function button pin is low and the others high, could be there is something like a piece of wire
or a glob of solder on the Raduino that is shorting it to ground.  With power off, how many ohms
from the Function button pin to ground?  I see several mega-ohms.
A shorted function button will put it into calibration mode, and it may be waiting for the function
button to be released before updating the display.

If all four of those pins on the right side are low, that suggests more serious trouble.
Perhaps the flash program in the Nano got corrupted?  (I doubt it!)
Perhaps the IO cells into the Nano got blown  (Not all four!)
I'm betting the other three pins are high, and the Function button pin
is getting shorted low somehow, and thus hanging up the processor.
Jerry, KE7ER

On Thu, May 17, 2018 at 07:37 pm, Gary Anderson wrote:
Rogier has a few threads open on his problems.  Casually, hard to keep up with where he is at the moment.
He has shared more information than is contained in this thread.
I usually _try_ to look a threads I've responded to, to see if progress is made or if additional inputs  / coaching might be helpful.
I can see how using non threaded email, one might not understand this perspective.
So, please if you have an issue where others are trying help. Please stay on the same thread e.g. subject line.  Easier for others taking their time to try an help.

Re: share your BITX success stories


I've been working FT8 for a few days on my shiny new uBITX tied to a homebrew G5RV set up as an inverted v.  Just finished a 20m QSO with Tasmania.... thats over 9000 miles on just less than 9w! Amazing little rig!

73's de W5JXN