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I'd add the diode should be after the fuse.

That protects the wires from being burnt up is there is reverse polarity.

One note: Clean the key contacts!? Seriously its a known problem since the telegraph days.
Bounce is a software issue but high resistance contacts should not be.? Its also a painless fix.


Allison

As an aside on power supply filtering, the stock rig has about 'none' and is very susceptible to power supply noise, especially power supplies with switching regulators. There's not much margin for voltage loss in an input regulator, so I came up with a scheme that uses a cheap Ebay boost-buck regulator board and a built-in LiIon battery pack. This provides some filtering, isolation from input noise and the ability to run at full performance from battery even when the voltage drops below 10V.

Joe

The word earlier this week was that uBitx were being shipped from stock; I jumped on this news and ordered one on Monday expecting to see a shipping notification in a day or two.? It seems my card was charged yesterday but I have yet to see shipping information.?

I'm not worried, just curious what the status is.

Kevin
K5KDT

I did two things:

flipped the regulator but left it about .2" above the board.? Check the raduino stck as about 50-55Ma
far from enough to warrant heat sink.? At most its dissipating .6W.? This may be lower as I've lowered
the backlight current.

I also added a series diode (1n4007) on the back of the raduino board (paranoia) for reverse power
protection plus a 100uf cap for noise and spike protection and a .7V drop as well.

While I had the diodes out I added two to the back of the board at the power connector (one for
general 12V and one for the PA12V).? I prefer the polarity protection after the fuse so the power
wires do not burn up and fuse failure is an attention grabber.??

None of these need be in the production or for a cased and fielded unit but if I'm going to be
hacking the board I need protection to avoid painful errors.

There is a lot of check then continue steps.? I do this to insure I haven't broken something
and if need be also to see I've not degraded anything.

Allison

It appears those are just Gerber files, not design CAD files, so they'd have to be viewed in a Gerber viewer and dimensions made with the viewer's measurement tool. I might just as well grab the actual board and measure it.?I want to mount my ILI9341 main-display directly to the new Raduino, so I primarily need the dimension information to be sure the display lines up correctly in the existing hole in the front panel of the rig.

BTW, I considered starting out at the STM chip level, but you can buy the whole board cheaper than you can buy the chip. And you'd have to put all the necessary 'glue' around it and then build it and burn an Arduino compatible bootloader into it. Also, an FPU is primarily useful in DSP applications, and I see that as being a separate unit, so I'm going the Pill route.

Joe

Hello.? If not too late, could I be put on the list for one each of the boards/kits.? Thanks.? de NF5K

Just to clarify: is this ONLY for BITX40? If I have the uBITX, how would you know?? :)

The link in Nik's post points to a project at EasyEDA showing his board layout,
has a "Download Gerber" button.? Though you will probably have to set up
an account at EasyEDA to have the priviledge.? I have not.

Anyways, you could correspond with Nik, he seemed to be trying to make?
this project publicly accessible.? Though I suspect he just used
his own calipers to get the numbers.

Jerry?

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

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.

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.

Joe
W3JDR

Thanks Doug, your notes are very helpful.

73, Dennis
W7DRW

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.??

Regards,
Gary

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.

Allison

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.

How about that one?

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.

Allison,

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.

Bill

W6SDI

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.

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.

Jerry