开云体育

Ooops should read pulldown as diagram.

Most of the code at the moment is display stuff. The icon.h can be deleted I suspect as it was development penguin pic but i didn't spend time looking too hard at the code. It could do your head in !

Are you using this on the bitX as is, or are you building a featured multiband bitx.
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Rob G4NQX

I have replaced the IRF510 and this what I found with a cheap Chinese ESR component tester. The original had C=388pf, Vt= 3.7. Replacement has C=1.13nF, Vt= 2.7. Upon the first key up, the speaker screeched and the display dimmed out to blank. I had to turn down the Bias by 25% to make it work right. Retested the PA with 10A setting on MM, set it to 00.10, shouted radio into mic and it read as much as 00.30. The monitored signal sounded a little less buzzy and louder. And read as much as 3 watts on meter. And the heatsink got warm. All with basic 12V shared.

I read some older posts about low PA output, that sounded like mine, and found one from Farhan saying 1 amp is the peak. The multimeter might not be measuring fast enough.

I think it's an improvement. But just a small one.

Can some of the people who had this issue comment please?

He has them as pullup via 10k resistors,

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Rob G4NQX

Made two ugly AGC circuits for my BITX40s. ?Now audio in each is very smooth and even.

Very worthwhile when using phones. ?See photos.

Cheers - Noel

I have been following PD8W (Willem) progress on his build out of a lcd display/si5351. His code and hardware are listed at PD8W.com. After some hard work I have the display working - and looks like his does on his web site. I am at the point where he is using momentary pushbuttons to cycle selections from the screen however am a bit lost as to how the buttons are actually wired up. I sent him a couple of requests for help but he must be out of town as I haven't gotten and feedback.

Could someone take a look on his web page to see what I need to do? The sketch is also there and like I said it compiles. My first issue to overcome what understanding how to wire the lcd and found that in the mcufriend ino. Woohoo the display showed up on the lcd.

Let me know if you need anything further. Note - I did hook it up to the bitx and the encoder does change freqs so that part is also working

73

Art

DuWayne,

Does the graphics library speed up the graphics by a significant amount? ?? It certainly looks interesting.

I followed your journey with the SNAjr with interest.? I was doing something similar but eventually made up the Simple Scalar Network Analyser as it met my needs.
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Rob G4NQX

I thought the BITX40 PC board stand-offs would be suitable earthing points.

But there is no continuity between them and the battery or psu ground.?

Even the DDS stand-offs are not connected to battery ground.

I made the AGC circuit and used a stand-off for earth but it didn't work.

Then I connected it to battery earth and it works fine.

What are the consequences of grounding the stand-offs to battery / psu earth?

Thanks - Noel

l

The hour is to debug an amp. ?Getting all that going on the Raduino and sorting out complete test procedures for the Bitx40 would take a month or two. ?Designing it is not trivial, but once done it would be very cheap to reproduce. ?All these tools would be available to the experimenter for other projects. ?Could also be a standalone board as you say with Si5351, display, and Nano also, but some of the trivial stuff may as well be on the main board so nobody is sitting on their hands for an extra month.. ?Just an N5ESE type RF probe sitting out on a corner of the board would be very nice. ?There is electronics out in the world designed to be easily self-debugged for most problems, and it's a joy to butt heads with. ?Most projects, commercial or amateur, simply don't put the time into it, and most consumers wouldn't bother to mess with it anyway. ?But on a significantly complex project like this with thousands of copies going out to experimenters, we either put the time into tools, or put way more time into playing wack-a-mole as the various problems come up. ?

Just because you have not heard of this being done does not mean it is unreasonable. ?How would you solve the issue of some new ham with a voltmeter and a Bitx40 that doesn't quite work?

Jerry, KE7ER

Rob,

This is GREAT. Please email me (kc7rys @ gmail dot com) if you don't mind, I'd like to discuss a way to make this available for anyone, not just members of the group, if you're okay with that.

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Ryan Flowers KC7RYS?

But it would take an hour to figure this out if we had a few extra R's and C's and a bit of Raduino code up. ?Not a week and $1000 worth of lab gear.

?Well, why not just go ahead and figure it out and post your work to the group? I've never heard of a kit or fully-wired rig come with such rudimentary test facilities before, so what you ask borders on the unreasonable (especially since you've already proposed it before). If "green squirts" will use the BitX40 as a first experience in homebrew experimentation, then they will need some test gear that can be used on other projects, not built into just one. The test functions you propose could readily fit on a small stand-alone pcb, and as you suggest would not take much time for a more experienced Ham--such as yourself--to design and offer, either for sale or as an open-source design.

73,

Todd K7TFC

As I have said several times already, I'd like to see these boards going out with some basic tools. ?

1) ?1khz square wave out of a Raduino digital pin to inject into the microphone, with suitable attenuator.?

2) ?Wide ranging RF from a spare Si5351 channel, with an attenuator that can give a range of output levels.

3) ?An RF voltage probe, such as the one N5ESE described. ?That design has been around for most of a century.

4) ?A low pass filter to look at DC levels in RF circuits

HFSignals could make money selling those parts in a bag for a dollar as an option with the Bitx40, to be dead bugged into the ground plane somewhere. ?It's a dozen resistors and caps and a schottky signal diode. ?Ideally, the board someday gets laid out to have those parts always in place, so we can just tell folks having trouble what gets shorted to what and where to measure with the rf probe. ?Some minor adjustments to the Raduino code would be needed to get the two signal generators up, they would normally be shut down to avoid crosstalk.

Perhaps if I ever get a Bitx40, I'll get some of that going when I have some time. ?And write up a debug procedure.

Could be that R136 between Q13 and Q14 in the final got left set too low (or has a bit of dirt on the wiper), that determines the drive level into the IRF510. ?And twiddling that pot is a lot safer than playing with 20v into the IRF510. ?But remember where it was set, it was more than likely set there for a reason.

This post has a simple oscillator that VE7BEE successully used for transmitting CW. ?Perhaps build that up and wire it to the mic input. ?Should give 6 or 7 watts out the final. ? ?/g/BITX20/message/20638?

From my simulation, it looks like you should get full power out to the dummy load if you inject around 0.1 volts pk-to-pk at 7.2mhz into the base of Q13 through a series 0.1uF cap, and with the drive level at R136 set to full throttle. ?That and the numbers in my LTSpice simulation post should allow somebody with a scope and a 7.2mhz signal generator some idea what an amp is to figure out if your final is working properly. ?

But it would take an hour to figure this out if we had a few extra R's and C's and a bit of Raduino code up. ?Not a week and $1000 worth of lab gear. ?And so long as I'm on this rant, will reiterate that I'd like to see pads for a prescaler and an AD8307 on the main board (and parts available in an optional bag), so we could include an freq counter and a Sweeperino and the ability to look at low level RF in that tool kit. ?Oh, and that capacitance meter of post 19453, required no additional hardware. ?Measuring voltage on a Raduino ADC pin would also be very useful in the field. ?This is aimed at budget minded experimenters, not appliance operators. ?Nothing is quite so discouraging to some green squirt as to be told "Oh, it's easy, read this book, you'll figure it out.". Sometimes it isn't easy, especially if all you have is a voltmeter, and your dad works sacking grain. ?Some of us can still remember having been there.?

Jerry, KE7ER?

Hey Jerry this is exactly what I was thinking when I got up this morning. Jerry-"Or your audio level is way down (bad microphone?) so you don't have enough drive into the final. ?A low audio level would suggest the final has not much to do though, and thus the current into the IRF510 would be stuck around 100ma". ??Aside from trying a different electret mic, how could I test the audio input circuitry? I don't know the stages of this board, but I am able to follow and understand the instructions thus far. Someone give Mr. Farhan a poke and send him over here to tell me what to do.

As for a scope I don't have a real one, I have a homemade "Sound card oscilloscope" I made from a Make Magazine project.?

I am going to postpone the AMP replacement for now.