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Re: Resurrection of a developers edition

 

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Very cool, Evan! ?
Thanks for all the advice. ?
I¡¯ll start making measurements shortly, today
I had to do a little bit of reading and thinking about how I wanted to approach this

I¡¯m somewhat of a Neanderthal; I¡¯m still using what I think is the original image because I was familiar with it. But I¡¯ve lost track of some of these little microSD cards in the process of frantically trying to get the raspberry pie working. ?

I had actually managed to create a programming environment for the raspberry 2 ?and had managed to actually compile the code with it but could not get the GTK to run I believe. ?It took quite a bit of work to get a compiling environment

Now that I have a raspberry pi four I¡¯m back to trying to use Ashhar¡¯s code. ?

From what I have gleaned, it¡¯s likely that my hardware now works (at least for receiving). The explanation of the dual pan adapter images seems to be frequency selection for oscillator rather than a fouled up Codec. ?

TXO: ?I¡¯m still using the TXO of the original hardware. Other than a goof I made that blew up a couple of microphone preamplifier transistors, I haven¡¯t lost any known hardware other than 2 ?(precious) raspberry pie fours, and I¡¯m sure I did something to cause that, with all the work I was doing on the +5 internal supply. ?

I¡¯m very suspicious that some of my measured & reported spurious emissions were due to coupling to the 12V RX/RX line that I had extended, to run a ¡°push to talk¡° output. ? ?Since then, I see that people have filtered the +12 supply better, and it¡¯s extremely important in this radio. ? If I can ever get the transmitter working which is likely, I¡¯ll be able to test that theory. ?If my theory is correct that will tell people what to be very very careful about monkeying with, to avoid adding spurious emissions!! ?That¡¯s the best explanation I have for why Ashhar was not seeing anything like what I was seeing


Although there are a lots of bumps in the road, this design is getting more resilient. ? For Ashhar¡¯s sake, I think adding resiliency is very important. ?It will greatly reduce the number of people ?with problems.?

Our local crew (NF4AC / ?NF4RC)put in an enormous effort into ARRL field day, and we came up with a far better score, and huge financial resources went into our effort. >450 vol hours. ? If I can get this little bitty developers edition radio working again, then I will be more interested in pouring more resources into getting a V2. ?

Gordon KX4Z



On Jul 10, 2023, at 06:55, Evan Hand <elhandjr@...> wrote:

?Hi Gordon,

In resurrecting my DE, I found that going to the V2 image and doing updates using that microSD card seemed to fix many issues.??

Are you using a TCXO clock on the Si5351?? The Adafruit clone Si5351 board I put in place of the fried Si5351 and damaged traces uses a crystal as the clock reference.? That is not as accurate as the TCXO used in the stock sbitx.? You can go to si5351v2.c and on lines 45 and 46? change.

//int xtal_freq_calibrated = 25012725; // crystal oscillator?
int xtal_freq_calibrated = 25000000; // tcxo

to

int xtal_freq_calibrated = 25012725; // crystal oscillator?
//int xtal_freq_calibrated = 25000000; // tcxo

Adjust the xtal_calibrated value to be accurate against a zero-beating AM signal.? I have a reference 10MHz signal that I use.? A signal generator you trust could be used, or WWV if you can receive it.? The final value I determined significantly differed from the supplied code's default.

It is a pain you must rebuild every time you make a change.? It would be nice if this were a value in the hw_settings.ini file like the BFO.? I have not yet dug into how that works.

73
Evan
AC9TU
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