When I got mine the heat sink had an intermittent short to ground. Luckily it wasn't dead shorted and I was running it on a current limiting supply. I removed it, filed enough off the bottom to be able to place double layer of tape and then put it back. I'd check to see if you have a short on the heat sink.

?

si5351.set_freq(11998500L*100ULL , SI5351_PLL_FIXED, SI5351_CLK2);

?

That’s the sound I heard when I first powered up my beautiful BITX40. I immediately cut the power, traced all my connections, everything looked great. Cautiously I applied power and turned on the radio, it tuned in perfectly. After some playing around I tried to transmit… nothing. No power out. Well I guess it was the transmit circuits that made the pop sound when I powered it up.

I believe the source of the snap pop (a minor flash too) was close to the PA-PWR input, close to the larger black torrid and the heat-sinked transistor. There is no visual damage on the components or board. Any ideas on how to trouble shoot?

Oh, just a note, the power supply was a powerwerx switching power supply, so nice and clean. Any help would be great!

Thanks!
Josh
KK4LGZ

OK, I'll take a stab at this. ?But haven't compiled and tried it, might be sending you off with a bug or two.

The VFO_A and VFO_B defines are just an integer used to remember what frequency we are currently operating on. ?This is not fully implemented. ?If it were, you could push a button and flip from talking to your friend at 7.175 with VFO_A and see what the traffic net is doing at 7.270, for example. ?Then push the button again and get back to your friend at 7.175. ?Twiddling the tuning knob changes the frequency of whatever VFO you have currently selected. ?There is of course only one VFO, and it always comes out of channel 2 of the Si5351. ?The Nano sketch is remembering those two VFO frequencies, and toggling the Si5351 frequency out of channel 2 when you press the button. ? In summary, your on the wrong track.

Let's assume we leave the VFO at Si5351 channel 2 and put the BFO at Si5351 channel 0. ?Channel 1 is left unused, and is turned off. ?You can probably figure out how to add a piece of coax to channel 0, perhaps just solder it directly into the back of the Raduino board.

Add this code to the bottom of the setup() function in the sketch:

  //si5351.drive_strength(SI5351_CLK0, SI5351_DRIVE_2MA);
  si5351.output_enable(SI5351_CLK0, 1); 
  si5351.set_freq(11998500L*100ULL ,  SI5351_PLL_FIXED, SI5351_CLK2);   

Then wire up your coax as Pete suggested here, and see if it works: ?/g/BITX20/topic/4703461

The BFO frequency is set to 11.9985 MHz. ?You probably want to adjust that somehow until you get the best audio when receiving a station. ?The value is given in Hz with a final L to tell the compiler that this is a long integer of 32 bits, not just 16 bits. ?I'm following Farhan's lead and multiplying that by 100ULL, which is a really big integer of 64 bits (an unsigned long long) but only has a value of 100. ?The extra factor of 100 is needed because the Si5351 library takes frequencies in hundredth's of one Hz just in case you care about being that precise. ?An unsigned 32 bit integer can deal with numbers up to a max of 2**32 - 1 = 4294967295, so big enough to tell the Si5351 about a frequency of up to 42.9 MHz. ?So that code could also be written as 11998500UL * 100, or as 1199850000UL. ?But then I haven't tried it. ?The "U" tells the compiler that this is an unsigned (positive) number so the bit normally used to store the sign (the + or -) can be used instead to deal with numbers twice as large.

The drive_strength line above has been commented out with the two leading slashes. ?If you remove the slashes then the Si5351 will drive your channel 0 coax with a 2 ma output buffer. ?You could also try 4ma and 8ma. ? Not terribly obvious what that value should be. ?Too little drive into the demodulator and there may be intermodulation distortion. ?I doubt there's any consequences for driving at the max of 8ma, those diodes should have no trouble handling 8ma. ?But I could be wrong. ?

Ideally, the 11.9985 value could be changed during the calibration sequence by pressing a button and turning the tuning knob, the BFO frequency displayed in the LCD. ?When the button is released the BFO frequency gets stored to EEPROM, where it can be read by setup() the next time the rig is powered up. ?That's left an exercise for the reader.

Jerry, KE7ER

On Sat, Apr 8, 2017 at 12:35 pm, Jonathan Peakall wrote:?

Getting ready to convert over to using the si5351 for the BFO. I'd like to use rg-174 for both the VFO and BFO lines. The Si5351 has three outputs. The first is already routed on the PCB to the SIP header making it inconvienent to solder coax to it. Is there any reason that I can't use the two other Si5351 outputs that aren't used? That would be easy to solder to. And if so do I change the sketch like:

#define VFO_A 0
#define VFO_B 1

to

#define VFO_A 1
#define VFO_B 2

I've never done Arduino before, but that looks like it to me. Anything else?

Jonathan - KK6RPX

?

Getting ready to convert over to using the si5351 for the BFO. I'd like to use rg-174 for both the VFO and BFO lines. The Si5351 has three outputs. The first is already routed on the PCB to the SIP header making it inconvienent to solder coax to it. Is there any reason that I can't use the two other Si5351 outputs that aren't used? That would be easy to solder to. And if so do I change the sketch like:

#define VFO_A 0
#define VFO_B 1

to

#define VFO_A 1
#define VFO_B 2

I've never done Arduino before, but that looks like it to me. Anything else?

Jonathan - KK6RPX

?

We are using coax to shield the critical signals, not so much as transmission line. ?The coax shield on both ends should be tied to a suitable ground. ?If used on the volume pot (I have no idea if that will help in your particular situation), you probably need two pieces of coax because there are two critical signals.

According to this webpage, RG-174 is 2.55mm in diameter, RG-178 is is the smallest listed at 1.8mm: ?? ? The RG series spec was last updated in 1962. ?I have some nice flexible 1.5mm coax on hand, no identifying marks and no idea what it might be called.

If you don't want to mess with coax, twisted pairs are a good second best. ?Just twisting the wire provided by hfsigs will help, but better to use smaller diameter wire as that allows the wires to be closer together. ?Twist a ground wire with the critical signal wire, perhaps one or two turns per inch. ?In the case of the volume pot, could just twist all three wires together since we don't care if the two signal wires interact.

On Sat, Apr 8, 2017 at 12:45 pm, Jerry Gaffke wrote:

?The impedance (50 or 75 ohms) should not matter much

?

This method is preferred, as it could let you adjust the BFO using the tuning pot just like you currently adjust the BFO.

?

if i use only an Arduino Nano to which Pins do i have to connect the LCD pushbutton and SI5351?

In the Code some Pins are named, but I am missing the connection to the SI5351.

?

Hi, while checking my transmit audio quality (getting muffled
reports), I disconnected my Icom's antenna, set both the Icom and Bitx
(on a 40 meter dipole) to the same frequency and listened to
transmissions on the Icom. What I noticed was an S7 or 8 when keyed
but not talking? In ssb, shouldn't the S meter be close to or at zero
unless modulated by my voice since there is no carrier. Could someone
please check for me in case it's some kind of thing that happens in
such close proximity to each radio. Thanks
Links:
------
[1] /g/BITX20/message/24789
[2] /mt/4816007?uid=236039
[3] /g/BITX20/post
[4] /g/BITX20/editsub?uid=236039
[5] /g/BITX20
[6] /static/tos
[7] /g/BITX20/leave/defanged

Hi, while checking my transmit audio quality (getting muffled reports), I disconnected my Icom's antenna, set both the Icom and Bitx (on a 40 meter dipole) to the same frequency and listened to transmissions on the Icom. What I noticed was an S7 or 8 when keyed but not talking? In ssb, shouldn't the S meter be close to or at zero unless modulated by my voice since there is no carrier. Could someone please check for me in case it's some kind of thing that happens in such close proximity to each radio. Thanks