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The Arduino (ATMega328) can count external clocks up to 1/2 the clock used to run the chip. With a 16mhz clock for the ATMega328 that would be external frequencies up to just shy of 8mhz can be

Can you hear static or at least an increase in background noise as you plug the antenna in? Perhaps bring a wire from the antenna connector over near the 25mhz crystal of the Si5351 on the Raduino,

My son did not have time to go into great detail. I'll find out and report it later. My son lives about 3000 miles away (KY to CA) so while swapping radios to see if the problem follows the radio is a

I put a home made broadcast band filter in the rf Path of my one bitx and a kit one in the rf path of my v6. They kill broadcast AM interference from KDKA which is a 50kw blowtorch not 10 miles from

Maybe try swapping uBitx's with your son. See if the problem follows the rig or stays with the QTH. Out of curiosity, do all these extra carriers move at the same speed as normal signals as he tunes

As many of you know, I gave my V6 to my son in Sacramento, CA. He's an avid QRPer and would rather make a contact with low power/QRP than with a kilowatt. His first impression is that the radio is

This H&P jitter may not matter much if it isn't very frequent. If it's a second or two between updates and the frequency slews at a reasonable rate after an update, the "jitter" should be no more

Hello to One & All... Put together this uBitx . I have double checked all the wiring and all is correct . But when I power it up all I can hear is hiss from the speaker . I uploaded V5 Firmware but

Gareth Evans We have the same last name...are we related? 8-) H&P stabilization is interesting because by default it sets the tuning step size as well as holding frequency drift to around 1 Hz,

Perhaps the Huff-and-Puff stabiliser needs revisiting, where an occasional frequency correction is applied to correct drift? To do this, up to what frequency will the counters of an Arduino work! A

Did some digging into the KD8CEC code.? In that version, there is not a globally defined value for the first IF.? There is in this segment hardcoded if values: Note that there is a different value

Farhan, and others... Designing a free-running VFO is challenging. Good variable capacitors are becoming difficult to obtain. Older Colpitts and Hartley layouts are not as stable as we have become

Farhan, What you say sounds right. There's a reason why people have moved away from analog VFO's, they are finicky. The Si5351 is not necessarily the best choice, just the cheapest and easiest, so it

Jerry, Contrary to a popular opinion, a free running LC oscillator can be the quietest there is. Any attempt that holding it to a frequency (phase locked loop) starts adding to the phase or amplitude

Hello, the project of a Ubitx in module has already been evoked see here: /g/BITX20/topic/71823431 cdt

Gordon, Any assembly can be cut into pieces. Advantage, one can change/ improve a module at its convenience. The best system (in my opinion) is a board with main functions and a bus with several

Farhan, What do you think is the major factor in the relatively poor performance of the Si5351? I suspect it is jitter, not the fact that it is a square wave. The Si5351 is their cheapest part at $1,

Ashar, I agree that a analog vfo would be superior but I have not had much luck building one that was stable enough. That was the reason I chose to use the 5351 or my PLL. Any chance you would share

Barry, I too built a direct conversion transceiver a few months ago. I chose a fully analog design without any ICs. A carefully designed free running vfo is used. It is so stable that I can

Hi fellow DC rx fans. Back in 1992, Rick Campbell had a design in QST for a direct conversion receiver he called the R1. Later he upgraded this to the R2. I have the R1 that I have used the si5351 to