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ubitx v3 carrier burst #ubitx #v3

Christiaan PA3FUN
 

Hi All.

I'm using my ubitx v3 for a couple of months now. I'm primarily using it for CW using the official 4.3 code-base (nót Ian's CEC code) and found quite some "room for improvement".

First of all I added setup-code so the output of the first mixer can exactly be mixed onto that first IF's center frequency. Just in case that first IF is nót exactly centered around 45MHz. In the same way I added setup-code so the output of the 2nd mixer ends-up exactly at the right place regarding the 12MHz xtal-filter. Using both functions it's easy now, just using your ears, to optimize the radio's performance.

I've also added some code so as to calibrate the SI5351A's frequency so that when you tune to f.i. 3.560KHz you're exactly there. For this you do need however a frequency-counter or another (properly calibrated) HF-radio.

Another thing that bothered me was the fact the radio generates a short burst of "spurious" every time again upon it's first (CW-)key-down. I did some research and found out / can confirm this is caused by too slow discharge of two electrolytic caps (C52 & C64) causing both the TX- and RX-circuits between the 1st and 2nd filter to be concurrently active causing an oscillation that's fed to the then active TX-amplifier-stages. Short-term solution: remove these two caps from the PCB.

Besides the above points I identified a number of bugs.

I'm not (yet) familiar with how Github works; should anyone be interested in this code (and using uBitX v3 hardware) just let me know.

73's Christiaan PA3FUN

 

 

Bill Cromwell
 

Hi Christian,

I would like to have a copy of that. My email should be able to handle it if yours can.

wrcromwell@...

73,

Bill KU8H

On 4/14/20 6:57 AM, Christiaan PA3FUN wrote:
Hi All.
I'm using my ubitx v3 for a couple of months now. I'm primarily using it for CW using the official 4.3 code-base (nót Ian's CEC code) and found quite some "room for improvement".
First of all I added setup-code so the output of the first mixer can exactly be mixed onto that first IF's center frequency. Just in case that first IF is nót exactly centered around 45MHz. In the same way I added setup-code so the output of the 2nd mixer ends-up exactly at the right place regarding the 12MHz xtal-filter. Using both functions it's easy now, just using your ears, to optimize the radio's performance.
I've also added some code so as to calibrate the SI5351A's frequency so that when you tune to f.i. 3.560KHz you're exactly there. For this you do need however a frequency-counter or another (properly calibrated) HF-radio.
Another thing that bothered me was the fact the radio generates a short burst of "spurious" every time again upon it's first (CW-)key-down. I did some research and found out / can confirm this is caused by too slow discharge of two electrolytic caps (C52 & C64) causing both the TX- and RX-circuits between the 1st and 2nd filter to be concurrently active causing an oscillation that's fed to the then active TX-amplifier-stages. Short-term solution: remove these two caps from the PCB.
Besides the above points I identified a number of bugs.
I'm not (yet) familiar with how Github works; should anyone be interested in this code (and using uBitX v3 hardware) just let me know.
73's Christiaan PA3FUN
--
bark less - wag more