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Hi Justin, That article looks interesting. I wouldn’t mind buying one of the PCB’s off of you. How does $5.00 sound, is that fair? I usually look at this group each day so let me know what you

Jerry, I agree with your assessment.? I really need to do the IMD and power tests for SSB. Doing some more simulation, I do believe that increasing R83 to allow for a better filter impedance match is

Actually 80,40,20 are all fairly even. So adjust RV1 or R83 as appropriate for SSB use.

Evan, I have no idea if you will have trouble with IMD on 80m. Increasing R83 would cure IMD and also further improves the impedance seen by the filter, but reduces power on all bands. Could just

Jerry, I did not think of the LPF causing the dip on 30meters.? That makes sense. I will check the SSB signal on 80meters with my RSP1A and the SA software.? The choice would then be to change R83

Evan, The dip on 30m is because it is using the 40m LPF, which must attenuate a 20m second harmonic. But hey, it's primarily an SSB rig. My only concern would be that the big C81 causes too much power

If it's at least a 16 bit machine and either has lots of registers or an easy way to access words in RAM as an offset from the stack pointer,?C is the way to go. This applies to pretty much all

Even though the sources for the Silicon Labs Si5351a chips have pretty much dried up and the remaining stock at some suppliers is being sold at highly inflated prices, we found, thanks to a post by

As someone who started in I.T. on a Mainframe with 16 k Magnetic core memory no disc drives and only ran a single program at a time there was always a bottleneck. Whenever a routine had to run with

I put my v4 back together with the stock L1-4 toroids.? The only change I made was to C81.? I put a 2.2nF in parallel with the 470pF that was there.? Here are the CW results with 12 volts to the

Justin, FYI, There is a Groups.io for that work.? It is here: /g/ucx The original project was called ?CX, which the group felt was too close to the QCX/QSX names that are used by

Looks really cool. Upon reading his explanation of his code, I need to revisit my assumption that writing assembly is almost never worth the effort now days. Although it looks like he put an

After getting my feet wet with the UBITX I ran across this interesting sounding project: https://antrak.org.tr/blog/usdx-a-compact-sota-ssb-sdr-transceiver-with-arduino I sent off the Gerber files and

The AL of a T30-6 core can vary +/-5% of the nominal value, and inductance is proportional to AL. https://toroids.info/T30-6.php Yet another handy factor to blame bad results on. Inductance is

The plot thickens. The most recent observation is that there is a HUGE variation in the inductance of the toroids depending on the turns AND the spacing.? I tested this because my first attempt at

Farhan, Perhaps driving harder will help, worth trying. However, the middle picture of this post shows TP1 when operating 40m CW: /g/BITX20/message/87328 The first image here shows

As Curt found, increasing C81 seems to be key here. The filter and mixer see much closer to 50 ohm loads with the v3 values of C81=0.1uF, R83=10ohms. But v3 had too little power on the high bands. I

I think I am done playing with LTspice.? Here is the circuit I plan to change my v4 to: The LTspice file is attached. I wanted to balance out the input impedance issues with the gain issues at higher

An interesting new contribution by "NerdRalph" - this may help the uBitx Raduino code size - ArduinoShrink?replaces Arduino AVR Core functions with smaller and faster versions. The Arduino Blink

Testing on-air? There's a tuning device that was very popular a few decades back, and schematics are still available online. It uses a 555 to generate approx. a 30% duty cycle CW key-down, and you can