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I'm working on a Bitx40, that was initially purchased without the Raduino; but now I have a Raduino and I need to verify that the DDS is correctly driving the mixer. On the Bitx40V3 schematic, I removed L4, C95, C93, C91, and C92. I connected the Raduino CLK output to connector DDS1. I was messing around in that area a bit, and I suspect I've messed up something, so I would like to ask if someone can post a waveform from the collector of Q7. What I'm seeing is at the right frequency, but it only has an amplitude of 2Vpk-pk and a DC offset of +10V. I expected to see a wider swing. Any scope shots or description appreciated.

Thanks,
Jake

Here is my waveform at Q7 collector. Is this normal?

I don't have a scope but I think that would be normal. In the uBitx Farhan drives the diode mixers from the Si5351 (3v output) via a small attentuator pad. In the Bitx40, Q7 to Q9 are left over from the analogue vfo. If you wanted to drive with a cleaner square wave you could rebuild it to be the same as the uBitx. If you want to really clean up the 7Mhz output (and get rid of the 7.2MHz birdie) you need to use the vfo at 19MHz and change the 12 MHz oscillator to be on the low side of the IF.
73 Brian.

Jake, Attached is what I have at the collector of Q7. So yours is probably fine. I avoided removing anything, instead I directly inject the signal into the base of Q7, that's probably why it looks cleaner. That did away? with most of the "birdies", too. Yours is working OK, right? If so, don't worry. 73, Don, ND6T

On Fri, February 23, 2018 23:48, Brian wrote:

If you want to really clean up the 7Mhz
output (and get rid of the 7.2MHz birdie) you need to use the vfo at

19MHz and change the 12 MHz oscillator to be on the low side of the IF.

Raduino v2 does this.
Download it from

73 Allard PE1NWL