Recent content by WH7U

The new version solved the problem. I have it running now. Thank you Frank! Now I have to learn how to use Tisho's menu! I am embarrassed to say that I figured out the problem with the LO birdies and the problem was me. It turns out that the FFT mode in my new oscilloscope does not include an...

Interesting. Perhaps it is because I am using the 8mA setting on the Si5351 or have a termination problem. I am also running the LO through a length of coax - I may have an impedance mismatch. I will investigate later today. I too was alarmed at the temperature reading. But if I put my finger...

For the new software, I get this error compiling because the define is only called with HARDWARE_DO7JBH_T41 enabled. 73, Bill WH7U

Oh nice. Preselectors are great. I think a good set of filters plus a preselector might be a good idea. The only people who don't like preselectors are very lazy people :-) Thank you for updating the code. I am excited about Tisho's menu assistant and tuning steps and the bug fixes! I have not...

I think this is probably the best way to go. The narrow IF could have smaller integrating capacitors so a naturally narrower bandwidth. I know that this project was not meant to compete with the top end receivers out there. But you have built all the difficult pieces in DSP - the performance of...

Thank you Karlchen. I did not know wideband transformers were available.

Frank, you are a genius! I found that my Si5351 drive strength was set very low. I turned it up to 8mA and added a 50 Ohm resistor to my receiver and it came alive! It is working much better now and all the weird noise is gone. Thanks for the tip. In case anyone else might be having this...

On another subject, I wanted to see if I could make a transformer that covered from 100 kHz to 200 MHz for the input to a wide-band QSD. This is a very large bandwidth for one transformer. A 2-core transmission-line transformer can provide good unbalanced to balanced 50 Ohm to 200 Ohm very...

Hi Frank, Si5351 I think you are right. Thank you for the link - I reviewed it and also re-read the data sheet. When I get back to the radio, I will check to see that I have the setting at 8 mA. It sounds like I don't. IF: Youngblood explained the compromise in IF bandwidth in part 4 of his...

@DD4WH and everyone. I am not having great performance from my modified QRP Labs QSD receiver and Teensy setup. I finally bought myself an oscilloscope, an RF generator, a large pile of filters, a small pile of attenuators, and a step attenuator so I can do some actual testing to figure out what...

Mirror rejection is the same as image rejection. I think it is more of a DSP term than a radio term, but it means the same thing.

I didn't measure it yet. I need to get some more attenuators. I used to have a whole bunch of them but now I only have a few.

Nice work Tisho! Sounds like your radio is working well. I like the menu - it looks great.

Ok Frank. I figured out how to make complex bandpass filters. After fruitless research and less-fruitless experimentation, it is actually embarrassingly trivial. I don't know why this information is so hard to find. I can't find any good reference material on complex filters - just a bunch of...

I recreated the filter kernel in calc_cplx_FIR_coeffs in MATLAB and plotted the response. I see now how it is a Hilbert filter and Bandpass filter both. This is for 96 kHz sampling rate, decimation by 8, and an IF frequency of 24 kHz (that gets decimated down to 3 kHz). I set the bandwidth from...