Introduction - Ham Radio Projects

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Martein Baker, PA3AKE, is the author of very interesting and known Ham radio project.  Down Conversion Receiver with  H-Mode mixer  is described in detail on his website.  First  results of MarteinĀ“s many experiments with frontend parts were published in 2008. IF subsystem with backend was added  about 3 years later. Now, Martein is working on the remaining parts.

I choose from his detailed documentation:

"The T94-10 based BPF with the FSA3157/T1-6T mixer and the QT crystals hybridized roofing filter together produced a frontend on 40M with a (2.2KHz) SSB MDS of -133dBm and an IIP3 of +50.1dBm. This equals a dynamic range (IMD3DR) of 121.7dB! "

Wooow, more than 120 dB of IMD3 dynamic range....+ 50 dBm of IIP3 on 40 sounds incredibly. Especially if you compare these parameters with most types of factory-produced ham radio equipments. I felt  a very good motivation  to try to built such a good radio....

Hal, EA5GNI, used MarteinĀ“s 500Hz roofing filters in his homebrew receiver:

" Switching to 40M with full activity was and still is a different world! I suddenly could read stations which were in the noise when I switched back to the SSB roofer. It is absolutely true that CW is fun with a 500Hz roofing filter. Even the excellent SSB roofing filter can be topped! Strong signals with 30 or 40db over S-9 just disappear and do not affect the weak signal at all. "

The following pages show some of the results of my work, including measurements, using home made N2PK VNAs and the Signal Hound USB-SA44B
Spectrum Analyzer. The project was implemented without any significant changes from the original.

Picture what we can not see very often....

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