Re: Is push pull hf amp has higher spectral purity


The stock Bitx40 has a problem with the 7.2MHz birdie not only on receive but also it produces a spur on transmit which does not meet fcc spec.
You could use it on 7.1MHz and below or change the vfo to high side and move the carrier oscillator to the other side of the filter (Allard's software). Whether you can do that depends on the xtal filter in your Bitx40. You may get lots of carrier and poor sideband rejection.
The Bitx is a good entry into homebrew. You might get away with using it barefoot but take care if you want to push to higher power.
73 Brian.

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