Of course, that linear amp should be vaguely linear, and not flat-topping your 1.8mhz into a square wave.
Could be that it will clean up considerably if you turn down the gain at RV1.
But even if you get it looking like a sine wave on the scope, will still need the 160m filter.
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On Fri, May 4, 2018 at 10:36 am, Jerry Gaffke wrote:
Not unexpected, looks vaguely like a square wave, which is what you get from a sum of odd harmonics.
The relays are selecting the 80m low pass filter, with a corner about halfway between 4mhz and 7mhz, so 6.0mhz.
Third harmonic of 1.8mhz is 5.4mhz, which is going to get passed quite well by your 80m filter.
The push-pull amp probably nulls out most of the second harmonic.? So we get the fundamental and the 3'rd harmonic.
Hook that up to an antenna and you will be getting heard quite well on both 1.8 and 5.4 mhz.
