Spurious 2

My new spectrum analyzer shows the same spurious signal levels the PRC-100 does. So they are real.

I got rid of one of the strong spurious signals. It was caused by oscillation.

I checked the output of the PLL. It shows two strong -15 db signals. One 2 MHz below carrier and one 2 MHz above the carrier. This explains some of the spurious in the output. I have no idea why the PLL generates those signals. Maybe the VCO is somehow modulated (AM of FM) by one of the digital signals.

The harmonic are too strong even though I use a 10 element filter. I have checked the component values. They are OK. I will change the filter into a half wave filter and improve the layout of the components. If this does not help then I will use different capacitors. Capacitors may behave as a inductor at high frequencies.

A different problem is the PSU. The transformer can not deliver the current needed for 5 watt output. In fact it can deliver it but it gets too hot and voltage drops too much.