Thanks for the info Rob
I’ll take it into the workshop where I have a spectrum analyser and some half decent test gear.
I’m a little unsure though of my use of a varactor diode for RF amp tuning as they are used for doubling and tripling in other applications. I have seen a method of using them back-to-back to minimise odd effects.
I’ve also noticed the comb of spikes but I suspect it may just be overloading.
My SDR Play usually needs from 40 to 80dB of attenuation.
73 Allan G3PIY