[Amps] Tank circuit Q

Peter Chadwick g3rzp at g3rzp.wanadoo.co.uk
Mon Apr 16 08:13:48 EDT 2007

Tom commented
>They are a sign of bad 
engineering, just as the shorted taps on the toroid were.<
I don't know about Tom, but I've never been a great lover of toroids in tank circuits - there's the short circuited turns problem (although the iron dust toroids generally have a lower permeability, so the leakage reactance is a bit higher which helps), and the there's the problem of ensuring that the material isn't driven too far round its hysterisis curve so that distortion results. One 4 channel HF SSB rig that I worked on (pair of 6146Bs) had toroids: we ended up with 4 toroids, one for each channel - i.e. each channel had its own tank circuit. Originally designed to go to 16MHz we naturally had a demand for them up to go to 24MHz, and then the efficiency got pushed up by going to some air dux instead. Then the receiver image response was a problem so we fitted single crystal filters.
Peter G3RZP: 

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