On 8 Feb 2013 at 21:42, Geoff wrote: > For G&G try a 6AB7 and 6AC7 if you can work out a quick way to solve > the filament issue and compare to the mushroom. > > Carl Actually, the 'shroom' is a pretty good tube....ifn you can find one for a reasonable sum now. I have looked for 717As on eBay and have had difficulty. Ken W7EKB