Has anybody had experience replacing 3-500Z zero bias triodes with Tesla RD 500A? They are from Prague, Czech Republic. http://www.electron-tubes.cz/products_f.html -- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com