Hi John, The pi-network is a LPF, of course (unless we are dealing with a real antique using a push-pull PA with a symmetrical tank circuit). But sometimes additional EMC (TVI) filtering is required. In my view, there is really no excuse for a 6m tube radio in this day and age - but that's a discussion for another evening. Cheers for now, 73, Adam VA7OJ/AB4OJ -----Original Message----- From: yaesu-bounces at mailman.qth.net [mailto:yaesu-bounces at mailman.qth.net] On Behalf Of John Sent: 4-Feb-09 16:25 To: yaesu at mailman.qth.net Subject: Re: [Yaesu] unfiltered 6M tube radios????!!! "with a tube transmitter you need an external L.P. or B.P. filter, with solid state it's built in." Now that's an interesting factoid. Seems to me most tube final rigs have a Pi net output tank, which is "built in". John K5MO ______________________________________________________________ Yaesu mailing list Home: http://mailman.qth.net/mailman/listinfo/yaesu Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Yaesu at mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html