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"Mike Knudsen" wrote in message
... Long ago, like early '70s, Popular Electronics mag had a short article on how to FM a 6m rig with a varicap diode across the oscillator tank. Very short parts list, and the most expensive item was probably the phone jack for the mic input. BTW, this article suggested FM as a way to reduce TVI -- not clear why it would be less messy on TV picture or sound than an AM signal. SSB was blissfully rare on VHF back then. --Mike K. I never understood it, but it seemed to work: those who tried FM reported that TVI *was* reduced. Since TV audio is FM, albeit at 25 KHz deviation, I would have thought it'd be *easier* to cause interference by using FM. Of course, perhaps it was a "second order" effect: perhaps it prevented *audible* interference, and therefore prevented anyone from identifying the source. I'd think that previous complainents might simply assume that the local ham whom they'd heard on their TV before was causing the picture to roll, but then again, I remember assuring neighbors that "If it was me, you'd hear me talking", so I might be wrong there ;-J. If anyone out there has the authoritative answer, please pass it along: did FM cause less interference, or did it simply prevent the interference from being in the audio chain? Enquiring minds want to know! Bill (Remove ".nouce" for direct replies.) |