Invar is a special material. It is special that is has very low tempreture expansion characteristics. When used for the tuning rod in a duplexer it will compensate the expansion in the copper center conductor so that the frequency of the cavity does not drift. I calculated a 6m cavity that uses steel tuning rods would drift 50kHz over 30-130 degrees farenheit. With invar this would be more like 1-2 kHz over the same temperature range.
How long are the rods? I could go for some that are in the 5 1/2 foot range. On Thu, Jul 15, 2010 at 10:05 PM, ka9qjg <ka9...@wowway.com> wrote: > > > Glen , I know some will think If I “am to dumb to know what they are , > Then I do not need them . But I still would like to know in layman terms > what is a INVAR Rod if I was guessing Maybe something that goes in a > duplexer > > > > Thanks > > > > Don KA9QJG > > > > *From:* Repeater-Builder@yahoogroups.com [mailto: > repeater-buil...@yahoogroups.com] *On Behalf Of *Glenn Little WB4UIV > *Sent:* Thursday, July 15, 2010 9:31 PM > *To:* Repeater Group > *Subject:* [Repeater-Builder] Invar Rods > > > > > > Does anyone need INVAR rods? > I salvaged some from a TV audio / video RF combiner. > > 73 > Glenn > WB4UIV > > > > >
