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 Rodif 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
