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[CQ-Contest] Collins Filters in Contest Rigs]

Subject: [CQ-Contest] Collins Filters in Contest Rigs]
From: headrick@radar.nrl.navy.mil (Jim Headrick)
Date: Tue Aug 11 09:28:09 1998
It may be of interest that mechanical filters are a component that hams
with metal machining capability can design and construct.  The Collins type
employing "drum head" vibration mode might be a little tricky, but a simple
transmission line approach using compression or torsion vibration is
straightforward. See:
   "Magnetorestriction Devices and Mechanical Filters for Radio Frequencies"
   Parts I, II, & III  QSTs June, July, Aug 1953 by Roberts.
Suitable metals have Qs somewahat smaller than that of quartz, for example:
   Aluminim          4000
   Dural             8000
   NiSpan C           900
   Srainless steel   1500
Robert's filter characteristic design approach examples were analogous with
transmission line section filter design.  Get the bandpass and skirts you
want!
73 Jim


******************************************************************
*      Jim Headrick (W3CP) --->  headrick@radar.nrl.navy.mil    *
******************************************************************




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