[ARC5] 10 meter BC-454 - more yet.

[Mike Everette]

This may seem like grabbing at straws... but if you remove the coil rack, and "thump" the coils real good with your finger, and either feel or hear any (ANY) mechanical vibration as a result, this COULD be part of the problem.  It may come from too stiff a wire being used to mount the coils to their bases.  

Believe it or not I have indeed seen this in a home brew VHF converter.

It has also been noted in 40 MHz range (and lower) base-loading coils in LARSEN (yes, I'm naming names!) mobile antennas.  If you thump a Larsen coil, it'll ring like a bell; you can hear it!  For a long time they were air wound with no form.  We had trouble keeping them in tune on our SHP vehicles.  After switching to Antenex aka Laird antennas -- many, many fewer problems.

Are the coils in your receiver air-wound or on the forms?  I forget what you may have said initially.

For what it may be worth.

73

Mike
W4DSE


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