Garey,
I've been messing around with various metal sheets but I really need to get
a better bond on the chassis. Taking another look at the AC transformer
wiring, it appears that if the transformer is rotated in the right
direction, the lead lengths will all work fine and won't need extending.
However, it will require the drilling of additional chassis holes and I'll
need to dig out my OM's old set of Greenlee chassis punches which love
aluminum but hate steel! Also, the crystal calibrator must be re-located.
I've been using tapped right-angle aluminum brackets for my SM0VPO audio
boards and these will work nicely with the calibrator since the cal board
already has mounting holes that are presently used with Nylon stand-offs.
The calibrator will then be mounted on one end.and also out of the way of
the transformer flux field just to be on the safe side. By changing the
mounting orientation, I also do not want to move the flux problem elsewhere.
In looking at the layout, I see nothing that should be of concern -- but I
won't know 'till it's tried.
I plan on ordering Mu-metal sheeting in the event additional PTO shielding
is needed, but I'm confident that just rotating the transformer will lick
the problem. The current orientation between PTO and the R-4Cs power
transformer could not have been worse. Moving the PTO laterally just one
inch in either direction substantially reduces PTO modulation by the
transformer flux. But, the PTO has to remain where it us due to all the
dial mechanics.
Paul, W9AC
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