> The problem in the Heath SB-1000 switch arcing IMO
> is due to the layout and the Tesla effect. If the 80-160 meter tank coil
> had been wound on a torroid, the problem would have been solved. Just too
> much coil in too little space. As the inadequate padder door knobs change
> value due to heat, the problem will raise its ugly head by burning out the
> band switch. The addition of the washer on the switch contact is not
> enough to overcome the inevitable when values start to change in the
> padders. Ameritron has solved this problem by using robust mica caps as
> padders, which fit nicely into the SB-1000.
>
> IMO, the Tesla effect is the culprit in arcing switches.
The SB1000 had about 50 times the switch failures (as determined
by parts shipped to customers) of the nearly identical AL80A.
The reasons were:
1.) A looser spec on the transformer no-load to full-load voltage
change.
2.) No buck-boost winding to adjust power line voltage.
3.) No anti-corona washer at an area in the switch where voltage
gradient is a problem.
4.) No control over assembly and wiring, including relay contact
adjustments.
73, Tom W8JI
w8ji@contesting.com
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