[Collins] 30S1 input connections for 220V

[Dr. Gerald N. Johnson]

Might not hurt, it treats the plate tranformer primary as center tapped, 
rather than 220 floating, I doubt it has much effect on the magnetic 
field. If the power line voltage wasn't quite balanced it might work the 
transformer primary harder trying to force balanced voltages and so 
increase the magnetic field from the transformer. I think if the side 
panel of the power supply isn't vibrating that ground connection added 
in the ASAB and later manual is of no benefit, and might not be a 
benefit if the side panel is vibrating.

I see other problems. In the Yellow Book 30S-1 schematic (1959) it 
doesn't bother to keep track of hot or neutral on the 120 volt 
connection so its possible to have the main power switch in the neutral 
which means with that switch or the adjacent fuse open, the circuits 
still have voltage to ground which is a less safe condition for working 
on the equipment and for keeping line voltage stresses on insulation 
including putting transient voltages on that wiring with the power off. 
Even in the latest on line manual, one half the plate transformer 
primary switched by the main relay is that way because of the necessary 
transformer phasing for the SSB/CW primary tap switching. Also harder on 
the transformer over time and some one servicing thinking relay off, 
there's no voltage on this wiring, but because it broke the neutral on 
the lower transformer winding, not the hot, there IS line voltage there 
all the time its plugged in. There's no simple way to cure that.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 1/23/2011 8:18 PM, John Hensley wrote:
>
> There is an 8th ed. (64) and a 12th ed. (76) PDF for the 30S1 on the CCA site.  The 64 version shows hooking up 220V is donedifferently than in the 76 version.
> Browsing through the service bulletins,  ASAB1015 describes thelater hookup method was devised to reduce vibration excitation to thecabinet sides.
> Am I right in assuming ALL 30S1's should be wired for 220V usingthe 12th ed (76) description?
> John 		 	   		
>