This is a discussion that has been going on for a long time with Astron 
supplies, although a few other manufacturers have also been known to tie 
the negative output to chassis ground.  As previously noted, 
repeater-builder.com sites an example with a repeater installation where 
the Astron supply with the negative line strapped to ground caused 60Hz 
hum on the repeater's output due to a ground loop. However, I have also 
read on other sites where the negative line should be strapped to case 
ground, whereas Jim, Tom, and others state firmly otherwise.  Perhaps 
Astron used this "fix," as an easy out for a relatively poorly designed 
regulator circuit??  I'm sure the discussion will continue, as it has 
lasted ever since Astron made the running production change to their 
supplies.
73
Don W9CW
On 9/5/2012 6:30 AM, Mike Hyder -N4NT- wrote:
 Jim, you might want to take that up directly with Astron. I speak only 
from my own experience. You can argue theory but you can't argue my 
experience.
73, Mike N4NT
 ----- Original Message ----- From: "Jim Brown" 
<k9yc@audiosystemsgroup.com>
Cc: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Wednesday, September 05, 2012 01:16
Subject: Re: [TenTec] Station power supply??
 
On 9/4/2012 7:42 PM, Mike Hyder -N4NT- wrote:
 
The  way I grounded the negative lead
 
 
 But the NEGATIVE lead should NOT be bonded to the chassis in the 
power supply. The GREEN WIRE MUST be bonded.
73, Jim K9YC
 
 
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