Actual need for ground was Re: [Johnson] Fused Plugs

Sat, 08 Mar 2003 17:10:55 -0500

Gents,

This is a fairly straightforward safety issue. Here's how it goes; Johnson and most other gear have smallish capacitors from both sides of the power line to the chassis. This is intended to help filter RF noise from the power line. These capacitors don't need to "fail" to cause serious damage to boat anchor lovers, they just need to leak! Can you imagine a leaky 40 year old capacitor!

All it takes is sufficient leakage to allow tens of ma. to flow to the chassis and then through you to a better ground. Under normal conditions, if you have the ground post connected to a good ground that is close to your power ground, and/or your coax connector shield ends up at a good ground because your receiver is grounded, all will be fine.

The problem comes up when the ground wire falls off (you do have one I hope!) and you disconnect coax cables, perhaps at the receiver. Your left hand has the shield of the coax going toward the antenna relay at the Johnson (two-wire power cord), your right hand has the coax shield going towards the receiver (three-wire power cord or good ground) now the leakage current completes through the
hand-heart-hand path. This is not a good situation if you want to outlive the boatanchors!

Yes, I've done it too, and I'm still here, but by using grounded power cords (there's one in my Viking 2) the problem goes away. I can't see that it detracts from the interest in a boatanchor, and can make ownership much less painful.

73, Joel Hallas, W1ZR

kwylow zinjanthropus wrote:

> O.k. Just wanted to know: has anyone actually experienced a failure of their Johnson rigs that would have warranted that third ground connector for protection? I'd like to know. If anything (if I were to "retrofit" my Ranger without doing the entire changeover) would be to add a groundwire to the chassis and hook it up externally to the third connection on a powerstrip. Thanks. Cal, N6KYR
>  Robert Nickels <[email protected]> wrote:Not long ago Roy Morgan posted some excellent information designed to keep
> us from prematurely joining the ranks of Silent Keys by relying on the fused
> plugs commonly used on Johnson and Heath gear. Thanks, Roy for explaining
> the potentially lethal safety problems caused by fused plugs, and the need
> to replace them with properly fused 3-wire cords.
>
> A good source of replacement 3-wire power cords are those used by computers
> and periperals, but most of them use the European color designations For
> years, the colors of individual conductors in cords for use in North America
> have been black for line, white for neutral, and green for earth (ground).
> But in order to harmonize worldwide standards, two major UL equipment
> standards, UL 1950, Information Technology Equipment, and UL 2601, Medical
> and Dental Equipment, started several years ago to require the more
> traditional European conductor color coding: brown for line, light blue for
> neutral, and a combination of green and yellow for ground.
>
> The color conversion is as follows:
>
> LINE (US) Black = (EU) Brown
> COMMON (US)White = (EU) Blue
> GROUND (US) Green (EU) Green/Yellow
>
> "Switch to Safety" was a good motto when our boatanchor radios were new, and
> still is today. I replaced the cord on my DX-100 today and urge others to
> do the same. Before rewiring your gear, please check a website like
> http://www.sherline.com/powrcord.htm to make absolutely sure you wire things
> up right, and play it safe!
>
> 73, Bob W9RAN
>
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