[Hallicrafters] SR-2000 HUM PROBLEMS |
James Liles
james.liles at comcast.net
Tue May 31 20:13:46 EDT 2011
From: James Liles
Sent: Tuesday, May 31, 2011 7:04 PM
To: W4AWM at aol.com
Subject: SR-2000 HUM PROBLEMS
Hi John and Jim:
Thanks for the response. Probably a poor choice of articulation. I was referencing the wiring within the radio not the incoming service. Maybe this will clear this concept. A three wire plug has a white, black, and green wire where the green wire is attached to the chassis. The white 0v and the black 115v enter the radio and are attached to the transformer and switch both of which have no affinity to the chassis. Both sides of the power input for 115v have no sense of which is 0v or 115v. Reversing the two pin plug in the SR-400A does exactly the same thing. It’s easier to look at the schematic for the SR-2000 or SR-400A to make sense of it. Probably should not have said neutral but referenced the white and black as the input leads plural within the power supply. I’ll correct that and if you still feel that the concept is inappropriate let me know. There are an awful lot of radios out there that use 2 pin plugs and reversing the plug on many will reduce hum. The SR-400A is a good example where most exhibit this phenomenon. Have a good day and thanks for responding in a courteous way. A refreshing concept.
Kindest regards Jim K9AXN
From: W4AWM at aol.com
Sent: Tuesday, May 31, 2011 5:21 PM
To: james.liles at comcast.net ; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] SR-2000 HUM PROBLEMS
Hi Jim,
I don't tout myself to be an expert but as they say, a little knowledge is a dangerous thing. These are just my thoughts and I am not an expert in the National Electrical code, so here goes:
I glean from your message that you are speaking of a rig operation on 125V. If this is so and you switch the neutral, you are essentially switching the ground, too since both neutral and ground wind up in the same but different buss bars in your service entrance box. Even though the rig is grounded, doesn't this arrangement either make the chassis hot of blow a fuse? I realize depending on which way a non polarized plug was inserted on the old AC/DC sets, the chassis could become hot. That is why when a set such as the S-38 is rewired with a 3 wire cord set or has a polarized plug installed, one has to make sure that it is the hot wire that is switched,
I may be totally wrong on this and I'm sure the fires will be lit, but that's the way I see it. I am sure you have done this before and it evidently works, but I'm really curious about it.
One thing I do know is that when installing a service entrance transfer switch, it is against code to switch the neutral.
I bow to your expertise.
73,
John, W4AWM
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