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Re: Class A, AB1, B, C Operation/Modes [message #96455 is a reply to message #96450]

Wed, 01 March 2023 19:45

gofar99
Messages: 1905
Registered: May 2010
Location: Southern Arizona

Illuminati (5th Degree)

Hi, Indeed. The way I get around this in all my gear, both commercial and diy is to isolate the signal ground from the chassis. I always use the third wire (AC mains ground) and attach it securely to the chassis. The internal circuitry ground is connected to the chassis via a type X2 capacitor and parallel resistor. (some folks prefer a diode bridge) There can be no other connections between the two grounds. This is important. Beware of chassis mounted jacks as they can defeat the protection. What this does is prevent ground loops through the AC mains but allows the chassis to still protect the users. A side benefit is the chassis still can act as an EMI shield for the internal components. This arrangement complies with electrical standards and makes for a quiet piece of gear no matter what it is connected to. Any faults in the circuitry are either handled by the fuse (an absolute necessity) or at least kept from harming the user. The typical component values are between 0.1 and 0.2uf and 100-150 ohms 1-2 watt size is usually fine. The capacitor needs to be AC mains rated thus the X2 designation. Usually the voltage ratings are 275 or 350 VAC. There are a few less common AC mains rated caps but the X2s are easy to source and not costly. Even though many companies used other common types in the past they are not recommended as they are not self healing and can short through. Good discussion.

Good Listening
Bruce

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[Message index]

		Class A, AB1, B, C Operation/Modes By: positron on Sun, 05 February 2023 20:40
		Re: Class A, AB1, B, C Operation/Modes By: Wayne Parham on Sun, 05 February 2023 20:54
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Mon, 06 February 2023 20:38
		Re: Class A, AB1, B, C Operation/Modes By: positron on Tue, 07 February 2023 16:13
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Tue, 07 February 2023 19:33
		Re: Class A, AB1, B, C Operation/Modes By: positron on Tue, 07 February 2023 20:37
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Thu, 09 February 2023 21:01
		Re: Class A, AB1, B, C Operation/Modes By: positron on Thu, 09 February 2023 21:35
		Re: Class A, AB1, B, C Operation/Modes By: positron on Tue, 28 February 2023 19:04
		Re: Class A, AB1, B, C Operation/Modes By: Wayne Parham on Wed, 01 March 2023 08:28
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Wed, 01 March 2023 19:45
		Re: Class A, AB1, B, C Operation/Modes By: positron on Sun, 05 March 2023 00:33
		Re: Class A, AB1, B, C Operation/Modes By: Wayne Parham on Sun, 05 March 2023 08:05
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Sun, 05 March 2023 08:10
		Re: Class A, AB1, B, C Operation/Modes By: positron on Mon, 06 March 2023 19:01
		Re: Class A, AB1, B, C Operation/Modes By: positron on Sat, 06 May 2023 22:32
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Tue, 09 May 2023 21:30
		Re: Class A, AB1, B, C Operation/Modes By: positron on Thu, 11 May 2023 00:26
		Re: Class A, AB1, B, C Operation/Modes By: positron on Tue, 05 September 2023 23:48
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Fri, 08 September 2023 21:12
		Re: Class A, AB1, B, C Operation/Modes By: BreakneckRedneck on Sun, 24 September 2023 00:42
		Re: Class A, AB1, B, C Operation/Modes By: positron on Thu, 12 October 2023 11:21
		Re: Class A, AB1, B, C Operation/Modes By: positron on Fri, 03 November 2023 12:22
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Fri, 03 November 2023 20:58
		Re: Class A, AB1, B, C Operation/Modes By: positron on Sun, 05 November 2023 01:38
		Re: Class A, AB1, B, C Operation/Modes By: positron on Thu, 07 December 2023 23:12
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Mon, 18 December 2023 20:20
		Re: Class A, AB1, B, C Operation/Modes By: positron on Tue, 16 January 2024 21:32
		Re: Class A, AB1, B, C Operation/Modes By: gofar99 on Wed, 24 January 2024 20:31

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