PDA

View Full Version : Shielded Earth Lead


Jimbo
19-03-2016, 08:33
I am looking for some shielded earth leads for my SUT.

Anyone got any recommendations?
Firebottle
19-03-2016, 16:12
James you don't need shielded earth leads. The lead itself will be at earth potential so shielding from any noise is not required.

Just use a standard piece of multi strand wire, 7/0.2 or 16/0.2.

:)
Jimbo
19-03-2016, 17:02
James you don't need shielded earth leads. The lead itself will be at earth potential so shielding from any noise is not required.

Just use a standard piece of multi strand wire, 7/0.2 or 16/0.2.

:)

Thanks Alan, it was just that I was moving the earth lead around to get a good position and as soon as it went near the amp it picked up hum, moving it away reduced it.

This made me wonder if it was the earth lead that was introducing hum into the SUT and if so would a shielded earth lead solve the problem.:scratch:
Barry
19-03-2016, 17:48
Sounds like you have an earth loop and a poorly shielded mains transformer in the amplifier.
Jimbo
19-03-2016, 18:03
Sounds like you have an earth loop and a poorly shielded mains transformer in the amplifier.

Thanks Barry, think your right there is no shielding of the transformer in the Croft.

How do I shield the transformer?
Barry
19-03-2016, 18:11
Thanks Barry, think your right there is no shielding of the transformer in the Croft.

How do I shield the transformer?

If the casework of the Croft is steel, the transformer will be shielded. I'm not familiar with Croft designs, so I'll have to defer to others on this.
Jimbo
19-03-2016, 18:43
If the casework of the Croft is steel, the transformer will be shielded. I'm not familiar with Croft designs, so I'll have to defer to others on this.

Casework is thin steel but when I move the earth lead close to the preamp it causes hum in the SUT?
rubber duck
19-03-2016, 19:05
I have a similar problem with my 25 but not my 25 Basic. I've minimised hum by moving the preamp away from t/t.