Message-ID: <00fa01c30323$ccc66a80$3704210a@Hugh>
From: "Hugh M0WYE" <m0wye@thersgb.net>
To: rsgb_lf_group@blacksheep.org
Date: Tue, 15 Apr 2003 08:51:04 +0100
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Subject: LF: Re: The Mystery of The Missing Amps
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Hi Ian, et al,
First can I say how much I enjoy reading Ian's postings - they are always a
good read and highly entertaining !

Second. When I started messing about on LF, I was using a TDA2030 Amplifier,
and then graduated to a BK amp. I tested the TDA amp using a Loudspeaker at
audio frequencies, and at one point I connected up the LF aerial/earth
without removing the speaker - I nearly jumped out of my skin as a huge hum
came from the loudspeaker. The Amp was grounded both through the signal
generator driving the input AND the RF ground, and that made a huge hum
loop.

So now I transformer-couple the input to the amplifiers, using a little
transformer wound on a toroid out of the junk box. This breaks the earth
connection at the input, so the only earth is the network of ground stakes
in the garden.

The Mains earth on the BK is just connected to the metal chassis, and the
Audio Earth is completely floating - so it is just the earthing arrangements
on the input to the Amp that you need to examine.

Anyway, glad to hear you've got your current up Ian. I'm afraid my loading
coil has been moved to the garage, while the garden is spruced up, for the
spring.

73
Hugh M0WYE