[Lowfer] Isolation transformer, Computer noise, etc.

[Paul Daulton]

I agree . While I dont have much noise here my neighbor AF5M about 
1mile away as the crow flies has terrible noise. Paul is a DXer and is 
very much bothered by it. Some of the ideas in this thread may help 
him, and possibly improve my rec on lowfer.. 

I wonder what sort of core to use on the HF bands , particularly 160 
meters. I have two Q meters so inductance and reactance measurements 
are no problem. 

Paul K5wms

Quoting "Mike.WE0H" <we0h at gmx.com>:
> Thank you Bill for bring us up to speed on the transformer. I need to
> wind one for my HF vertical as the common mode noise is absolutely nuts
> on it. My 600m vertical is transformer coupled so it is stone quiet. 
>
> Things like this thread are what the email reflectors and Groups are
> good for. We all learn by the replies from everyone. It's like sitting
> in a virtual classroom with a little delay between people talking. hi hi
>
> Mike
> WE0H
>
>
> Wild-Bill wrote:
> > "I'd like to say someone said years ago that you want 4x the feedline
> impedance "for the primary & secondary of the transformer"
> >
> > Correct, Mike, but the 4X relates to the inductive reactance of the primary
> and secondary of that transformer and this value of
>
> reactance is proportional to the frequency of use. The formula is: XL =
> 2 x pi x F x  L    So set up the inducance (L) for the
>
> lowest frequency of use. At higher frequencies the 'X' factor will be
> proportionally larger and this is OK. 
> >
> > One of the advantages of an isolation transformer back at the shack 
> is that it
> prevents most of the powerline hash present
>
> on the house ground system from being sent out to the antenna site. To
> prove out this theory and determine how much the power line noise
>
> is, connect a wire of the same length as the lead-in to the AC ground in
> your house and place the other end near the base of your antenna. 
>
> Listen to a weak signal at a frequency close to where you are operating
> and 'make' and 'break' the connection to AC ground. You should hear
>
> a considerable increase in noise when the wire is connected. 
> >
> > Another way to determine the effectiveness of your isolation 
> transformer is to
> temporarily jumper the return lines on both sides of
>
> the transformer. The noise should also increase by quite a bit. 
> >
> > Bill
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Paul Daulton K5WMS
beacon WMS 185.302 khz qrss30/slow 24/7
Jacksonville,Ar 72076
em34wu