[RFI] RFI from Astron power supply

[Jim P]

Brian,

I compute the effective 'resistance' (X_sub_c) value
to be only around 16 Ohms* for a .01 uF cap for the
band where I notice the noise.

This might be wholly insufficient to quiet this beast
down (we are probably talking low impedances I am
hazarding to guess in the dode 'mechanism' that is
producing this noise phenomonon given the currents
and voltages involved) and the only 'band' I have
noticed it on is the AM broadcast band (as heard
on other receivers in the vicinity when the RS-35M
power supply is on and load current is being drawn).

Jim P  // WB5WPA //


  * X_sub_c = 1 / (2 * pi * F * C )

    where F = 1 MHz and C = .01 uF


----- Original Message ----- 
From: "Brian Goldsmith" <brian.goldsmith at echo1.com.au>
To: "'RFI Reflector'" <rfi at contesting.com>
Sent: Saturday, May 26, 2007 8:51 PM
Subject: Re: [RFI] RFI from Astron power supply


>
>
> -----Original Message-----
> From: Jim P
>
>
>
> I have to say that I have observed RFI coming from my Astron RS-35M
> 'linear' supply. It is in the form of a pulse or 'buzz' at the line rate.
It
> kind of low-level and is noticable on the AM broadcast band; I don't
> usually hear it on the ham bands even when using it to power the
> HR rig doing the receiving.
>
> The supply is not oscillating, but there would appear to be something
> else taking place generating this 'RFI' linked to the line (AC input) side
> of things.
>
>
>
> ****Most probably diode switching noise.A .01 ceramic across each of the
> main rectifier diodes wiil cut this type of noise out!
>
> Brian Goldsmith.
>
>