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Re: LF: Re: Mains QRM blanker by PA0LQ

from [Dick Rollema] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: Re: Mains QRM blanker by PA0LQ
From: "Dick Rollema" <[email protected]>
Date: Wed, 01 May 2002 11:51:54 +0200
In-reply-to: <001f01c1f0e7$69ade440$d49601d5@dave>
References: <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
To All from PA0SE

Dave, G3YMC wrote:


The noise canceller which Steve GW4ALG designed is derived from Harry PA0LQ's version
with ideas from other sources - this can be found in the RSGB Low Frequency
Experimenter's Handbook and on Steve's site
(http://www.alg.demon.co.uk/radio/136/intro.htm).
Steve's unit does exactly the same as Harry's - picks up the offending mains
interference with a seperate small antenna and nulls it from the wanted signals.

PA0LQ's noise blanker derives the blanking signal from the mains. It is different from the system described in the LF Handbook.

In my announcement on the reflector I said that PA0LQ used the blanker to eliminate interference from fluorescent tubes. But that is not the case. My aging memory failed me, for which I apologize.
But the blanker is very effective on noise from light dimmers and other pulse shaped interference with mains frequency. When driven by  pulses from a separate receiver tuned to 100 kHz the blanker could possibly also be used to fight LORAN interference, but this has not been tried by PA0LQ.

The description and circuit diagram of PA0LQ's noise blanker and non-ringing 30 Hz wide audio filter are now available in English. I will send it to you by direct e-mail when requested. 

73, Dick, PA0SE
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