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Message-ID: <036101c7b19d$8da52260$7900a8c0@athlon1200>
From: "Dave Brown" <tractorb@ihug.co.nz>
To: <rsgb_lf_group@blacksheep.org>
References: <E1I0EIT-00041R-B4@post.thorcom.com>
Date: Mon, 18 Jun 2007 23:41:03 +1200
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Subject: LF: Re: Broad band QRM-500khz
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Status: O

Is the Panasonic system capable of being operated from an external
battery supply? A lot of the modern ones can use a backup battery but
are not designed to operate from an external DC source. But if it CAN
operate from an external DC supply then you could try that-your DC
supply may be a lot cleaner than the mains operated one in the system
itself.
But it may not  be the power supply. Switching garbage (internal
processors etc) could be getting out via the copper extension and
trunk cabling.

This is more of a challenge.  Does the Panasonic system have external
trunks or is it purely an internal system? If you can easily
disconnect all the internal extensions and reconnect one by one,
(listening for noise increase) you may get a better idea of the
coupling mechanism. You need to try disconnecting the trunks as well
if it has any.

The printer supply should probably be replaced with a quiet one-wont
be difficult unless it is providing multiple output voltages.

73
 DaveB.NZ, ZL3FJ


----- Original Message ----- 
From: "Michael Probert" <mjprobert@ynysdawelcottages.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Monday, June 18, 2007 10:17 PM
Subject: LF: Broad band QRM-500khz


> Hello all,
>
>
>
> Many thanks to all who responded to my troubles re the above.
>
>
>
> When my son and colleagues arrived for work ( They run an on line
> retail
> business)  this morning and read the deluge of e mails they shut all
> systems
> down and we turned off the mains power supply. Fed underground.
>
> The phone lines are also fed underground but fixed about 25cms above
> ground
> for about 25m to the input socket.
>
> Using the main transmit antenna, 14mm top loaded vertical, and using
> a
> battery operated receiver the noise had disappeared completely.
> GI4DPE's
> beacon was S7. Only just detected it previously.
>
>
>
> I thought  we had been through this procedure before but with old
> age and
> failing memory I now recall this was done in relation to 80 m noise
> some
> time ago.
>
> Switching power back on we then went through the laborious process
> of
> shutting down the large amount of equipment-Server and network
> systems and
> numerous PC terminals printers etc.
>
> 2 devices are causing the problem.
>
>
>
> Firstly-fairly minor, a power supply to an HP 750 printer. Produces
> a
> carrier across the band.
>
>
>
> Secondly-- an internal telephone system. 20 line - 4 in use,
> Panasonic KXT
> 61610BE-" Electronic Modular Switching System"
>
> The reason I associated the interference with broad band adsl was
> that using
> a portable RX placed anywhere near the telephone line produced
> massive QRN,
> even to the extent that I could detect it under ground.
>
> I can only conclude that somehow this wonderful Electronic Modular
> Switching
> System is feeding back down the phone lines. I am not knowledgeable
> enough
> to know if this is possible but it certainly seems the case.
>
>
>
> I am greatly indebted  to all who offered solutions and secured the
> co
> operation of " workers" this end.
>
>
>
> I just hope some other gremlin does not appear again
>
>
>
> 73s
>
>
>
> Mike   GW4HXO.
>
>
>
> PS Anyone know of an internal phone system -QRM free ? or a possible
> filter
> solution ?
>
>


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