Message-ID: <007401c90901$59ceeb80$0301a8c0@mal769a60aa920>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <006501c908f3$c99610a0$0301a8c0@mal769a60aa920> <38977.212.137.53.1.1219919382.squirrel@sighthound.demon.co.uk>
Date: Thu, 28 Aug 2008 12:29:35 +0100
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Subject: Re: LF: 531khz etc
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I can work through the loran on 137 and rte on 500 with narrow cw filters 
for my preferred mode but I have seen lots of comments in the past about 
this qrm and was just wondering why those most effected have not complained 
as far  as I know, maybe you know different.
My DX qso's are fast and brief usually,  but under favourable propagation 
condx I could be persuaded to prolong a qso!!
Rag chew qso's could be a problem with the above mentioned qrm.
Since you are now in full swing chasing faulty transmitters and know the 
procedures have a bash at sorting out loran and rte, there is no point in 
anyone else re inventing the wheel. GO FOR IT John.
I heard you on 500 a while back, but not lately, good signal.
G3KEV

----- Original Message ----- 
From: "John P-G GM4SLV" <gm4slv@sighthound.demon.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, August 28, 2008 11:29 AM
Subject: Re: LF: 531khz etc


Mal wrote:

> I wonder if the fault has been rectified just as a matter of interest

It is much better, thanks for asking. Occupied bandwidth now 4.8kHz, with
clearly defined cut-off due to appropriate baseband filtering. Modulation
depth is now only 40% though, which means it's a bit quiet, but no severe
carrier cut-off on peaks of negative mod, so no severe splatter over
adjacent channels at least.

There is still some evidence of wider spaced noise-like artifacts, much,
much reduced in amplitude from what they were, in the 500kHz band, so it's
a step in the right direction, but more work needed. I've communicated
this to the commissioning engineer, along with supporting spectrum plots
etc. This new TX is a 50kW Thomson TMW2050, and will be moved soon to a
new building and become a standby TX. Another new 100kW TX is to be
installed as the main TX. All the modulation problems and spurii should be
cleared up as part of the final commissioning, later this year.

> it is not causing me a problem in this area

That's good, for you. Hopefully by reporting this to the broadcaster, and
through liaison with the commissioning engineer from the manufacturer I've
helped others who may have had problems, it certainly improved the band
for me. It has also helped the broadcaster, before falling foul of the
ITU, as they were well out of spec.

> however I wonder why there is not the same enthusiasm to clear up the
> RTE harmonic on the 500 khz band and also the Loran spread across the
> 137 khz band.


Well, if you perceive it to be a problem, then ask yourself why you,
personally, haven't done anything about it?

Why wait for someone else to do the hard work?

If you think RTE's 2nd harmonic is outside ITU specification, and is
causing undue interference, then by providing suitable supporting
evidence, measurements etc. it should be an open and shut case. Contact
the broadcaster or regulatory body and state your case.

Go on, put yourself out for the good of the community, instead of sitting
there moaning that the rest of us are all feckless appliance operators.
Take a break from working DX on top-band and use your RF skills to help
the amateur community.

John GM4SLV




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