Message-ID: <002b01c2f3cb$020221c0$b8e136d2@xtr743187>
From: "Vernall" <vernall@xtra.co.nz>
To: rsgb_lf_group@blacksheep.org
References: <5.1.0.14.0.20030320183946.0260e158@gemini.herts.ac.uk> <5.1.0.14.0.20030324122153.00abb360@gemini.herts.ac.uk> <3E7F197A.4060502@usa.net> <003201c2f247$ee408200$0100007f@xtr743187> <5.1.0.14.0.20030326110918.00abac60@gemini.herts.ac.uk>
Date: Thu, 27 Mar 2003 07:06:55 +1200
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Subject: Re: LF: Selection of spot frequencies for DX
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Jim and others,

Thanks for getting the numbers straightened out.  I've been hasty with email
recently due to "not enough minutes in the day".  The mains harmonic
situation is that "very high" frequency stability would be needed to not
have harmonics sweeping over LF DX working frequencies that were selected
for being "interleaved" with N times 50 Hz.  Also N times 60 Hz for
consideration of North America, etc.  However, I believe these interleaved
spots are still the best from a statistical point of view, as mains
harmonics would be expected to spend most time around the N times 50 and 60
Hz regions.

> >I made a numerical mistake in my last posting.  25 Hz shift at 136 kHz is
> >a ratio of about 0.009, or 0.9%.  Of course, we would like the "QRM
> >deviation" of 50 Hz lines to be much less than plus or minus 25 Hz.
> >
> >73, Bob ZL2CA
> >
> Dear Bob, LF Group,
>
> 25/136000 = 0.00018, or 0.018% for 25Hz shift - a 0.9% shift in the 50Hz
> mains frequency would lead to the 2720th harmonic shifting by 1224Hz...
>
> Cheers, Jim Moritz
> 73 de M0BMU

73, Bob ZL2CA