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Re: LF: Selection of spot frequencies for DX

To: [email protected]
Subject: Re: LF: Selection of spot frequencies for DX
From: "Vernall" <[email protected]>
Date: Thu, 27 Mar 2003 07:06:55 +1200
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
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

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