From: G0MRF@aol.com
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Date: Wed, 12 Apr 2000 19:55:01 EDT
Subject: Re: LF: (More) Nonsense from Kev
To: rsgb_lf_group@blacksheep.org
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In a message dated 4/12/00 10:16:44 PM GMT Daylight Time, 
g3kev@netscapeonline.co.uk writes:

<< Very few signals generated by such amplifiers and used by radio amateurs 
have
 a pure sine wave output after one 5 pole LPF, except at very low power
 levels,  >>

Hello. 

I think you will find that the relative level of harmonics (dBc) will depend 
on the characteristics of the LPF and source / load impedances i.e. the 
correct filter terminating impedance, and not the applied power levels.


Equally:  The relative level of radiated harmonics (dBc) is generally 
speaking independent of antenna whether it's at 130 feet or a long wire a 
"few feet off the ground"

"amateurs....push class D/E amplifier too hard"  - With square wave drive the 
harder they are driven, the better they are. 
 
No one has a pure sinewave output.

A low pass filter will not remove key clicks as they are within the passband 
of the LPF.

90% of multikilowatt MF broadcasters use class D/E etc.

Surprisingly, the UK amateur radio licence allows up to 1% of energy to fall 
outside the amateur bands, so this would not be of any interest to the RIS. 
In anycase 250Hz is 'inband' and would be considered a problem to be resolved 
by the band's users. - If it was considered a problem at all.

Using a computer and spectran / gram clearly demonstrates the larger 
bandwidth occupied by fast CW transmissions. As the band is very narrow, 
should we put an upper speed limit on CW  - to limit the occupied bandwidth? 
(Hi)

Goodness Mal.   They only had a mast bigger than yours.

"So many negative vibes" - Donald Sutherland.

73

David