Message-ID: <38F75EFE.FACEC103@netscapeonline.co.uk>
Date: Fri, 14 Apr 2000 18:10:06 +0000
From: "g3kev" <g3kev@netscapeonline.co.uk>
Organization: Netscape Online member
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: (More) Nonsense from Kev
References: <c5.407ddb9.262666d5@aol.com>
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G0MRF@aol.com wrote:

> 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.

On any other amateur band it would be considered a problem if it
interfered with
other amateur transmissions so what is special about 136 khz. It would
certainly
concern me if every cw transmission had a 250 khz spread of key clicks.
Dont
suppose you are a regular cw operator.
I think the RIS would be very interested if there was a complaint.
You misread my original message and getting confused about key clicks
and
harmonics.
Key clicks are one thing and harmonics another.
1.  I was making the point that the transmission had key clicks and
needed to be
checked.

> 2. I was saying that because of the intensity of the signal, the odd harmonics
> also needed to be checked to avoid interference to other services and use
> several poles of LPF'S to avoid harmonic radiation, especially if an erp of 100
> w is to be used.
>
> 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?

You dont have to worry David there is no chance of you exceeding the
speed limit
!!!!!!!!!!


>
> (Hi)
>
> Goodness Mal.   They only had a mast bigger than yours.
The difference is that I bought and installed my own mast !!!!!!!!!!!

"Oswald Mc Donald Jr"-----
Nothing like owning your own MERCEDES instead of borrowing a friends
!!!!!!
>
> "So many negative vibes" - Donald Sutherland.
>
Was Donald able to explain to you why your signals were not getting as
far as Scarborough in spite of all the rhetoric from your qth. 

> 73
>
> David