I endorse Jim's comments.
All other things being equal, the quality of power amplifiers, whether for
rf or audio can to a large degree be related to their size and weight. The
same argument goes for automobiles: for the same build quality the large
capacity engine under run will give smoother trips and longer time between
overhauls.
A small amp pushing the limits of its linearity will cause more TVI and side
splatter than a larger one putting out the same power, again assuming
similar operating modes.
One reason for the continuing interest in homebrewing power amps is the fact
that home builders can overdesign using surplus parts in a way that would be
uneconomic for a manufacturer.
If you work out how long you are likely to use the new amp, the additional
annual cost of a big amp will be trivial on an annual basis, may even be
cheaper if the lighter amp eats tubes faster.
73 es gl
end
Barry Kirkwood PhD ZL1DD
Signal Hill
66 Cory Road
Palm Beach
Waiheke Island 1240
NEW ZEALAND
www.waiheke.co.nz/signal.htm
----- Original Message -----
From: J. Bradshaw <ac6tk@cybertime.net>
To: <amps@contesting.com>
Sent: Tuesday, 09 January, 2001 9:41 AM
Subject: Re: [AMPS] Advice about what linear to buy
>
> I don't have personal experience of the amps you described, but
> one of the great myths in radio, is that high power amps cause
> substantially more TVI than smaller amps.
>
> The reality is, that if you have a TVI problem at 2000 watts, you
> probably still have a problem at 200 watts and may even still have
> a problem at 20 watts. In fact, I just recently resolved a problem
> that was evident with as little as 40 watts! The actual difference
> between 500 watts and 2000 watts is 6 db and there is greater
> difference than that between various filters and Television
> receiver performance. All transmitters and amps (except some
> government installations) in the US must adhere to certain levels
> of cleanliness, but all transmitters are imperfect to an extent.
> What is most important is that all equipment in the specific RF
> environment be compatible, or be made compatible. Each
> situation has its own set of causes and cures.
>
> TVI is a problem that has to be addressed before you buy the
> amp, as a situation can definitely be made worse. You will have
> to get technical or keeping your own station clean will be a
> matter of luck, although you will have substantially better luck
> staying on 160-40 meters. Commercial operators may be very
> good operators, but RF is still RF and they sometimes have to
> hire people to maintain their stations or take appropriate measures,
> or find someone who doesn't value their skills.
>
> Jim,
> ac6tk
> http://surevideo.go.to
>
> ----- Original Message -----
> From: "Nilsson & Partners AB" <oes@npartners.se>
> To: <amps@contesting.com>
> Sent: Monday, January 08, 2001 11:36
> Subject: [AMPS] Advice about what linear to buy
>
>
>
> Hello out there!
> I am considering buying another amplifier.
> Today I use an old Seltron ( a swedish copy of Collins L1).
> I almost ever use i as I use to manage with 100 W.
> However, now I have taken up Top Band. As most of us have
> limited antennas on this band, you really need to (to some extent)
> compensate this with more power.
>
> My main interest in Ham Radio is DX-ing on all bands and modes,
> Island chasing, contests and now and then also rag-shews.
> When trying to work new countris (today 318) I prefer CW, but of
> course also work a lot of SSB.
>
> As most of us I have limited money to spend so I will never go for
> a very big amp, which probably also will cause TVI.
>
> I am looking for an amp with 500 - 1000 watts. If it is equipped
> with full break-in / QSK, it is a very big advantage to me.
>
> I do not know much about linears but have been told that a used one of
> the models mentioned below can be a good choise:
>
> Icom IC-2KL
> Kenwood TL-922 / 922A
> Yeasu FL2100Z
> Drake L7
>
> The only one that possibly has QSK is IC-2KL, but I am not sure.
>
> I will very much appriciate any advice and/or information from you
> about your opinions and experiences with the above linears.
>
> My station is rather "ordinary" for a DX-er station with an ICOM 765 as
> well as an ICOM 706 MKII together with antenna tuner, paddles and other
> things you
> usually find in a shack. On my 60 feet Versatower is one Mosley Classic 33
> (3 el. tribander), a 3 el six meter Yagi and finally a D3W rotable
> dipole for the WARC-bands. A month ago I put up L-verticals for 80 and
> 160 meter. On 40 meter I use a dipole about 12 meters over the ground.
>
> Many thanks in advance and Best 73 de
>
> Ken / SM7CQY in southern Sweden.
>
> PS Forgot to tell you that I am a rather untechnical person but hopefully
> a better operator. DS
>
>
>
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>
>
>
>
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>
>
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