Date: Sat, 15 Apr 2017 19:49:46 -0400
From: "Carl" <km1h@jeremy.qozzy.com>
To: <donroden@hiwaay.net>, <amps@contesting.com>
Subject: Re: [Amps] Mobile Amps ?
Amplifier use is not limited to the USA and 1500W is far from a world
standard.
Carl
## In some of the former soviet countries, power limit is determined by how
much you pay for the license. If you are willing to pay more money, you
are allowed to run more power....and the license reflects that info. This is
not bs
either. If you have the $$, like some club stations do, the legal power levels
are through the roof.
## Some countries outside the usa measure the power at the ant, across
an Z matched load. Or forward watts minus reverse watts. UK vhf
+ uhf ops do this.
## In canada, its 750w output on cw... measured at the ant. And
2250 watts pep out on ssb, at the ant. 750W out on rtty and FM, and
data modes..at the ant. 750w CXR on AM..measured at the ant. Pep out on AM
can easily be 4-6 times cxr, depending on amount of positive modulation used, so
3 to 4.5 kw pep out on AM...measured at the ant. And your rinky dink 8877
will need to put out 2.5 kw pep out.... just to get 2250 pep at the ant..with
just
a half a db of feed line and connector loss..which is why I dont use a 8877.
Now if you want to be a good neighbour, with superb IMD, and run class A,
then the eff goes to hell..and you need an even bigger tube.
## Its all rather silly anyway. 5 kw into a low dipole is a no-no..... but
1.5 kw
into a massive stacked array on 20M..with an ERP of 150 kw is... just
hunky dory.
## If you have 2 x 20m yagis..and each one is pointed in a different
direction,
like say EU and VK, you just lost 3 db due to the power splitting. Fix is..
run legal limit into the feedpoint of each yagi..which is what a lot of folks do
already. Contesters in EU will use a separate amp for each coax, but that is
real old news. OH2BH was doing that back in the 90s... on the rear cover of
CQ rag...in an alpha amplifier full page, high gloss advertisement. One
FT-1000 D drives a pair of identical aplha linears..then one 20M coax to
each amp. 2 x 20m stacked yagis. Old news.
Jim VE7RF
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