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re: Do I need to look for a UHF AMP for AO-40 ?

How much power you need will depend on how much work you want to put into
your antenna system.  I've only made a few contacts so far and they've 
all been fairly low power.  Mostly, it's been 10W into a pair of homebrew
4' long circularly polared quagi, although the first contact was about 30W 
into just one of them (7 element-pairs).  Don't forget the -3dB correction
if your AO-40 antenna is linearly polarized rather than right-hand circular
powlarization.  If that's not the case, then i would guess you could hear
yourself, but not well and some improvements should be considered.

As many people have said before, and i'm still working on improving, it
is really the receive side that can make the biggest difference.  Sure, 
one can hear the beacon and a decent number of stations with a 18" offset
dish, an AIDC down-converter and an W0LMD patch feed.  But what you won't
hear them well and what you may be hearing much of the time is people
running a fair amount of power.  And you'll be tempted to run too much 
power just to hear yourself.  I found i needed at least a mesh-covered 
BBQ dish to hear myself adequately, or to hear clearly the stations that 
really were 10dB below the main beacon.

You can use a fancy transmitter, or you can use a good antenna; take your
pick.  Or better yet, both; and run QRP whenever the squint is decent.

			       -- KD6PAG
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