[1000mp] Linear Amplifier Recommendations for Use with FT1000 Mark V

Mon, 25 Feb 2002 22:04:11 -0500

I know this sounds like heresy to some but I have been successful running
two medium power amps off stiff 120 lines.  I ran dedicated 20 amp circuits
right from the box that are used by Ameritron amps AL 81H and AL572..  The
runs were less than 15 feet (which helps minimize voltage drops that some
might complain about).  I run two amps that new, sell from within your price
range;  The Ameritron AL811H will give you 700 watts CW and 800W+ PEP (as
measured by an RF Applications digital meter).  Power drops to about 550 CW
on 15 meters...  have never bothered to open it up on 10.  BTW...  The 811H
has an adjustable tuned input that never goes above 1.3:1, at least
according to my MP.  Keying and ALC voltages (ALC being unnecessary if you
just limit your drive power) can be done directly through RCA jacks on the
back of the 'MP.

Another amp I use here is the Ameritron AL572B.  It will give you 1000 watts
out on CW and 1300+ PEP on SSB.  It also has tuned inputs and can be keyed
directly from the back of the 'MP.  Right now, I drive it with a TS 870.

I have Kenwood SM-220 scopes to check linearity of each amp and to date have
encountered no problems in that regard.  Ameritron claims that either of
these amps will run just as well on 120 as on 220, as long as the lines are
stiff.

The difference between these lower cost Ameritron amps and the dual 3-500Z
amps and above (in my book anyway) is how long they can keep up their
maximum power output.  The AL572 only has 600 watts of pate dissipation
whereas the dual 3-500Z amps have 1000.  The larger, more expensive amps
have more.  Perhaps more importantly, the power supplies in these heftier
amps are capable of higher power levels for longer periods of time.  Its
during the heavy duty cycle modes (like RTTY) when the 120 line will start
of heat up, drop voltage and reduce power and/or linearity.

If you have just spent a lot of money on an MP but still want an amplifier,
personally, I find nothing wrong or foolish about going with one of the
medium duty/lower price Ameritrons running of 120 volt lines if that is more
convenient for you.  At least in theory,  the difference between 800 watts
and 1500 is < 3db.  I also would like a larger huskier amp.  Who wouldn't.
Like you, I choose not to pay the big bucks right now.

Have fun and enjoy your new MP+ amp.

Bill / K8DXX

Also, regarding tubes, I purchased a matched set of four 572Bs for $200 from
RF Parts.  Just for the heck of it (no extra power, just durability, I
guess), I put them in my AL 811H.  They work fine but never see more than
1700 volts on the plates (rated at much higher voltage and 2X the
dissipation of the 811As).  The carry the old Taylor brand but are made in
China.  RF Parts warrants them for a year, just like the more name brand
tubes.  They claim that MTBF on the Taylor 572Bs is better than Cetrons.  We
all know what problems Svetlana had with

----- Original Message -----
From: "Rick" <[email protected]>
To: <[email protected]>
Sent: Monday, February 25, 2002 8:07 PM
Subject: Re: [1000mp] Linear Amplifier Recommendations for Use with FT1000
Mark V

> I have a 30L1, drive it with my 1000MP, get 600 watts out, except about
400
> on 10m.  Quiet as a churchmouse, hot enough to fry a hamburger on it.
Other
> than the fact it doesn't cover 160 m it meets all of his requirements, and
> you can get them for about $600.  Depreciation is probably non existant.
> My opinion - for 600 watt out amps you don't need 220, its overkill.
> Most of the opinions on this subject may be technically correct but most
> also ignore what the guy SAID he wanted - a medium power amp, under $1200.
> (If he wants a Corolla don't try to sell him a big SUV !!!)
>
> Rick  K2XT
>
> ps - I also have an L4B on a 220 line !
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