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[Amps] Alpha 87A amp

To: <amps@contesting.com>
Subject: [Amps] Alpha 87A amp
From: w9ac@arrl.net (Paul Christensen)
Date: Wed, 16 Oct 2002 11:14:15 -0400
Of course, Alpha's main competitor in this performance and price class is the 
ACOM 2000A.  I have owned two ACOMs and two 87As.  I
now run only the older battleship Alphas.  Anyway...

Both the 87A and ACOM performed well.  At the time, ACOM had not yet released 
their control software and promises were left empty
for a long time.  I believe they've addressed this, however.  The 87A control 
software worked flawlessly.

>From an operational perspective, I actually enjoyed using the 87A over the 
>ACOM.  High speed CW with a high power PIN diode is tough
to beat, but then its less forgiving to high VSWR than the ACOM's Kilovac KC-1 
vacuum relay.  The ACOM was plenty fast and on my
monitor scope, it never hot switched and the in/out sequencing was fine even at 
45+ WPM.

It's a close call., but I thought the overall construction of the 87A was 
superior to that of the ACOM.  In one particular
area....the motor servos, the ACOM uses a really scary Russian type.  If you 
look at the servo, I swear it was machined by hand in a
vise in someone's basement....very, very rough.  However, they seemed to 
perform fine.  Nevertheless, the look of the Russian servos
scared the Hell out of me in the event the part no longer remained available or 
ACOM no longer supported the amp.  On the other
hand, if it's a common servo configuration both mechanically and 
electrical....maybe it's not a concern.

In both ACOMs, I lost the 3-state electronic bias switch.  Same part....a 
TO-220 switching transistor as I recall.  Even though the
amps did not come with a schematic (early 1999), I was able to repair it myself 
based on a couple e-mail exchanges with Vasko.  I
didn't detect any other problems in the two years I had the ACOMs.  The only 
problem I had with one 87A was that the input
bandswitch was not completely aligned and keyed properly.  As the amp would 
automatically switch from band-to-band input VSWR would
sometimes indicate considerably higher, but the fix was easy enough.

The ACOM uses tubes that are less expensive than in the 87A.  The 87A is a GG 
design.  The ACOM uses tetrodes and the measured IMD
performance of the 87A is significantly better than the ACOM 2000A (caveat: 
this data was measured by the ARRL labs on one set of
amps.  Another set of amps may have yielded different IMD figures).

The ACOM's autotuning feature works differently than Alpha's.  You find the 
optimum tuning and loading point within any band segment
just once and forget it.  If the antenna loading changes, the ACOM WILL NOT 
compensate.  The 87A's ALPHAMAX will compensate for load
changes, but it does not have a precise, one-time auto tune/load function.  
Yes, it is capable of full autotune, but it's not as
precise as the ACOM.  The 87A is best adjusted manually for a given band 
segment and then saved in memory.  Then, I would engage
ALPHAMAX to take care of the rest.  The bottom line is that if you have 
antennas that are subject to loading variances, the 87A does
the tuning best.  If you can count on the antenna's VSWR to remain absolutely 
constant, the ACOM does a better job.

Just my opinion....and worth just what you paid for it...

-Paul, W9AC

----- Original Message -----
From: "Bob Otto N8NGA" <N8NGA@one.net>
To: <amps@contesting.com>
Sent: Wednesday, October 16, 2002 10:38 AM
Subject: [Amps] Alpha 87A amp


Forgive me if this is a subject covered......I'm new to the list.

I'm considering purchasing a Alpha 87A amp 1Q03.  The price has increased 
substantially since the new ownership.  Does anyone have
experience with the amp under the new ownership?  Are there better alternatives 
to the Alpha?


73 from....
Bob Otto
,,,,,,,
Ô¿Ô¬
Cincinnati, Ohio
Scottsdale, Arizona
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Wednesday
10/16/2002
10:35:05 AM

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~Sam Snead



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