[Amps] Alpha 9500 vs. Acom 2000A questions

[Val]

Dick,

As you know, I am biased. I have to admit also that I have never 
touched Alpha 9500. My comments are based on its Manual only.

You are right, the optional fan have to be installed on ACOM 2000A if 
going to be used for serious RTTY contesting or other continuous modes 
transmissions longer than 15 minutes. The external fan price and noise 
are saved to the CW/SSB and casual RTTY users.

The internal fuses are not uncommon. Most of the ham gear, PC hardware 
and house appliances have fuses installed in the cabinet that are not 
supposed to be replaced by the customer. ACOM 2000A main fuses are 
located on the rear panel. The internal fuses protect the HV 
transformer Step Start circuit, the Measuring transformer and the LV 
transformer. It is supposed that if any of those fuses has been blown, 
there is a failure that anyway will reqiure top cover removing.

ACOM 2000A has no LEDs, but the TFT display brightness can be reduced 
as much as you want. Furthermore, ACOM 2000A great advantage is the 
control via a Remote Control Unit only. The RCU is small enough to be 
placed where will not irritate your eyes. In the same time the 
amplifier can be placed everywhere in the shack or in another room, 
basement, attic.

As regards the auto-tune, I do not know how the Alpha does this, but 
it seems the choosen way is not quite effective. The manual says that 
auto-tune will work only if SWR is below 2:1. By the way, the same is 
stated in OM Power's manual. ACOM 2000A limit is way, way  too high. I 
even don't know what is the limit, but had seen how tunes perfectly to 
a wrong antenna (20m beam on 80 meters) showing SWR more than 10:1. 
Whether this is usabel is another question, this only shows the 
amplifier tuning capabilities.

The Alpha manual says  "For SWR more than 2:1, full power (1500W) may 
not be possible", while  ACOM 2000A specification guarantees 1500W at 
SWR up to 3:1 (2:1 on 160m only). Actually this shows what are the 
parts used in the output tank. Obviously the Alpha parts are rated for 
less RF voltage and/or current.

73, Val LZ1VB



> Hi Guys,
>
> I plan to purchase a tube-type Auto-tune amp and am most  interested 
> in an
> Alpha 9500 or an Acom 2000A.  I'd prefer  solid-state, but I want a 
> 1.5kw
> continuous duty rating at a reasonable price so  that rules out 
> solid-state
> amps for the time being.  ($10,500 is too  expensive)
>
> I have several questions before  making the decision and  your 
> thoughts
> would be greatly appreciated.  Before I proceed with the  questions, 
> I'd like
> to share that I'm a serious CW & RTTY contester and am  looking for
> reliability and stability at 1.5kw output all weekend long.   Also, 
> if I purchase the
> Acom 2000A I'll be sure to add the Optional Fan as  I've heard they
> overheat on heavy RTTY usage without one.
>
> Here's my questions:
>
> 1) Several hams report the 9500 isn't always reliable at  selecting 
> the
> correct antenna during band changes.  Has that  issue been resolved?
>
> 2) 2000A, when the transformer is removed, there are 3 small  fuses 
> located
> on the center wall and near the  bottom chassis.  Two of them are 
> 2-amp
> fuses and the other is a 100  ma. fuse.  Those fuses will be 
> impossible to see,
> test, or replace without  removing the top cover and transformer. 
> (major
> time killer to remove  the transformer during a contest)  Have you 
> ever had
> any of those 3  fuses blow?
>
> 3) Will both amps hold up about the same with heavy use and in a 
> salt  air
> environment?
>
> 4) Both manuals say the "brightness of the LED displays can be 
> turned
> down".  I have extreme eye sensitivity to bright flashing  lights, 
> can the LED
> display level be turned way down so the lights are  barely visable 
> on both
> amps?
>
> 5) Which amp is easier to get serviced these days?  Are repair 
> costs about
> the same?
>
> 6) Are the auto-tune features on  these amps reliable?
>
> If you prefer, you can send your comments to me off-list at:
> _K9OM at arrl.net_ (mailto:K9OM at arrl.net)
>
> Thank You & 73,
>
> Dick- K9OM
>
>
>
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