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@arrl.net_ (mailto:K9OM@arrl.net)
Thank You & 73,
Dick- K9OM
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