On Mon, 24 Mar 1997 11:41:20 -0500 (EST), Michael Spencer
<n4xse@amsat.org> wrote:
>I wish I knew why this amp and others from the same company get a bad rap
>in some quarters.
>
>It is true that I have not used one, and maybe this will make the
>difference, but I have been doing a lot of research and this rascal (and
>the 1500) have a lot of satisfied customers out there like you.
>
>Does anyone have anything to add?
--------------------------------------------------
Ok, you've hit my hot button. I have an Ameritron AL-1200 which I
would rate as a fair piece of gear, but with some caveats:
1. When I received it, the safety interlock switch on the top cover
was miswired. With the cover off and power applied, the HV supply
should have generated zero volts. Instead, it generated over 400
volts DC! Nowhere near the full voltage of course, but lethal none
the less. The problem was in the way the transformer primary was
wired. The schematic in the manual was correct, so when I re-wired it
to conform with the schematic, the interlock worked fine. I sent this
information to Ameritron with before and after schematics, but never
heard a word back from them. Some things are too painful to
acknowledge, apparently.
2. The slow-start circuit was very inadequate, in my opinion. The
amount of delay was way too short, only a few milliseconds. As a
result, when the delay relay closed, there was a humongous arc at the
relay contacts. I'm talking an arc hot enough to light the room. I
removed that circuit and installed an Amperite time delay relay in
it's place. Now there's a nice slow, four-second warm-up and the amp
comes on gentle as a kitten. The previous design is inexcusable.
3. After running some full-power RTTY on 160 meters, I smelled
something funny. Upon removing the cover, I noticed the last three or
four turns of the 160 meter coil had melted the plastic rods which
hold them. That end of the coil is right next to the cabinet, so
presumably there was some coupling to the (lossy) steel case. I
removed the melted turns, figuring their loss would only increase the
Q slightly and not really hurt anything. It did tune up ok, but I
never ran RTTY on 160 again. Shortly afterwards, I sent email about
this to the designer who said "Hmmmmm... most people don't run RTTY on
160 meters. I'll look into it." I never heard back from him either.
4. During the last RTTY contest, I had been running stations on 80
for about an hour when there was another room-lighting arc and the
power output dropped to zero. To make a long story short, the 80
meter tank coil had gotten hot enough to melt the solder attaching the
tap, and it let go. In additon, the whole 80/160 meter coil supports
had melted and the coil twisted itself into a replica of a slinky toy.
In spite of it's "1500" watt rating, this amp can not do it on RTTY,
at least on 80 or 160. Better cooling in the output tank area is
definitely called for.
5. When the amp was about nine months old, the 3CX1200A7 blew with no
warning. Calling CQ on 15 and all of a sudden, a loud bang and the
lights went out. Turned out the tube shorted from grid to anode.
Luckily there was no other damage, and Ameritron replaced the tube
under warranty with no problems. This is no fault of Ameritron's of
course, but it happened.
6. The amp arrived from the factory with the glass chimney smashed
into a zillion pieces. The chimney had been wrapped with paper which
contained the mess, fortunately. The chimney was taped down to the
chassis with one piece of masking tape which was totally inadequate to
hold it. Just careless planning. Ameritron did rush out a
replacement, no questions asked. I do give them credit for that.
So as you can see, the AL-1200 has it's problems. I have used it hard
for the last year and a half, and aside from the above, it's done the
job just fine. However, if I had to do it again, I wouldn't buy one.
I'd either get an Alpha or build a battleship-style homebrew. Since I
don't care to spend what an Alpha costs, I am building an 8877
homebrew which is about 80% done. It will cost about half what the
Ameritron did and should be about twice the amplifier. You'll be
hearing it by summer.
Anybody want to buy a used AL-1200?
I thought so.
73, Bill W7TI
wrt@eskimo.com
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