[Amps] MLA-2500B Question

Mon Mar 28 08:40:37 EST 2005

Hi Daniel - just my 2 cents follow.  Each of these
amps has it's "warts" - some more serious than others
and they have been more than adequately covered both
here and on other reflectors.  So I won't plow that
ground again.  Instead, just my comments and, of
course, YMMV.

I have a Dentron MLA-2500 - not the "B" model and have
had a number of Ameritron 811's and 811H's in the
shack over several years - both for my personal use
and as repairs for others.  The Dentron is brute power
in a small quiet box. I easily get 1300 watts output
from it with about 90 watts of drive - even though it
does not have a tuned input!

I don't know if the "B" has tuned input or not - you
likely do and that may be an important consideration.

The Ameritron 811H is a very nice docile amplifier. 
Reasonable power output (600 to 800 watts output
depending on band) with readily available (and
cheap)tubes and a tuned input.  Most of the guys and
gals on the other end of your qso's won't see the
difference between this and the kw output from the
Dentron.

While the tuned input is a compromise on the higher
frequencies in the 811H, it does a pretty good job. 
The tuned input is important if you are using a solid
state rig and it does not have an antenna matcher
built in or if you don't have an external one that you
can put between the solid state exciter and the
amplifier.  Some solid state rigs are very touchy
about what they look into!

In addition, the Ameritron covers the WARC bands
easily. While the Dentron can be made to work on them
it's a bit sketchy and depending on the plate choke
used in your Dentron, it could go partially up in
smoke when you try to tune it up on the WARC bands.

Ultimately, the amplifier has to meet your
requirements (cost, output, ease of tuning, quick band
change, physical size, availability of 220 vac, etc,
etc) and only you can make those decisions.

For my part, it would depend on the price of the
MLA-2500B - and - it's condition - and - you say it
has good tubes so lets assume it does and that it is
in excellent physical condition.  If it was really a
"great" deal (that depends on your definition of
"great" - mine would be $300 or less - and - btw: I
would not sell mine for less than $675 just as a point
of reference and it does have excellent tubes and is
pristine physicaly).

Given all that, I would probably buy it - but - that's
just me!!  Here is my reasoning 

- I have a number of rigs, each have built-in antenna
matchers so the lack of a tuned input is not an issue
for me. (The important part of this is the "for me!")

- I don't "have" to run the Dentron at "full power" -
just let it loaf along at 750 to 800 watts output.  At
that rate, the tubes should last a very long time! 
But if I need to, I can always "crank it up!"

- The WARC bands don't hold much fascination for me
and I can do what I want to do there barefoot.

- I like the "low profile" look of the MLA-2500 series
as opposed to the somewhat higher and boxier look of
the Ameritrons.

- If the deal is really that good, I could play with
it for a while and then perhaps sell it for more than
I payed for it!!!  BTW:  In over 45 years of hamming,
I've never been able to do that!!  I always seem to
buy high and sell low!!

- Ameritron is not likely to go out of business
anytime soon so the 811H's will be available for a
long time.  The new price may go up but there is
always the used market.

- If the tubes do go "south" in the Dentron, I could
offer the amp for sale without the tubes and could
possibly recoup some or all of my initial investment. 
Then, go buy an Ameritron if I wanted to!

- If the tubes do go "south" I could consider putting
3CX800's or 4CX800's in it an have a super amp!  Of
course, this option depends on your technical skill
and willingness to work on it!  (BTW:  I'd also put
vacuum relays in it at the same time)

Those are just a few of my ideas - 

Now, frankly, from your post, my advice to you would
be for you to buy the Ameritron 811H.  You've already
had one so you know how to deal with it.  It's a
"current" amplifier and really requires very little
technical expertise or hassle to make good use of it.

BUT the real reason for my advice for you to pass the
deal on the Dentron and find an 811H is that you will
always feel bad about selling the 811H that you had
and not getting another one!  That's pretty obvious
from your post - you had a love affair going on and
went to recapture it - or at least try to!

Go with the Ameritron and have fun.  73 es gud dx --
Don N4HH

--- Daniel Hileman <n9wx at hotmail.com> wrote:
> Hi Everyone,
> I have an opportunity to buy a Dentron MLA-2500B for
> a very resasonable 
> price and it still does full output on most bands.
> over a kilowatt or near a 
> kilowatt on all bands with only 50 watts drive. I
> can either buy this or an 
> AL-811H for about the same price. I had an 811H
> before and loved it, I was 
> stupid and sold it when I went to college, Now I
> want it back, but the 
> greater power of the MLA-2500B is VERY tempting! Hi
> Hi.
> My question is, with the 8875 tubes VERY expensive
> or almost impossible to 
> get, would the 811h be  better perhaps for me,
> especially  since I'm fairly 
> new to amps? I know there is a conversion to other
> tubes, but not sure I 
> have the expertise to do this, and probably couldn't
> afford to have it done 
> unless some local "expert"  ham helps.
> 
> I need opinions of this amp, and this situation.
> 
> Thanks,
> Daniel N9WX
> 
> 
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> 

__________________________________ 
Do you Yahoo!? 
Yahoo! Small Business - Try our new resources site!
http://smallbusiness.yahoo.com/resources/ 