The DTR-2000L doesnt even meter grid current of the 8877 and there is no
tube fault circuitry.
Mods exist.
Early models used a muffin fan to cool which were later changed to a real
blower. Stock amps will barely do 1400W due to low B+ and there is no tuned
input network. Built during the days of 1000W Input on CW and 2000W PEP
Input on SSB.
The octal based time delay relay is becoming expensive and scarce so more
mods are needed.
Other than that it works well; Ive had one sitting on a shelf mostly doing
nothing for 25 years other than an occassional run as an AM linear and to
keep the filter caps formed in case I suddenly need it as a backup. It is
completely stock with original 8877 but at 20-25W of drive the grid is safe
from mistuning.
Dont laugh too hard but a Clipperton L or Clipperton QRO can be turned into
an excellent amp with a little work. Runs 4 572B's and with that work even
Chinese tubes run cool and stable. Im finishing one up now that runs
1100-1200W out with 100W drive, 160-10 with a new set of direct from China
tubes.
They come with 3 input circuits
1. None
2. So-So tuned input
3. Better tuned input also used in the QRO, none are adjustable so some SS
exciters require an external/built-in ATU or an all new input board.
Outputs differ a bit but none work as is on 12 or 17M or both. The Ameriton
plate choke takes care of that.
An Alpha 76 CA or PA is a fine amp if it comes with excellent tubes which
are three 8874's. Drive it light to 1200-1300W and they will last a long
time. Not a WARC amp without mods. The 2 tube 76 version is straining to
make 1200W which is why I dont suggest the Alpha 78 either or the earlier
274/374 2 tubers.
None have grid protection so always watch the meter.
If money is tight an AL-80B will do about 800W on 160-10. The AL-80A and
SB-1000 clone is a bit light on the transformer and a few other areas. The
LK-450 is a rugged single 3-500 ampas a are a few lesser known models that
quickly came and went.
The B&W PT-2500A is another low production amp that easily does 1500W with a
pair of 3-500Z's, early parasitic and low band arcing problems were fixed
but serial # before about 35 are suspect as to being upgraded. Under 300
total were built in the US and a small earlier run as the Viewstar 2500A
fron Canada. Viewstar made a few other models that were seldom seen in the
US.
Carl
KM1H
----- Original Message -----
From: <n8de@thepoint.net>
To: "Pete Smith N4ZR" <n4zr@contesting.com>
Cc: <Amps@contesting.com>
Sent: Tuesday, March 12, 2013 7:40 AM
Subject: Re: [Amps] What Old Amp to Buy?
Pete,
If you can find a Dentron DTR-2000L in good condition .. or even a
Clipperton-L .. they make good 160m amps .. as long as you don't run RTTY
there.
Some guys on here will put those amps down, but, for the usual 'used'
price, they are a bargain.
Oh ... of you find a DTR-2000L that has NOT been retrofit to some other
tube, and you decide NOT to buy it, CALL ME, as I am interested!
73
Don
N8DE
Quoting Pete Smith N4ZR <n4zr@contesting.com>:
With Dayton 2 months away, I'm pondering whether to try to buy an
amplifier in the flea market, in order to add 160M QRO to my
repertoire. If you were looking, what would you be looking for? Don't
have bags of money, and am very happy with my SB-220, so maybe I should
leave well-enough alone?
What would you do?
--
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
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