I wouldn't specify a particular amp manufacturer to avoid. Some models are
better than others, but most that have issues are easily fixed. Most Ham
grade linear amplifiers are fairly solid. I think the answer should focus
on what kind of tubes does it use.
Any of the 3-500Z amplifiers are easy to buy tubes for. They are rugged.
The only real limit is cooling and power supply. Amplifiers with external
supplies and blower/chimney cooling will stand up to abuse better than the
SB-220 and equivalents with small power transformers and simple fan. Amps
like the original Henry 2K use 3-400 tubes which haven't been made in
generations, but these can be replaced with 3-500 tubes (you need to replace
the chimneys too).
The next I would choose is the 8877 type amps. This my personal favorite
tube. These are very rugged and are easy to drive. New tubes are
relatively inexpensive ($800 for Eimac and $600 for others) and MRI pulls
can be had for $200-300. The king of these amps has to be the Alpha 77Dx.
The Henry amps like the 3K w/ 8877 are good and Ameritron's are plentiful.
There are a lot of amps using the Russian 4CX800. Most have a very good
reputation, but the prices on these tubes has just gone up and come close to
Eimac 8877 range.
3CX1200 based amps like the Ameritron AL-1200 and some Henry's are decent.
These run in the $800 range to replace. The tube is virtually
indestructible.
572B and 811 amps are very inexpensive to buy tubes for but don't expect
rock crushing power with these. The 572B is comfortable at about 1000W out
and 811 at 600W.
Then there are the 3CX800. I am not a fan of this tube. It is very fragile
and a new pair will cost near $1400. There are some who substitute 3CPX800
broadcast and MRI pulls for much less.
STAY AWAY from 8875. They aren't made any more. The Alpha's with 2-3
8874's are very expensive to retube and the conduction cooled 8873 is
another very expensive one.
Others to avoid are the vapor cooled (also called Stanley Steamer's) Alpha's
and Henry's. The 3CV1000 and 3CV1500 tubes haven't been made in decades
and are impossible to find, although Econco will rebuild them if it is
intact.
GL de Mike, W1NR
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|