There's a reason why the Dishtronix amp is ten thousand bucks.
the sets of cheap and low IMD bulletproof do not overlap.
There are tens of thousands of tube amps that will continue to show up
at hamfests for years to come. Tubes aren't going away anytime soon,
except in the construction pages of ham magazines where anything over
70 v. scares people.
Rob
K5UJ
<<<I presently own a SS 1.2KW ham amplifier. This is my second unit as the
first was replaced when the finals (4 out of 8) FET failed. The unit uses a
total of 8 MRF-150 transistors. Unit #2 is now working fine but I am
cautious about trying to run it at its rated 1200 watts pep output. BTW,
the second unit burned out half of the 8 FETs so the factory has replaced a
total of eight transistors. The only thing I think I have learned is to
NEVER accidently apply 90 watts driving power to the amplifier or to try to
operate it in key down conditions without reducing the RF output about fifty
percent. The factory says it can run 1200 watts output PEP on CW and SSB
but does not give any duty cycles or list at what output it can operate
continuous duty.
I am considering take a step back in history to an Alpha 9500 with a ceramic
8877 and a key down rating of 1500 watts output continuous duty cycle. An
Alpha sounds like a deal compared to a $30,000 amplifier. Rockwell Collins
has nice 1KW and 4KW SS amplifiers. I suppose they would be willing to
sell one to a ham that didn't mind the price tag. Maybe it is time to
design power transistors that can be replaced like tubes. Even a klutz can
change a 8877 if he can afford a replacement and makes sure the high voltage
(3500+) is discharged from the power supply.
Tom AG8K
>>>
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