On 4/4/2011 12:00 PM, Damon Stewart wrote:
> <snip>
> Cheat? In what way? Sorry, I don't contest.
>
> Dont tell me you one of those who believes all cars should only make
> just enough HP to reach the speed limit as anything above that would be
> frivolous.
>
> My belief is the best 1500 watt amp is one that can run 3KW with ease.
> I don't believe in pushing equipment to its limit, rated or not.
Just my opinion but:
It's been my experience that "at least in commercial ham amps" if you
are going to run digital, or any high duty cycle mode, a true 1500 watt
amp needs to be capable of nearly twice that to hold together. Some are
limited by air flow, some are limited by emission, but most are limited
by the PS. An 8877 should be capable IIRC of about 2500 PEP out (I
don't think they'll do quite that much, but close).
The problem is "most hams are cheap" and manufacturers have to cater to
that. So you find amps running tubes way more than for what they are
rated, and even legal limit amps a bit short on iron. Hams also want
nice, neat, and small table top amps they can more around like a
transceiver. They may work great for the casual QSO unless your long
winded like me. Plus I'm probably about as cheap as any one with the
exception that there are areas where I do not believe in compromising
reliability for cost. Amps are one of those. Be it desk top or console
a true legal limit amp is *heavy*. If it can be moved around easily it's
probably a bit shy in the power supply department.
If you want an amp to run 1500 CCS it will likely be able to do close to
2500 out PEP ICAS.
The Chinese FU728F will run about 2500 PEP or 2 KW nominal and makes an
ideal "legal limit" amp. It's pretty much the Tetrode equivalent of
the 8877. The Emtron DX-2sp uses the FU728F and has a multi speed
(push pull) cooling arrangement that is temperature controlled and very
effective.
I understand that even the popular YC156 will happily run the legal
limit with just 3 KV on the plate and something like 40 W of drive and
doesn't take a lot of cooling at that level either. Plus it just bolts
to the chassis with no socket required. It's big, heavy, and readily
available as a tested pull for way less than a used 8877. Run that way
it should still be going strong for generations to come. The only thing
I don't like about it is the long warm up time.
73
Roger (K8RI)
> Cheers!
> Damon Stewart, KJ7E
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