Rob, just out of curiosity, what is the key down time on the 2.5 KW THP?
73, Joe
K2XX
On 4/29/2012 1:11 PM, Rob Atkinson wrote:
>> Most of the tube designs have been significantly "over engineered".
>> That is, the tubes have excess plate dissipation for the power output
>> and grids that will take a significant beating.
>>
> What you are saying is tube amps would fail if they were not "over
> engineered" but assuming you are correct and they are, then they are
> in fact more robust so reality trumps theory.
>
> 3-500z with 20 w. grid dissipation is a tube you pretty much have to
> deliberately damage, in order to damage it.
> I don't know how often unobtainium FETs show up at flea markets but
> you can often find tubes out of production--3-1000z, 4-1000...sure
> they may not be cheap but at least they are there. Most of the amps I
> have seen with tubes that become unobtainium were goofy one-offs that
> should have never been made. Stick to buying an amp that uses a tube
> that is also used in amps made by a number of other manufacturers and
> you'll probably never be hung out to dry.
>
>> Given proper design and protection, modern solid state devices will
>> last a lifetime unlike tubes that *will* need to be replaced due to
>> filament/cathode aging. Transistor amplifiers don't suffer from
>> catastrophic arcing and certainly don't represent the electrocution
>> danger of tube amplifiers.
> Dangers only to hams who don't know what they are doing. I guess it
> is easier to make a s.s. amp appliance operator idiot proof but making
> one as bullet proof as a tube amp costs a fortune. The Dishtronix
> amp, about the only s.s. HF amp I have seen that comes close to being
> on a par with a 1.5 kw tube amp in a number of ways is around $10,000.
>
> 73
> Rob
> K5UJ
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