David J Windisch wrote:
> Would this amp be a good platform for experimenting with an eye toward a
> 1.5kW continuous output setup?
>
From my view: Probably not.
I say this as these amps consist of a lot of very fast protection
circuitry for over voltage, over current, over drive, a trip of
reflected power, temperature, and most check to make sure the drive is
on the proper frequency.
They use all this ultra fast detection and protection circuitry to
protect what are often called the fastest fuses on three leads and those
three legged fuses are expensive.
Certainly there is *some* headroom built in. There has to be or the
reliability would be nil. How much head room is pretty much an unknown
although a bit of research should turn up max voltage, current, and
temp. "I'd think" about the only place for any safe improvement would
be in the cooling and I'd expect that to only allow a marginal increase
in power. Depending on how careful you operate and nothing affects the
antenna you could *probably* reduce the headroom on the protection
circuitry. Unfortunately a broken element, insulator, or even a stray
branch from a tree could put the system where one spike could wipe out
one or all of the transistors.
Now if a person is willing to spend money and in this case it's likely
to be substantial (a relative term) for higher rated transistors to use
in place of the originals AND play a bit with the impedance matching,
then those voltage, current, and temperature limits could be adjusted
accordingly.
I'm not familiar with the workings inside the Quadra, but my guess is
most of these high power solid state amps are similar in both the
amplifier circuit and protection circuitry and when similarly equipped
they have similar prices. For example the 1.5Kfx is a bit less
expensive than the Quadra until you include the external autotuner
(which the Quadra has built in IIRC) then they are about the same price.
I have the Tokyo Hy-Power HL-1.5Kfx which when running 1KW out (which
happens ONLY when the SWR is 1:1) there is very little heat coming off
the heat sink even in long winded QSOs. OTOH they do have an auxiliary
fan for additional cooling when running RTTY, or slow scan.
> I am not concerned with resale value, since I never met a piece of ham gear
> which couldn't be improved <BIGGRIN>
>
I believe several on here have, or are building up legal limit SS amps
based on the 1.5 or 2.5 Kfx amps. It's something I'd like to play with
but just don't have the time. Too many other projects.<:-))
73 and good luck,
Roger (K8RI)
www.rogerhalstead.com
> Tia and & 73'
>
> Dave, N3HE
>
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