On Tue, 2007-11-06 at 05:33 -0800, Dennis OConnor wrote:
> What Rick, are you saying that my O2 is not a mobile rig?
>
> OK levity aside, I agree with you... I would comment that SGC may be small
> but their 500 watt amp, is of the highest world class quality... When I
> opened mine to enable ten meters I was blown away by the quality of the
> build... It matches anything I saw in my wasted youth in industry...
> My testing shows that the SGC500 is capable of 650 watts out (with a rock
> solid 14.8 volts in - I use a pair of Diesel starting batteries and a charger
> ) ...
That raised voltage gets some more power out, but it adds to the voltage
stress on the active devices which is made rapidly worse by a mismatched
load.
Trouble with driving all amplifiers to more than rated output is that
there is often gain compression in those extra watts and that means
significantly increased distortion. Sometimes most of the extra watts
are in distortion products, not in the original signal, but splatter and
harmonics. Many amplifiers will do more with a carrier than they will do
peak on SSB and still be linear. Just something to watch out for. Some
UHF modules will do nearly twice the CW or FM power they will do
linearly for SSB. That applied to tubes too, especially sweep tubes.
> Now picture a mobile pair in push-pull giving you 1300 watts out and each
> amp having a 50% duty cycle...
How's the "push pull" get 50% duty cycle? Isn't the individual amplifier
already using the transistors in push-pull and aren't they biased one
significantly so they run class AB or B, never in class C. Then running
two amps you run a power combiner and to get that doubled power BOTH
amps have to work full time. No 50% duty cycle unless you run them in
class C and then the linearity isn't.
> Hmmm, picture me salivating... Picture the mobile whip begging for mercy...
>
> Lets see, I do have an old metal workbox that fits across the bed of my
> 4X4...
> It would hold the amps and fans, and the batteries can be in a plywood box
> right next to the amps box, then a 2KW Hush Power generator to charge the
> batteries and a fuel tank plumbed ot the generator...
> CQWW mobile anyone?
>
>
>
>
> denny / k8do
73, Jerry, K0CQ
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