[Amps] Why hasn't solid state replaced tubes?

Tom Rauch w8ji at contesting.com
Wed Mar 5 10:25:10 EST 2003


> pwr spike overshoot
> === ===== =========
> 100w 100w     0%
>  75w 91w    21%
>  50w 73w    46%
>  25w 52w   108%
>  10w 26w   160%
>
> Run at 13.8VDC into a 50 ohm load.
>
> However, last year we bought another Mk2G here at work to do some testing
> with. For grins I measured it and found it to have significantly more
> overshoot - nearly 120w when set for 100w out, and the other power levels
> had more overshoot as well. So your mileage may vary. 180w is awful.


Run the supply voltage up to automobile voltage levels, when running at
highway engine speeds. At 14.5 volts or so the spike level increases
dramatically.

On my rig (an old 706), using a sample-and-hold digital meter, I have
measured transients that are the same with power setting at 1 or at 10!! The
level of transient goes up at about the square of supply voltage increase.

Not a good thing.

ICOM told me nearly all rigs made by everyone else does that, and when I
mentioned CW problems their manager said "no one works CW anyway, so we
aren't going to fix it". That's why I dumped my 775DSP while I could.

73 Tom



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