The solid state PA, especially at 12 volts, is very particular about the
supply voltage IN the radio. A small drop hurts the power output, so if
the power supply regulation isn't perfect, the power leads aren't heavy
and short, and the power connectors perfectly clean and tight that will
lower the available power output by a few percent or more.
Then in my experience, the internal directional couplers used for power
output (ALC in solid state) and SWR are not as sophisticated or as
precise for minimum SWR = 50 ohm load nor perfectly flat from 160
through 10m as to better external meters and couplers.
And while a Bird is the industry standard, it has a calibration
tolerance of 3 or 5% of full scale which means reading 5 watts on a 100
watt scale has a reading tolerance of +/- 100% if the meter tolerance is 5%.
All couplers have finite directivity, which means the forward power
reading may be off a little if the load impedance isn't perfect at 50
ohms. Directivity tends to vary quite a bit with operating frequency.
73, Jerry, K0CQ
On 4/1/2011 9:04 AM, wa3fiy@radioadv.com wrote:
> 'Couple things,
>
> The difference between 88 watts and 100 watts is about 0.55 db which is
> slightly less than
> 0.1 S unit (using 6db per S unit). Can anyone hear that difference under
> anything other than
> lab conditions? Can anyone hear 0.55 db difference under any conditions?
> Probably not.
>
> BUT you say...."I bought a 100 watt transceiver and I want a 100 watt
> transceiver!" OK, no
> biggie. First of all, get a lab standard power meter and dummy load and set
> everything up.
> Then adjust the two pots (it's two pots in most of the later TT rigs. Not
> sure about the Eagle
> though) in the radio to calibrate the radio power and alc such that you get
> exactly 100 watts.
> Not hard. I've never seen a 100 watt TT radio that would not deliver at
> least 120 watts or so
> if you coaxed it. The radio can do it but why do it?
>
> In fact, I generally calibrate my radios so 100 watts indicated is well under
> 100 watts, 80 to 90
> typically. I rarely ever operate over 50 watts. Why? Because that's all
> I normally need and
> every thing runs cooler and cleaner. If I need more, I fire up the amplifier
> and get about 500+
> watts with 50 watts drive.
>
> We're not buying a lab instrument...we're buying a radio. In the case of the
> Eagle (and most
> other radios I imagine), they do quite well at that task.
>
> To each his own. But you can have it spot on if you so choose.
>
>
> -Lee-
> WA3FIY
>
>
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