On Mon, 24 May 2004 05:46:01 GMT, "Lord Snooty" wrote:

At 8.000 Mhz and a load consisting of 50 ohms carbon 10W 10% in series with a
capacitance trimmer bank, at an output power level of about 2W, a load
capacitor value of 250 +/- 10pF (-j80 ohms @ 8 MHz) was found to produce a
minimum in the total voltage across the load. Also, as capacitance was
increased over the range 100-700pF, the voltage across the load resistor
increased monotonically.

The latter is easy to explain (it means the source reactance is positive, and
smaller than +j28.4 ohms), but the former is beyond my ken.

Best,
Andrew

Hi Andrew,

You got me confused too.

Is the "load" the resistor, or the resistor-cap combination when you
measure these voltages?

You describe a voltage minimum across the load for a cap setting of
250pF; but you also maintain that the voltage across the load
increases for the variation in capacitance from 100 to 700pF which
contradicts the first measurement.

Further, the construction of a high power semiconductor does not lend
itself to supporting inductive reactances (the junctions are quite
manifestly capacitive in structure). By specification the device is
characterized as exhibiting 27pF @ 1 MHz (for 28Vdc although there is
not much variation until below 10Vdc). There are a world of other
variables to consider, but none portray inductance within the device.
This alone should provoke you to re-examine your premise.

73's
Richard Clark, KB7QHC