I wrote:
> It seems to me, that the fact that the indicated output power
> on the test instrument was +63dBm with the preamp both
> Off and On, further indicates that what ever was being
> read had NO relation at all to the input signal attempts
> to the Orion and 6 and 8 MHz.
The test instrument DOES NOT readout +63 dBm as I
wrote above! But some output power well below that
number. The IP2 number of +63dBm is an EXTRAPOLATION
to the intersection of two straight lines whose slope has
been measured at much lower power levels from pairs
of measured input signals. If the input powers of the test
signals at 6 and 8 MHz were measured, written down then
plotted on log/log paper against the output powers, linear
output signals would rise with a curve slope of 1, while
the 2nd order output power signals would rise with a slope
of 2. Therefore, these sloping lines could be extrapolated
up to the much higher "intercept point" power represented
by the +63dBm number given out by the ARRL lab.
BTW, the Orion design shows input band pass filters for
the ham bands only being passed....so how do 6 and 8
MHz signals get through and how do they get converted
to 9 MHz, the first IF frequency of the Orion by the first
LO, hmmmm? This is the first place where active mixing
to generate IMs seems to be, unless they are also
intermodulating in the front end preamp which is turned
OFF (actually just by passed).
Well, enough from me on this.....just don't understand what
caused the results that the ARRL lab is reporting, given
what I believe I understand about the Orion design.
73, Jim KH7M
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