Please pardon the previous incomplete post, same
subject from me, this is the one intended:
> Given that the spec for IP2 is +75dBm, I hope T-T will
> take a look at what caused this discrepancy -- and
> whether it was an anomaly of the radio that ARRL had
> for test, or whether it effects 'em all.
I thought the Orion Main rcvr did not receive much from
outside the amateur bands. Here are the parameters of
the ARRL test and the reported data:
"Second-Order Intercept
Test Description: This test measures the amount of 2nd-order
mixing that takes place in the receiver and calculates an
intercept of the second order response with the on-channel
response. Signals at 6 and 8 MHz are presented to the
receiver and the resultant output at 14 MHz is measured.
Test Results:
Frequency..Preamplifier. Mode. IP2 (dBm). Notes
14.02 MHz.... Off........... CW.. +63.0... Main Receiver
14.02 MHz.... On........... CW.. +63.0... Main Receiver
14.02 MHz... N/A............ CW... +43.1.. Sub Receiver
Note that the test signals input to the Main Rcvr for
the test are at 6 and 8 MHz!! Frequencies to which the
main rcvr is alleged to be deaf!!? What is really going on
here and what does the test data mean??? Just some readings
on a Audio Voltmeter, but what was really being read?
Of course the Sub rcvr is "open" to those frequencies.
Inquiring minds are wondering about this; I suspect it
is NOT possible to measure 2nd order products of the
Orion main rcvr, if so how? These occur as f1+and-f2,
and 2f1 and 2f2. There for, one way, legitimate to
measure, it seems to me, for example would be to
generate a signal at 7.01 MHz, and read the output
at 14.02, the data readout frequency the ARRL labs
chose. Now that could be a legitimate test, but not
6 and 8 MHz input which would "mix" to an f1+_f2
result of 14.00MHz, and not 14.02, by the way.
73, Jim KH7M
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