[TenTec] Argonaut V ARRL Review 3rd and 2nd IPs ?

[Jim Reid]

Hmmmm........

The ARRL lab came out with IP's well below the
Ten Tec specs;  seems odd.  TT spec is +4 dBm for
the third order IM intercept point,  at least that is what
the ARRL lab test reports TT has specified.

At 3.5 MHz, 20 kHz  signal spacing,  the ARRL claims to 
have measured only -4.5 dBm;  and at 14.2 MHz,  only -3.4 dBm.
Those are really significantly lower numbers than the allleged
Ten Tec claimed spec.  And,  for 5 kHz signal spacing,  the
deltas are even greater:  3.5 MHz,  ARRL says -30 dBm;
and for 14.2 MHz,  -29 dBm.  Those are huge differences
IF TT really specs +4 dBm IP3 for the tested spacings
by the ARRL labs.  

Also,  TT,  they say,  specs the second order IP to be +66 dBm.
But the ARRL lab reports only +47 dBm.  Again,  a very large
difference.

No mention seems to occur about these deltas in the verbose text
by the reviewer about the rig; his only comment, "The third-
order  intercept was in the negative numbers..........".

Wonder how the engineering team at Ten Tec,  and the techs
in the ARRL labs are doing things differently to arrive at such
diverse test results?  I don't believe the Argo V has an RF
preamp which can be turned ON/OFF.  If it does,  then the IPs
will change by the gain of the preamp;  they will drop about the
same as the preamp gain IF the spec as given,  is with
the preamp OFF.  Note there is an Attenuator button on this
Argo,  does it turn off a preamp,  or actually insert loss?
Was the Attenuator ON or OFF for the tests;  what is the
intended Ten Tec setting of the Attenuator for their claimed
+4 dBm 3rd order IP and +66 dBm 2nd order IP?

Oh well,  some explanation will come along from someone,
I am sure.

73,  Jim  KH7M