[R-390] Sensitivity Measurement Question

[Dennis Wade]

Good evening,

         After securing another Z202 from Fair Radio and installing it into
the RF deck and re-aligning that octave, I set about to measure sensitivity
according to Chuck's method as published in the Pearls.  The instructions
specify to set the noise level on the line level meter to -10 db without
the generator connected, then connecting the generator and finding the
level that yields a 0 db reading on the Line Level meter for a measurement
of the 10db S/N + N sensitivity.

           Following this method on the 0 and 1 mhz bands went well,
yielding about 0.3 - 0.35 uv readings.

            The problem I run into on the higher bands (2 and 3
specifically) is this:  I can set the -10 db level just fine, but when I
attach the cable to the generator, it acts as an antenna and the noise
level rises dramatically.  In other words, with the cable connected, and
the RF turned off, the line level is well above the 0 db mark.

            The generator is an HP 8657B.  Feeding the output into a Tek
DCA 602 scope doesn't reveal any added noise over the baseline that I can
discern with just the cable connected with no RF out.

            What am I doing wrong?

 Thanks!

          Dennis

-- 
"If they trust you, it is an extraordinary privilege, and you simply can't
abuse it."
      - A. Alan Post  1914-2011.  California Legislative Analyst 1949-1977.

-------------------------
Dennis L. Wade
KG6ZI
Carmichael, CA