[AILtech] Re: [Test-Equipment] LF Ailtech 7514 and noise sorce

[J Forster]

QTH.net  is a real PITA. It sends out HTML, but insists on plain text
input. Hence this repost.

***********

Basically, a noise meter uses a noise source that switches on and off at
a slow rate (typically under a hundred Hz or so) with
known noise output. The noise source is connected to the input of the
DUT and the output of the DUT is measured. The
difference between the outputs with the noise source on and off is used
to compute the NF or Noise Temperature of the DUT.

Noise sources are calibrated in dB ENR..  Excess Noise Ratio...  which
is the ratio of the source's output to that of a 50 Ohm
termination. The noise source must be calibrated over the range of
frequencies used to test the device.

Typically, the output of the DUT is mixed and converted to 30 MHz or
some other IF frequency then the noise is measured.

There is a Yahoo Group about, among other things, about AIL NF
Instrumentation:

 http://groups.yahoo.com/group/AILtech

Best,
-John


Tod -MN wrote:

   I have read the messages on this topic with some interest. I wonder
if
  someone could supply me with information about how one uses such a
device.
  Perhaps just point me to where I can get some insight as to how it is
used
  and what frequencies are the most likely to be of interest.

  Thanks in advance for any information.

  Tod, K0TO