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

[J Forster]

Edward J White wrote:

> Hi John:
> what does the Ailtech 75 and 7514 unit do. The way the write up reads
> the noise source  works a bandwidth of frequency's that goes into the
> DUT and the output than goes into the Ailtech 75 or 7514? Or do you use
> a mixer to convert the output of the DUT to 30 MHz which is the input to
> the Ailtech 75 or 7514.

Unless the DUT operates at 30 MHz, you need a mixer and LO to down convert.
Some instruments have the mixer/LO built in or as an option. From memory, the
75 is a general purpose unit, the 75xx is a system noise monitor. I can look
in an old catalog if needbe. The 75xx is a newer unit.

> What is the difference between the Ailtech 75 and 7514 how about the
> HP-8970 A &B do they work the same?

I've not dealt with the HP units.

> I am just trying to figure what I would need to test some rec amps for
> 50 MHz to 10 GHz>
> Any help will be great. Maybe I need to do more research on the internet
> or some where else.

It may be hard to find a noise source to cover the full range in one unit.
I'll take a look for you later today.

Really, try the AILtech list. Some of the people there are more expert than I
and have the catalogs more readily to hand.

Best,
-John

>
> Ed
> WA3BZT
>
> J Forster wrote:
> > 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
> >
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