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

[jeremy-ca]

----- Original Message ----- 
From: "Edward J White" <wa3bzt at verizon.net>
To: "Discussion of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Tuesday, December 25, 2007 4:39 PM
Subject: Re: [AILtech] Re: [Test-Equipment] LF Ailtech 7514 and noise sorce


> 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.

The AIL's require a mixer for above 30MHz and are great when working with 
vacuum tube preamps and early solid state. They are not for working with the 
GaAs FETs and later technology due to the inherent limitations of 
measurement accuracy.


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


The HP 8970A & B will measure directly to 1600 MHz  and 2047 MHz for the B 
model with Option 20. The B will also drive a plotter and I believe PC 
control over the HP-IB is possible. The setup instruction set is also a bit 
different for the B. They are microprocessor controlled and the AIL is all 
manual.

The 8970A has less demand in the market so prices are often low.

HP noise sources are fragile and expensive, use of a pad ahead of the DUT 
prevents damage. NoiseCom has a source that is less sensitive to damage and 
a bit cheaper.


>
> I am just trying to figure what I would need to test some rec amps for 50 
> MHz to 10 GHz>


The HP or something similar. The 8970 is the standard for all the noise 
measurements tests at the conventions, hamfests, etc.
It can be a real PITA to setup, the enclosed pull charts leave a lot to be 
desired so be sure to get the manual.

Carl
KM1H



> Any help will be great. Maybe I need to do more research on the internet 
> or some where else.
> 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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