[time-nuts] how to find low noise transistors

Alex Pummer alex at pcscons.com
Sat Jul 18 19:16:42 UTC 2015


but be sure that you have a hp4470B --a transistor noise analyzer  [ 
http://www.testequipmenthq.com/datasheets/Agilent-4470B-Datasheet.pdf ]
73
Alex

On 7/18/2015 8:47 AM, Pete Lancashire wrote:
> I agree with Bob, find a vendor you can trust and make sure you buy from an
> authorized distributor or if just need two or three parts try to get them
> as samples.directly from the manufacturer. The reason for this is you may
> get a fake or reject part and you will never know.
>
> Trying to do the measurements yourself is pretty much out of the question
> today.. Every improvement made it harder in that the equipment had to
> itself be lower in noise
>
> If interested
>
> https://scholar.google.com/scholar?q=measuring+transistor+noise&hl=en&as_sdt=0&as_vis=1&oi=scholart
>
>
>
>
>
> .
>
> -pete
>
>
>
> On Sat, Jul 18, 2015 at 5:29 AM, Bob Camp <kb8tq at n1k.org> wrote:
>
>> Hi
>>
>> You have (and always have had) two basic choices:
>>
>> 1) Buy a very expensive part from somebody who has gone to the trouble
>> of characterizing the noise performance and will guarantee at least some
>> of what they show on the data sheet.
>>
>> 2) Buy a bunch of cheap transistors and test them. Lock in on a
>> specific part and vendor. Keep monitoring what you get in case they
>> “improve”
>> their process and the magic goes away.
>>
>> How do you select candidates? That’s never been easy, there is less and
>> less data on the sheets every day. Normally the first step is to look at
>> a vendor that you have had luck with in the past. The next step is to ask
>> them…
>>
>> Bob
>>
>>
>>
>>> On Jul 18, 2015, at 5:16 AM, Attila Kinali <attila at kinali.ch> wrote:
>>>
>>> On Fri, 17 Jul 2015 23:25:10 -0400
>>> Charles Steinmetz <csteinmetz at yandex.com> wrote:
>>>
>>>> A pair of Zetex (Diodes, Inc.)
>>>> ZTX849 or FZT849 actually have significantly lower voltage noise than
>>>> either the LM394 or MAT12.
>>> I always wonder how you figure out whether a transistor is low noise
>>> or not. What part of the datasheet hints at which transistors have low
>>> noise and which have not? Even if it's just try and measure, how
>>> do you find good candidates to measure?
>>>
>>>                        Attila Kinali
>>>
>>> --
>>> I must not become metastable.
>>> Metastability is the mind-killer.
>>> Metastability is the little-death that brings total obliteration.
>>> I will face my metastability.
>>> I will permit it to pass over me and through me.
>>> And when it has gone past I will turn the inner eye to see its path.
>>> Where the metastability has gone there will be nothing. Only I will
>> remain.
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