[time-nuts] Spectrum Analyzer Specifications

jimlux jimlux at earthlink.net
Thu Mar 24 09:04:43 EDT 2016


More like $40 in parts, without a board, etc.
The RPD-1 is $20.70
LT1678/LT1679 is a nice low noise opamp that does rail to rail and is 
about $5
etc



On 3/24/16 4:42 AM, Bob Camp wrote:
> Hi
>
> Pretty simple:
>
> Double balanced mixer, RPD-1 is one option, there are others.
>
> Fairly simple L/C lowpass between the mixer and an op-amp.
>
> 20 db positive (non-inverting) op-amp amplifier string after the mixer
>
> Output of the string goes to the sound card. Use a good (dual / quad) audio op amp
>
> Quadrature amp picks off the output of the first op amp stage, switch and resistors to set gain, pot to set op point.
>
> ====
>
> So what you have is an old style quadrature phase noise amp and “PLL”. More or less a very junior version
> of the 3048 test box. Like any setup of this sort, you check two similar oscillators. They run in quadrature and
> you do a few “measure this with switch in position A” sort of things to set things up each time.
>
> Nothing exotic.
>
> Bob
>
>>>
>>
>> Any documentation on this $40 phase noise test set?
>>
>> Rick N6RK
>


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