[time-nuts] Spectrum Analyzer Specifications

John Ackermann N8UR jra at febo.com
Thu Mar 24 13:31:23 EDT 2016


I'd be willing to assist with board layout if someone wanted to make 
this into a real project (e.g., fully developed schematic).  TAPR might 
be talked into supplying at least bare boards; we'd have to get a sense 
of demand before committing to a full kit or assembled unit.

John
----
On 3/24/2016 9:04 AM, jimlux wrote:
> 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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