[time-nuts] Build my own dist. amp ??

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Dec 13 13:17:04 UTC 2008


Rex wrote:
> Bruce Griffiths wrote:
>   
>> For a 10MHz isolation amplifier you dont need any transistors much more
>> exotic than 2N3904's in an appropriate package.
>> 3 or 4  2N3904's per isolation amplifier stage will with careful design
>> and layout achieve a reverse isolation of more than 130dB.
>>
>>
>> Bruce
>>
>>   
>>     
>
> Bruce, you seem to have a tendency to tantalize. Couldn't you have 
> pointed him to a reference (or two) to a pretty-darn-good circuit 
> implementation that uses transistors?
>
> I admit, I read most of the posts, but often I lose track and can't 
> figure out if consensus is being achieved in the long threads.
>
> Also, only being casually into all these time/frequency issues, I do 
> lose track of some of the simplistic better things I thought I once knew.
>
> Do we, or should we, have a FAQ? I know there are a couple or more great 
> repositories provided by members. Many thanks to all you guys. But it 
> seems like a lot of this could be covered by -- oh yes, go read number 7 
> and then come back if you need more.
>
> Has this been discussed before? Should we start a new thread or should I 
> just shut up?
>
>
>
>   
I've collected links to most of the useful references on isolation
amplifiers are at the bottom of:

http://www.ko4bb.com/~bruce/IsolationAmplifiers.html
<http://www.ko4bb.com/%7Ebruce/IsolationAmplifiers.html>

However, they don't include the earlier, less useful designs like the 2
JPL versions.


Rather than using perf board it would be better to assemble a TADD-1:
http://www.tapr.org/kits_tadd-1.html
Performance for which is shown:
http://www.febo.com/pages/amplifier_phase_noise/

http://www.leapsecond.com/pages/tadd-1/


To achieve good reverse isolation a good ground plane is essential.
If necessary one can use point to point wiring over a ground plane.

Once you've read these and decided if you want to build a discrete
distribution amplifier, I can show how these circuits can be used in
distribution amplifiers.


Bruce




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