[time-nuts] TADD-1 six channel RF distribution amplifier

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Mar 28 21:51:32 UTC 2008


Steve wrote:
> Thanks for the info Bruce.
>
> I'm planning to use the Trimble Thunderbolt as the 10MHz source.
>
> The phase noise characteristics of that device are on the Trimble web 
> site. I'm not versed enough in the specifications to call it good, bad 
> or mediocre with respect to phase noise. Thoughts?
>
> Thanks.
>
> Steve K8JQ
>
>   
Steve

If one compares TvB's plot of the phase noise of a Thunderbolt with John 
Ackermann's plot of the phase noise of a TADD-1 at 10MHz.
Then the phase noise floor of this particular Thunderbolt is lower than 
the phase noise floor of the TADD-1 at the particular gain used in 
John's test.
Thus using the TADD-1 at this gain will degrade the noise floor of that 
particular Thunderbolt by about 7dB.
However at 1Hz and 10Hz the phase noise of the Thunderbolt exceeds that 
of the TADD-1 by 15dB or more so the phase noise of that Thunderbolt 
will not be significantly degraded by the TADD-1 at those offset 
frequencies.

Distribution amplifiers with lower noise floors and equivalent or better 
reverse isolation do exist but tend to be expensive.
A design employing cascaded common base stages can have a significantly 
lower phase noise floor.

Bruce




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