[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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