[time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Magnus Danielson]

Poul-Henning,

On 12/19/2015 10:11 PM, Poul-Henning Kamp wrote:
> --------
> In message <56757344.2020904 at rubidium.se>, Magnus Danielson writes:
>
>> The isolation strategy says that the various equipments should only be
>> power grounded, as required for personal safety, and then have all other
>> grounding paths "galvanically separated" (thus, DC and power frequencies
>> separated in common mode).
>>
>> The mesh strategy says that you extend the grounding of the power ground
>> with additional grounding with every cable and additional grounding
>> cables.
>
> Please bear in mind that there is a *huge* difference between
> single-ended (as in: RF-Coax-BNC) and balanced (as in: Audio-Twinax-XLR)
> for both of these scenarios.
>
> While you can get away with the isolation strategy with balanced,
> because you have high CMRR inputs, there is nothing to "take care
> of" the ground potentials in the single-ended mode.

Oh yes, indeed. I've worked both fields.

>> As a reference, Ethernet is designed to work in an isolation BN setup,
>> [...]
>
> That is actually a new thing, the original Ethernet was 1/2" coax
> and ground-loops and lightning damage was the order of the day.

Well, it's been a long time since that was Ethernet.

> The main reason Ethernet went balanced was actually for fault
> isolation (star-topology vs. bus) and signal quality (IT people
> were horrible at "sharking" and crimping coax.)

The way they destroyed yellow cable with their attempts to drill for 
their vampire... yes. I've seen that too.

Cheers,
Magnus