[time-nuts] GPS splitter

Magnus Danielson magnus at rubidium.dyndns.org
Sun Jun 18 11:56:43 EDT 2017


On 06/18/2017 05:37 PM, Bob kb8tq wrote:
> Hi
>> On Jun 18, 2017, at 11:17 AM, David J Taylor <david-taylor at blueyonder.co.uk> wrote:
>> "David J Taylor" <david-taylor at blueyonder.co.uk> wrote:
>>> .. or a ready-made, and smaller item:
>>> http://www.ebay.co.uk/itm/1GHz-3GHz-2-4GHz-Power-Splitter-Combiner-2-Way-SMA-/141740586696
>>> I use this successfully for 1.09 GHz ADS-B splitting.
>> Please be aware that this is a Wilkinson splitter and thus has a DC
>> path connecting all three ports. You will need to add a DC block
>> at one of the receivers.
>> Attila Kinali
>> =======================================
>> In practice, what would happen if you didn't have the block?
>> Say with two identical receivers?
> As long as they both are powered up, noting much. If one looses power, it *might* try to power
> up the other one via the antenna feed. With most receivers, even that would likely just be an
> odd occurrence / no damage caused. The fear is that you have a receiver that *would* be damaged
> by the back feed. With eight receivers into a coupler, there *could* be quite a bit of current available.

As you power up, there can be a bit of a rush-in power.

Lack of isolation can cause antenna power detection to be confused.
Two driving one antenna => too little current => judged as unconnected.
One driving antenna and other GPS => too much current => judged as short 

If you have different voltages, it might be bad for the low-voltage device.


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