This InStock Wireless 4-Way splitter is a *passive* device, meaning no
amplification is included. The headline spec of "Insertion Loss 0.4 dB
typical" may be true but does not tell the whole story. Below that spec,
is the column heading of "Insertion Loss Above 6.02 dB" explaining that
each output is down 6 dB due to the 4-way power split without
amplification. Thus their Marketing Department is emphasizing the low
insertion loss but downplaying the loss due to power splitting without
amplification.
This may be adequate if you have enough gain in your GPS antenna and low
enough loss in the coax down feed but it may not be what you expect when
casually reading the InStock Wireless spec. Power splitting is splitting
power; if you divide power 4 ways, each output has to be 6 dB down.
On the good side, this splitter does work on other GNSS systems.
And, they offer (SMA in this case) 50 Ohm terminators, which should be
used on any port that is not connected to a receiver.
Very few GPS splitters need a Bias-T because they typically have one
port that passes through the antenna voltage provided by a receiver,
usually the one connected to Port 1. The other ports are dc blocked.
The GPS Source S14WI 4-Way splitter (as configured) I described here
previously is amplified and has a more sophisticated method of deriving
the source for the antenna voltage, detecting which port, starting at
Port 1, has source voltage available and using that port while dc
blocking the other output ports. When I bought my NOS units several
years ago on eBay, I paid $65 each plus some modest international
postage; I considered that a great price!
Output ports connected to a receiver but not the one powering the
antenna should present a dc load to each receiver so that the antenna
failure detector in the receiver does not falsely report an antenna
failure. Most GPS splitters include a dc load, often 200 Ohms, to output
ports not powering the antenna.
I do have Type N 50 Ohm terminators but currently each output port on my
splitter is connected to a GPS device.
There is a GPS Source 4-Way multi-GNSS splitter offered on eBay now as
Item 401835679864. However, I don't have a data sheet explaining the
model number letters shown to know if this is an amplified splitter or
not; both passive and amplified versions of the S14 splitter are
available. The eBay listing title reads, "GPS Source 1x4 Stamdard
Amplified Splitter - S14 (S14S-E-SF)" but I would not take that as a
guarantee this particular model is amplified since both versions are
offered with that same basic model number. Am I a bit cynical? Well,
maybe...
Larry
On 4/30/2020 2:38 AM, Chris Burford wrote:
I use a 4 port splitter from InStock Wireless, all with SMA jacks. You can
view the specs here as well as browse for other configurations. To help with
the attenuation factor use the lowest loss coax between the splitter and the
GPS antenna. I'm using Times Microwave LMR-400 for just that reason.
https://www.instockwireless.com/gps-splitter-4way-SMA-gps410.htm
Chris Burford...
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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