[time-nuts] GPS antenna splitter recommendation?

Bob kb8tq kb8tq at n1k.org
Thu Apr 30 23:29:54 UTC 2020


Hi

With a setup using a (bunch of) broad band splitter(s), you have only one amp. Whatever that
amp needs / does can easily be dealt with. Have a 5V antenna (or 3.3V …) and a 12V amp? 
That’s easier to work on with only one amp. Need to allow the magic new band that just appeared?
Just change the amp. Need some sort of 20 cubic foot filter to take out the new cell phone operator?
It only needs to go on the one amp. 

A more subtle issue is that you may need more than one gain level. Some gear wants 40 to 50 
db of gain in front of it. Other gear is very happy with 15 db. A multi level splitter setup is one 
very effective way to deal with this. 

Still the biggest issue is cost. Broadband splitters are dirt cheap. Inline amps are not much (if any)
more. Hooking A to B to C turns a  $50 setup into something that works as well for your basement as 
the $1,000 gizmo.

The math:

LNA:

https://www.ebay.com/itm/LNA-10K-8000Mhz-High-Gain-Flatness-RF-Amplifier-Low-Noise-25DB-18DB-30DB-20DB/193385250707?hash=item2d06a8bf93:m:mO84pfPOrDC7QE_XD8k5lOg <https://www.ebay.com/itm/LNA-10K-8000Mhz-High-Gain-Flatness-RF-Amplifier-Low-Noise-25DB-18DB-30DB-20DB/193385250707?hash=item2d06a8bf93:m:mO84pfPOrDC7QE_XD8k5lOg>

$10.95 delivered with 18 db of gain.

Bias tee:

https://www.ebay.com/itm/Bias-Tee-Wideband-10-6000-MHz-6GHz-for-HAM-radio-RTL-SDR-LNA-Low-Noise-Amplifier/322365135389?epid=17021762201&hash=item4b0e759a1d:g:YC4AAOSwZoBdJHZU <https://www.ebay.com/itm/Bias-Tee-Wideband-10-6000-MHz-6GHz-for-HAM-radio-RTL-SDR-LNA-Low-Noise-Amplifier/322365135389?epid=17021762201&hash=item4b0e759a1d:g:YC4AAOSwZoBdJHZU>

$4.11 delivered 

DC Blocks should you need them

https://www.ebay.com/itm/5Pcs-2W-SMA-Male-to-Female-DC-Blocker-DC-6-0GHz-50ohm-RF-Coaxial-Block-SWR-1-2/274294980982?hash=item3fdd414176:g:Cn4AAOSw9gtdS7n2 <https://www.ebay.com/itm/5Pcs-2W-SMA-Male-to-Female-DC-Blocker-DC-6-0GHz-50ohm-RF-Coaxial-Block-SWR-1-2/274294980982?hash=item3fdd414176:g:Cn4AAOSw9gtdS7n2>

( or use the bias tee, it’s cheaper ).

Broadband splitter:

https://www.ebay.com/itm/LOT-OF-2-Mini-Circuits-ZB8PD-2-Power-Splitter-8-way/254582653958?hash=item3b464f0406:g:BeQAAOSw6yBeh-Ry <https://www.ebay.com/itm/LOT-OF-2-Mini-Circuits-ZB8PD-2-Power-Splitter-8-way/254582653958?hash=item3b464f0406:g:BeQAAOSw6yBeh-Ry>

Right now that’s two 8 ports for $14 delivered. 

Add a 2 port in front:

https://www.ebay.com/itm/Mini-circuits-Divider-ZAPD-2-2-Way-SMA-1-2-GHz/270724240771?hash=item3f086c1583:g:Al4AAMXQZdFRHvNC <https://www.ebay.com/itm/Mini-circuits-Divider-ZAPD-2-2-Way-SMA-1-2-GHz/270724240771?hash=item3f086c1583:g:Al4AAMXQZdFRHvNC>

That’s $13 delivered. 

So you now have 16 ports giving you 3 x 4 = 12 db of loss (plus a bit) in the splitters. You have 18 db of gain so a net of +6 over all. 
Cost for the three ports the OP wanted to use is 13 + 14 + 11 + 4.11 x 3 = $50.33 .. rounds nicely to $50. If you dropped back to *only* 
8 ports, that gets you down to $37. (yes there is a un-equal gain solution at $37 and 15 ports …). 

The setup as detailed above will give you all the GNSS signals on all the bands. There are no  high delay filters in the system to mess up 
the signal delay. It is the best “Time Nut” approach in that respect. 

Is this the best of the best solution? Nope, it’s just what 15 minutes of searching on eBay turned up. If I actually was in the market
for something, I’d expect to spend a few hours / days running searches and checking out spec sheets. 

Bob

> On Apr 30, 2020, at 6:20 PM, Forrest Christian (List Account) <lists at packetflux.com> wrote:
> 
> I'll second this thought.
> 
> I've got one of the symmetricom-branded distribution amplifiers in use here
> and it's worked like a charm.   Unfortunately it only works with GPS L1.
> GALILEO seems to be at least mostly in it's passband, GLONASS is not.
> 
> As the bands I've needed have started to increase, I'm now trying to figure
> out how I'm going to bring in a wider swath of bands.   I've been going to
> ask a similar question to the original poster, but with the idea of what
> options are out there for a wider bandwidth.   As a result I'm reading this
> thread with interest since it seems that a lot of the answers would be
> suitable for what I'm hoping to do as well.
> 
> 
> On Thu, Apr 30, 2020 at 2:51 PM Bob kb8tq <kb8tq at n1k.org> wrote:
> 
>> Hi
>> 
>> The original splitters mentioned most certainly do *NOT* short the DC to
>> ground.
>> I have used those splitters for decades to power GPS gear. We have used
>> them
>> in production for runs of thousands of parts ….
>> 
>> Before anybody goes off and spends $1,000 on a splitter, think very hard
>> about
>> what bands you will need it for over the next few years …. also what
>> levels and
>> what antenna voltages. This stuff does change and that’s a lot of money to
>> sink
>> in something that may be a boat anchor in a couple years.
>> 
>> Bob
>> 
>>> On Apr 30, 2020, at 4:36 PM, Arthur Dent <golgarfrincham at gmail.com>
>> wrote:
>>> 
>>> Most of the regular splitters first mentioned are basically transformers
>>> with one side if each winding connected to the case ground so they don’t
>>> work because they short out the 5 VDC on the receiver’s antenna coax. You
>>> have to be aware of the D.C. voltage to power the antenna plus have fake
>>> antenna load resistors on the other ports to prevent error messages.
>>> 
>>> The cheapest non-powered splitter is probably the F connector Steren
>> 4-way
>>> 2.4Ghz splitter made for TV use at $6-$9 each (like eBay # 254474121010).
>>> Their model 201-234 passes 1 port and couples the other  3 ports with
>>> capacitors. I found I could just pry the back cover off the splitter and
>>> solder a 200-330 ohm resistor across each isolated outputs to prevent the
>>> receivers on those ports from giving an open antenna alarm. Those
>> receivers
>>> would still work without the resistors but I couldn’t stand the error
>>> message so I installed the load resistors.
>>> 
>>> Mini-Circuits has made dedicated GPS splitters that have built-in amps to
>>> compensate for losses and the ones I have work quite well. The 5 port one
>>> has a Lucent part number and was made for Telco use with 2 power ports
>> and
>>> 3 isolated ports to which I added 280 ohm resistors. You will find these
>> on
>>> eBay occasionally for far less than the HP versions.  One of my GPS
>>> antennas goes to a WR Incorporated 8-way externally powered splitter with
>>> load resistors built in.
>>> 
>>> So there are a number of options for GPS splitters but they may not be
>> that
>>> common. However, just today I bought another of the 5 port Mini-Circuits
>>> ones on eBay so they do turn up.
>>> 
>>> 
>> https://oi906.photobucket.com/albums/ac262/rjb1998/GPS%20splitters%202_zpspobtp7cf.jpg
>>> 
>>> 
>> https://oi906.photobucket.com/albums/ac262/rjb1998/GPS%20splitters_zpsbitr26xx.jpg
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at lists.febo.com
>>> To unsubscribe, go to
>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>>> and follow the instructions there.
>> 
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com
>> To unsubscribe, go to
>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
>> 
> 
> 
> -- 
> - Forrest
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.




More information about the Time-nuts_lists.febo.com mailing list