[time-nuts] Component level 1:2 splitter

[randy warner]

Dan,

Thanks for the info. It looks like Mini-Circuits little BP2G IC should work
well enough. 3dB of loss SHOULDN'T bother anything, the Novatel L1 CP
receivers we use here are almost deaf....... So long as the isolation stays
up in the high 20's and I put buffers on all ports I should be OK.

Randy



-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Dan Rae
Sent: Monday, March 10, 2008 3:23 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Component level 1:2 splitter

randy warner wrote:

>Guys,
>
>I need to come up with a 0db little splitter to route 1 antenna into 2 GPS
>receivers. To keep the isolation up I want to use an active splitter
instead
>of a passive one.
>
Randy,
For a long time I used a passive splitter made from a swap meet $1 MCL 
(minicircuits) 1 to 2 GHz splitter / combiner.  Isolation of these is 
good, around 30 dB, and the extra 3 dB loss will not be noticed in the 
majority of cases.  This one had SMAs all round and DC continuity 
through from the A and B ports to the Common.  I blocked one path to DC 
with a 100 pF SM capacitor.  If you need the Rx connected to the blocked 
path to think it is feeding an antenna a series R and L combination with 
a 220 Ohm R will fool the Rx in question.

I really would not think you will need any gain.  For more than two 
receivers though I would recommend the hp / symmetricom (?) 4 and 8 way 
active splitters that can be found on eBay.  If you did want gain there 
are a lot of MMICs that will do the job.

I've given it away a while back so can't give you any further details, 
but for two receivers this worked well for me. For my growing collection 
of gps units here I now need more than two...

Dan




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