[time-nuts] 58536A splitter and 9390-6000 GPS

[Robert Watzlavick]

I received my Symmetricom 58536A GPS antenna splitter today (new from 
eBay) and did some testing with my Datum 9390-6000, Datum TS2100, and 
Thunderbolt.  The Thunderbolt and TS2100 work fine with the splitter but 
the 9390 has some interesting behavior with the splitter.  If the 9390 
is connected by itself to the splitter, it doesn't report any 
satellites.  However, if I then connect either of the other two 
receivers (Thunderbolt or TS2100) to the splitter, the 9390 will start 
picking up satellites.  Then, if I disconnect the other receivers and 
leave the 9390 connected by itself, it continues to work.  I tested this 
several times and it seems to be repeatable behavior.  So as long as a 
different receiver has been connected to the splitter at least once, the 
9390 works with it.

I'm thinking the initial surge of connecting the 9390 to the splitter is 
causing a momentary overcurrent which shuts down the antenna supply.  In 
the "failure" case, the voltage measured (with a T) at the splitter from 
the 9390 is 0V.  In the "working after a different receiver has been 
connected" case, I measure 4.3V.  The other two receivers output 5V with 
no load and about 4.6V under load connected to the splitter.

Has anybody seen this before?  The antenna is a Symmetricom AT575 type 
antenna.

-Bob