[time-nuts] HP/Symmetricom 58535A and 58536A

[SAIDJACK at aol.com]

Hello Magnus,
 
yes, interestingly enough the units I have seem to have the option to power 
 them through port-1 removed by brute-force: the inductor on all my units 
has  been ripped off the PCB by force!
 
This holds for the 1-2, 1-4, and 1-8 Agilent/Symmetricom splitters I have,  
all of them have this rather rude modification made (and they are all from  
different sources, and vintages).
 
Thus port-1 has no DC load at all, while all the other ports have a DC load 
 to ground for the GPSDO.
 
Maybe this is the problem, I need to see if the Thunderbolt works with or  
without a DC load..
 
I am glad I am not the only one having this issue with the Thunderbolt  
though.
 
One more tidbit on the side: it is not a good idea to mix-and-match GPSDO's 
 that have different antenna voltages (5V and 3.3V for example) on a 
passive,  DC-coupled splitter. This will create a problem. And can also lead to 
some  really interesting results:
 
I have a USB eval board from a Taiwanese company, and noticed that it  
generated a 1PPS without the USB being plugged-in. Very strange.
 
Turns out the board is getting power and running perfectly well from  
another GPSDO connected to the same passive antenna splitter, and being fed  
power from it's own antenna input!!
 
bye,
Said
 
 
 
 
 
 
In a message dated 11/1/2009 03:19:14 Pacific Standard Time,  
magnus at rubidium.dyndns.org writes:


>  The amp is followed by a resistive splitter, and possibly a resistive   
> attenuator (on the 2-port version). Then a cavity filter, then the  
N-Connector,  
> very simple, not much that can go  wrong.

They do have DC load on the non-DC-thru ports.

Check the  open/short status on the thunderbolt. It's very easy to see 
with the  Thunderbolt monitor  program.

Cheers,
Magnus