[time-nuts] Isolation and insertion loss of Minicircuits splitters

[Charles Steinmetz]

Dave wrote:

>Some time ago I mentioned I'd bought a couple of Minicircuits 16-way power
>splitters with the intention of making a 10 MHz distribution amplifier
>      *   *   *
>Here are the ISOLATION results.
>      *   *   *
>CONCLUSIONS
>      *   *   *
>6) Despite the Minicircuits data sheets imply there are two isolation
>figures for "adjacent" and "opposite", I measure 3 different values for
>each splitter, not 2.

As I posted on January 8, there are actually four different cases in 
a 16-way splitter.  You have found that the port-to-port isolation of 
two of the four cases are indistinguishable in practice in the MCL splitters.

The datasheets do not imply that there are only the two cases.  MCL 
simply specified the best ("adjacent") and worst ("opposite") cases, 
without specifying the intermediate cases.

Good luck with your DA system.  For simple distribution of a 
frequency standard, it should work very well.  I use a similar system 
with a suitable ULN/HDR preamp to feed antennas to multiple 
receivers, and it performs superbly.

For an output at the typical instrumentation level of 1Vrms (13dBm), 
you will need an amplifier with a 50 ohm output impedance that puts 
out ~26dBm (=400mW, =4.5Vrms, =6.3Vpk, =12.6Vp-p).  The peak output 
current is >125mA.  If you are going to realize the 50 ohm output 
impedance with a low impedance amplifier and a 50 ohm buildout 
resistor for back-termination, the amplifier will need to put out 
over 25Vp-p into 100 ohms.  If you want the outputs at the same level 
as the original source, the amplifier will need to have a bit more 
than 12dB of gain.  Have you decided what you are going to use?

Best regards,

Charles