Topband: Receive Splitter or Not?

[Pete Smith]

At 10:32 PM 3/23/2009, K2HN wrote:
>Hello All,
>When bringing in a receive antenna to two receivers is it necessary to 
>have some kind of splitter with isolation?  I just built a box with a T 
>configuration using rca jacks.  I've looked around some and can't seem to 
>come up with a splitter other than one made by Diamond (SS500) and noone 
>I've tried carries it.

It depends ... (helpful answer, right?).  For example, I have had various 
SDRs connected to the RX antenna loop on my two transceivers.  One of them 
did not load the RX inputs at all, while my current one (an SDR-IQ) cost 
several S-units in sensitivity.

A passive splitter will cost you 3 dB minimum - typical 3.5 or so - 
MiniCircuits makes a number of them for HF at a cost of around US$35.  See: 
<http://www.minicircuits.com/products/splitters_main.html>

A better solution may be in the offing - Clifton Laboratories (K8ZOA) has 
an active multi-coupler kit in the works that will feed 4 or 8 outputs with 
zero gain or loss.  I'm not sure how close it is to ready, but you might 
contact Jack.  His web page also has a lot of good info on splitters he has 
tested <http://www.cliftonlaboratories.com/>.  It is a very hard web site 
to navigate, but you can use Google to find things - for example, entering 
"site:cliftonlaboratories.com splitter" (without the quotes) as the search 
term on Google will return all references to "splitter" on the Clifton Labs 
site.

73, Pete N4ZR