"Ian Jackson" wrote in message

You missed out step #2, which was to measure the output level of the
splitter alone.

Using your figures, this would have shown a signal loss of 3.625dB (3dB
power split loss and 0.625dB of circuit loss).

When you then added the combiner, you would have 3dB power split loss and
0.625dB of circuit loss, followed by 3db power combine gain and 0.625dB of
circuit loss - so as you measured, a total loss of only 1.25dB.

Despite working in the cable TV industry for 43 years, for some reason
this is an experiment I don't recall ever performing!

Thanks Ian,

Earlier in this thread, I saw what I thought to be an error in some postings
.... about losses in excess of 3dB in the combiner and a conclusion that
stacking results in less signal, which shouldn't be the case. My little
experiment was meant to demonstrate a signal increase from combining
in-phase signals in a passive device. Put another way, I wanted to show
that a 3dB loss is not inherently present in both directions.

You are correct that I did not make the measurement of the output level of
the splitter alone, since it has been made and documented on many occasions.
A real lab experiment would have measured that and the cable losses, too.
(My 35 year-old Jerrold 747 was within easy reach and "close enough.")

It was my intent to show, when two equal signals (presumptive on my part
that the two outputs of a splitter are equal) are combined, that the result
is the addition of the two, minus ohmic and coupling losses, which I think I
did show.

"Sal"