RadioBanter - View Single Post - RRS - The Topic is Shortwave and the Goal is to Talk About (Write About) Shortwave related things . . .

December 5th 05, 03:21 AM posted to rec.radio.shortwave

In article . com,
wrote:

RHF wrote: snip
So The Question Becomes : Will You Contribute and Post that One
Message a Day or Be One of those to Reply and Comment - - - Will
You ? ? ? - - - It Begins With You - - - Be Their ! ! !
snip --------------------- I am trying to work up my nerve for a
certain on topic flame war over "power dividers", signal spliters,
"passive multiset couplers" or as us engineers like to call them,
"hybrids" and thier possible use in a "normal" SW environment.

It is rather counter intuitive.

I am still trying to find a valid, acceptable "on line" refference
for typical natural HF noise floor. Step one was to get everyone to
agree that a good hybrid only introduces 3+dB of loss. That was way
too much fun.

I think that was me arguing with you on the news group. I just was not
paying attention to the power loss due to the fact that I used the
resistive type in small signal work and just did not pay attention to
that aspect (power lost) of dividers.

The magnetically coupled units were a little over 3dB and the resistive
were a little over 6 dB due to the resistor losses best case(s). The
3dB point being half the power because the source is divided in two.
The resistors used in the "resistive" units burn half the power (again)
in order to cause the impedance thru the splitter to look like 50 ohms
on all ports with the proper source and loads attached otherwise there
would be large reflections. The magnetic coupled units just transfer
the load impedance thru the unit so as long as the source and load
impedances match up that is all that is required. Well, the path
through the windings also is supposed to be the same impedance for
higher frequencies at least.

What is counter intuitive to you about either kind of
splitter/combiner?

On the news group we should take care to reference typical natural HF
noise floor and receiver sensitivity in dBm so the addition of
components like splitters can make sense in an antenna system way.

--
Telamon
Ventura, California