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Rob[_8_] · January 5th 13, 08:39 AM posted to rec.radio.amateur.homebrew

Channel Jumper wrote:

Ralph Mowery;800305 Wrote:
"Rob" wrote in message
...-
Channel Jumper wrote:-

Maybe I am out of line here, but what you are asking is dumb.

Diplexers / Duplexers - what ever you want to call them are by nature
only about 50% efficient.
This means that you are throwing away half of your transmitted power
and
half of your capiable receive in the diplexer.. DUMB!-

It is not the diplexer that is dumb, it is your remark that is dumb.-

Most of CJ's remarks are that way. I doubt he has ever measured or
checked
on the splitters. I have and they are usually less than a half of a DB
loss
in them. I am thinking more like a .3 or so of a db loss, but it has
been a
while. Anyway from the best I could tell, it met the spec on the case
of
the splitter. That was with a HP 8924C test set.

Now I know I am dealing with a CB'r

You cannot use a splitter to connect two antenna's together, and a
splitter is not a diplexer.
Even if all you are going to do is use the antenna's for receive only,
you will still run into problems..
If it was a television antenna - we use a con - joiner - it basically
isolates each antenna from each other, is real good for isolation to
prevent multipath, but again, you throw away half of the signal in the
Con - Joiner.

A splitter by nature is wasteful, a 2 way splitter should be unilateral,
each port receives 50% of the signal.
BUT
When you advance to a 3 way splitter, they are not unilateral.
Unless it is a expensive splitter, you usually end up with one port
having about 45% of the signal and the other two sharing the remaining
25% / 30% - between the two remaining ports.
This is the problem I deal with most often with reception issues.

The op buys a splitter, then figures that the television reduces the
amount of received antenna power and so they buy a distribution
amplifier and they figure that if they amplify the signal it will get
better.
The problem being that you not only amplify the signal, you also amplify
the noise, plus the amplifier makes some of its own noise.

So we steer them towards a mast head pre amplifier and it solves some
problems but not all.
If the antenna is not aimed at the strongest part of the signal - we get
little or not reception, or the reception we do get with digital signals
is sometimes corrupted by radio waves arriving at the antenna at
different times.

I've already explained dipole antenna's - which are a balanced antenna,
or a vertical antenna.. So there isn't much of anything else to say
except good bye on this one.

A Diplexer filters out the other frequency signal - and con - joins the
two antenna's together on one feed line. Or makes believe to the
receiver that there is two seperate antenna's, or keeps the rf out of
the other side of the transceiver on a dual band transceiver.

Why are you posting all this irrelevant crap?

When it is not clear to you that there is a big difference in operation
between a diplexer and a splitter, why bother?