"Ian Jackson" wrote in message
...
In message , JB
writes

"JIMMIE" wrote in message
...
On Aug 20, 11:46 am, "Robert11" wrote:
Hi,

Just an elderly sw listener from the old days.
Not very sharp with antenna theory, frankly.

Anyway, would be most grateful for any thoughts on the following,
please:

Have 2 scanners working off of a single Scantenna antenna.
I now switch the Scanners via a good quality pushbutton switch which
supposedly is suited for the vhf/uhf range.
Seems to work fine.

Also have a hardware hf receiver, with its own antenna.

Thinking of getting a new "toy," perhaps a WinRadio SDR receiver.

Here's where the fun starts:

It only has a single antenna input, even though it has vhf/uhf
capabilities.

They want you, apparently, to buy one of their Combiners for $ 200.
Ugh.

Take a look at: http://www.winradio.com/home/acd-1800.htm

Question 1:
Anything "better," or cheaper ?

I guess I will be forced to set up some kind of switch matrix, even if
I
do
use their Combiner.

Question 2:
But, the following problem arises, no matter how I do it.

The HF input, as well as the UHF/VHF input will at all times be
"seeing"
the
turned off hardware HF receiver (when using the SDR PC receiver) as
well
as
the turned off hardware scanner input (when using the SDR PC receiver)

In other words, each input to the combiner would be fed by a "T" where
the
run to the hardware HF Receiver is tapped off to the Combiner. And the
run
to the hardware Scanner is also tapped off via a "T" to the vhf/uhf
input
of the Combiner.

From looking at the link above for the Combiner, and its specs, do you
think
there will be any "meaningful" loss at the SDR PC receiver if I use it,
and
it sees these not-in-use inputs also ?

And the other way around, I guess. If I am not using the PC SDR, will
my
regular Scanner or hardware HF receiver suffer any from having the
Combiner
in place ?

Tried to explain this as clearly as I could, but if confusing, will try
harder if you ask for any clarifications.

Any other way(s) of doing all of this, that would be too complicated or
expensive, perhaps ?

Thanks,
Bob

Have you ever thought of using a patch panel. Use TV F female
conectors on the panel and and push on F connectors on the patch
cables. This will allow yo to connect any rx to any ant.

Jimmie

A vhf/uhf TV splitter would do fine for the VHF/UHF energy. I wouldn't
be
too concerned about signal loss on HF as much and wouldn't worry about T
connectors. The noise is usually high enough not to worry about losing
some. The TV splitter won't pass the HF but it may load it so you may
need a
combiner. The ones made for ham radios would be less than half the cost
for
better than 40 db of isolation. Plenty enough for what you are doing.
Check the specs for your use.

Most TV splitters (those used for cable TV) are specced between 5 to
1000MHz. [They need to pass the return path signals between 5 and
30/40/50MHz.] They obviously provide full throughput down to 5MHz, and
are probably OK to around 2MHz.

Although they are 75 ohm devices, they should work OK where the
impedance is 50 ohms (which, in the case of SW receivers, is very, very
nominal). At HF, their insertion loss is around 3.3dB for a 2-way, 6.5dB
for 4-way, and 10dB for an 8-way.
--
Ian

There is no penalty for going 75 ohm to receivers. In fact, the TV antenna
might do better than a lower placed scanner antenna. Even though the
polarization is wrong, the height makes up for it.

Extra plumbing adds up to loss though. You might find the switches better
to your liking after all.

Another way is BNC connectors and swap things around at will. This
eliminates all unnecessary losses in the system. We always seem to wind up
looking for a better signal without leaving the chair and climbing the roof.