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

Hi Robert

As I see it, you are considering a very complex "radio listening system".
Aparently you are considering two or more receivers and two or more
antennas. That will involve lots and lots of compromises.
Is it reasonable for you to insert DC blocks in the antenna connections to
each receiver? If so, connect all the antennas and receivers any way you
want. If you get adequate performance, there will be nothing additional
required. As you experience performance inadequate performance, then, you
can investigate automatic (computer controlled) switching or "combiners".

Jerry KD6JDJ


"Robert11" wrote in message
...
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

Hi Robert

Good to see you on again! Yes quite a lot of endless possibilities!

It all pretty well boils down to how much loss you can "stand". Any
unswitched configuration will lose at least half the signal in a 2 way
split. This probably isnt a big deal at HF (since received noise is
always much greater than the receiver noise floor), but may be "just
enough" to cause problems at VHF+. Physical switches also introduce loss
that varies with quality and operating frequency. One day too you'll
want to have two receivers going concurrently and if you have a switched
config will curse having it that way!

My suggestion? Check that there isnt any DC present on the antenna
terminal of all your radios (that might be used for external preamps
etc) and just hard connect the two scanners to the one antenna. Do some
signal checks on a few known stations and see if you are losing enough
to be troubled.

Do a few diferent evolutions to check the HF radio/antenna in tandam
with the VHF/UHF system and standalone. I would expect problems here as
some VHF/UHF antennas will look like dead shorts at HF.

If you have a signal generator set that up as a beacon in your yard. You
may also be able to hear harmonic content to check up higher. (I often
use the 5th harmonic of my HF radio to freq check my VHF radio, after
having calibrated my HF radio to WWV)

Combiners are often transformers on toroids of varying sizes per
frequency range. VHF+UHF combiners can be made of etched PCB's. You'll
find quite a few designs in Ap Notes by the likes of Motorola if you
look around. This may of course not be an option for you. Single
frequency (+ odd multiple) splitters are much easier to build. All you
need is coax!

In the end I would hope you can get away with low pass filter on the HF
antenna (an old CB TX filter will do) and a high pass filter on the
Scantenna (maybe a TVI filter meant for 75 ohm TV installs), a broadband
combiner/splitter and 4 outputs, one to each RX.. You may even be able
to use a CATV splitter. They supposedly work down to 5MHz nowadays (for
cable internet upload) Thats about the cheapest I can think of, but of
course there will be some loss. I dont think CATV splitters go past
about 1GHz for example.

As to your off vs on Q2. In a theroetical world your splitter device
would have a specfic Z and for max power transfer your receivers would
have the same. It never happens that way in real life though. In your
case too you are receiving only so the problems become a lot simpler!
Yes you would lsoe a proportion of the signal. Only you can determine if
that is significant.

And to "meaningful" loss? Try it! Changing your antenna height may even
negate all the loss you are concerned about. Thicker coax may be an
option too if you are interested in a lot of distance UHF work. Then
again if you are that interested a preamp may also be in order!

Apologies for not being specific!

Cheers Bob W5/VK2YQA


Robert11 wrote:
Hi,

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

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

"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.

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

"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.