Chinese duplexers
 

Geoffrey S. Mendelson wrote:

Allodoxaphobia wrote:

We still don't have a clear description of what the OP is trying to
accomplish.

Take two radios, two j-poles and a lot of coax and make a repeater.
Obviously I will need some sort of controller in between but that's
irrelevant.

I want to place one J-pole (or similar antenna) at one corner of my garden,
and another at the other one (10 meters apart).

One will be used to receive a signal, the other to relay it. They both
will be somewhere on the 144-146mHz band, with the output being a few watts
with a max of 20.

Besides the distance, I was looking for a cheap way of not having
the transmitted signal block the receiver. The duplexer in question
is rated at 75dB isolation with a 3.5mHz split, I can only have .6 mHz.

What I was wondering is that since at a .6mHz split, the isolation will
be a lot less, can I somehow combine the two sides to make a better
filter?

Thanks,

Geoff.


If you have two antennas you don't need a duplexer. Just notch the
transmit from the receive antenna.

Chinese duplexers
 

On 31 Aug 2011 12:41:25 GMT, dave wrote:

Geoffrey S. Mendelson wrote:

Allodoxaphobia wrote:

We still don't have a clear description of what the OP is trying to
accomplish.

Take two radios, two j-poles and a lot of coax and make a repeater.
Obviously I will need some sort of controller in between but that's
irrelevant.

I want to place one J-pole (or similar antenna) at one corner of my garden,
and another at the other one (10 meters apart).

One will be used to receive a signal, the other to relay it. They both
will be somewhere on the 144-146mHz band, with the output being a few watts
with a max of 20.

Besides the distance, I was looking for a cheap way of not having
the transmitted signal block the receiver. The duplexer in question
is rated at 75dB isolation with a 3.5mHz split, I can only have .6 mHz.

What I was wondering is that since at a .6mHz split, the isolation will
be a lot less, can I somehow combine the two sides to make a better
filter?

Thanks,

Geoff.


If you have two antennas you don't need a duplexer. Just notch the
transmit from the receive antenna.
I think that is what he is asking. Can he takes his duplexer and use
it as an extra sharp notch filter for his receiver. One "side" is
already set up for that purpose. He is asking if the "side"
originally intended for the transmitter can be used to further filter
the receiver.

Chinese duplexers
 

On 8/30/2011 5:13 PM, Jim Lux wrote:

What about VoIP using 802.11 as the link. These days, that might be
easier than trying to cobble up a 440 remote link.

Joy!

I am going to sit back and see how this suggestion evolves.

tom
K0TAR

Chinese duplexers
 

tom wrote:

I am going to sit back and see how this suggestion evolves.

Look at SVXLINK. It's an open source package that runs on Linux (and possibly
BSD) that does exactly that.

It includes support for remote receivers (with a voting option), remote
transmitters, and an echolink server.

We plan to use it with hard wired internet links, but who knows, an 802.11
link could work. Unlike the US we are restricted to 100mW EIRP, so no
gain antennas, etc, to make things work better.

Geoff.


--
Geoffrey S. Mendelson N3OWJ/4X1GM
Making your enemy reliant on software you support is the best revenge.

Chinese duplexers
 

Geoffrey S. Mendelson wrote:
We plan to use it with hard wired internet links, but who knows, an 802.11
link could work. Unlike the US we are restricted to 100mW EIRP, so no
gain antennas, etc, to make things work better.

Do you have a transmit ban on 802.11 channels in 4X too?

We as hams in the Netherlands are no longer allowed to transmit above
2400 MHz except to an amateur satellite.

Chinese duplexers
 

Rob wrote:

Do you have a transmit ban on 802.11 channels in 4X too?

We as hams in the Netherlands are no longer allowed to transmit above
2400 MHz except to an amateur satellite.

There is a limit of 100mW EIRP for 2400-2450 mHz for terrestrial use,
with a limit of 100W EIRP to satellites in the 2400-2402 mHz part of the
band. This is from a document on the Ministry of Communicatons website,
dated 1999. It has been unchanged except for the addition of 7.100-7.200 mHz
so they never bothered to update it.

The difference between a 100mW limit and an outright ban in practice is
very little IMHO.

For example, you can turn off encryption and use a WiFi device as a packet
radio, or you can call CQ on your cordless phone. :-(

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Making your enemy reliant on software you support is the best revenge.