DePolo
Sent: Tuesday, October 23, 2007 6:43 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: RE: [Repeater-Builder] Re: duplexer isolation and reciever
noise budget
If I do two antennas, the best I can do is about 30db
isolation (30ft separation, 6db multi-bay folded dipole
antenna
On Oct 24, 2007, at 12:37 AM, John Barrett wrote:
Re splitting the simplex: a circulator with the radio hooked to the
input, the transmit chain on the standard output, and the receive
chain feeding the load port is what I was thinking – a relay would
do the job just as well, but would
OK - Here are my requirements for the transmit chain. minimal
physical space and minimal insertion loss :-) (ok - too
bloody obvious) Tuning simplicity is also a factor. I'm
combining 3 transmitters at 144.39, 145.05 +/- 0.04 and 145.25
snip
Can you list out some of the other options that
, ron, n9ee/r
From: Jim [EMAIL PROTECTED]
Date: 2007/10/24 Wed AM 09:17:56 CDT
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Re: duplexer isolation and reciever noise
budget
OK - Here are my requirements for the transmit chain. minimal
physical
Sent: Tuesday, October 23, 2007 6:43 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: RE: [Repeater-Builder] Re: duplexer isolation and
reciever
noise budget
If I do two antennas, the best I can do is about 30db
isolation (30ft separation, 6db multi-bay folded dipole
antenna
At 09:51 AM 10/24/2007, you wrote:
OK, I have to comment,
An isolator/circulator should not be used in a duplexer at the
antenna connector when there are other strong signals floating
around the air that can get into the isolator.
---Uh...a couple of things here:
1) Did I miss something
Replace the duplexers antenna tee with a circulator. Tune the
circulator as follows: Port A to B to pass TX frequency, port B to C
to pass RX frequency. Port A to Port C isolation should be in the 20dB
range or better and it still protects the transmitter and helps with
mixing. RF from the antenna
: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Ken Arck
Sent: Wednesday, October 24, 2007 12:04 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] Re: duplexer isolation and reciever noise
budget
At 09:51 AM 10/24/2007, you wrote:
OK, I have to comment
Ron Wright wrote:
Also if packet on VHF and repeater on UHF a simple crossband coupler
and dual-band antenna will simplify things.
73, ron, n9ee/r
Yes-greatly!
--
Jim Barbour
WD8CHL
145.25 can be a real pain. We have a repeater on that frequency. It is CATV
channel E. We always have leaks from the cable rendering the repeater
useless in some areas until a call is made to the CATV plant. They go out
and tighten the screws on an amplifier (left loose by the last tech working
Again, the circulator will produce intermod when external strong
signals enter the antenna port when used as a switch for the duplexer
and there is transmitter power also going through it. 50 Watts or
47dBm to -116dBm receiver sensitivity is 163dBm dynamic range. The
device is not linear
At 10/24/2007 19:46, you wrote:
145.25 can be a real pain. We have a repeater on that frequency. It is CATV
channel E. We always have leaks from the cable rendering the repeater
useless in some areas until a call is made to the CATV plant. They go out
and tighten the screws on an amplifier (left
[EMAIL PROTECTED]
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of John Barrett
Sent: Monday, October 22, 2007 7:47 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: RE: [Repeater-Builder] Re: duplexer isolation and reciever
noise budget
??
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Jeff DePolo
Sent: Monday, October 22, 2007 9:41 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: RE: [Repeater-Builder] Re: duplexer isolation and reciever
noise budget
Commercial installations
OK - Here are my requirements for the transmit chain. minimal
physical space and minimal insertion loss :-) (ok - too
bloody obvious) Tuning simplicity is also a factor. I'm
combining 3 transmitters at 144.39, 145.05 +/- 0.04 and 145.25
Before we get to what hardware to use, we still need
-Builder] Re: duplexer isolation and reciever
noise budget
OK - Here are my requirements for the transmit chain. minimal
physical space and minimal insertion loss :-) (ok - too
bloody obvious) Tuning simplicity is also a factor. I'm
combining 3 transmitters at 144.39, 145.05 +/- 0.04
If I do two antennas, the best I can do is about 30db
isolation (30ft separation, 6db multi-bay folded dipole
antenna on bottom, 9db 2m/440 base station antenna on top),
If you can get 30 feet of separation, you'll get more than 30 dB of
isolation. More like 50 dB on VHF, 60 dB or more on
Time to reopen this subject just a little !!
I'm currently looking at Icom V-8000 radios for the simplex and repeater
radios (0.15uV sensitivity (-123dbm) and 75db spurious/image rejection)
The most any transmitter in the system will ever be running is 50 watts
(+47dbm)
Transmit and
Transmit and receive paths will be separate with 30db of
isolation (either split antennas, or a 30db isolation
circulator just before the feed to the antenna)
I posted a followup to one of your previous messages regarding using
isolators as a makeshift way of getting more Tx to Rx isolation,
: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Jeff DePolo
Sent: Monday, October 22, 2007 3:11 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Re: duplexer isolation and reciever
noise budget
Transmit and receive paths will be separate with 30db
This isn't guessing - its called RESEARCH
When I said guessing, I was talking about quantifying the performance of
your radios rather than guessing how much isolation you need. In other
words, make measurements to actually determine how much noise supression and
carrier attenuation you need
To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com
yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Re: duplexer isolation and reciever
noise budget
This isn't guessing - its called RESEARCH
When I said guessing, I was talking about quantifying the performance of
your radios rather
I am not sure why an isolator would cause intermod. Usually
there are not active or non-linear components in them
An isolator IS a non-linear device.
and
they are often used to prevent intermod by preventing outside
signals from coming in thru the feedline into the transmitter.
As a
An isolator wont cause intermod, but it may cause harmonics.
How so? What phenomenon occurs in a ferrite circulator that creates
harmonics but won't generate IMD?
Commercial installations usually use either a harmonic filter
and 3db hybrid coupler, or a special type of band pass cavity
At 07:41 PM 10/22/07, you wrote:
I'm proposing a novel application of the circulator (an
isolator without the dummy load on one port)..
Yes, I know what you're trying to do, and it's nothing new. UHF Micor
mobiles have an isolator in the antenna network that routes received RF
through the
On Oct 22, 2007, at 7:19 PM, Ron Wright wrote:
I am not sure why an isolator would cause intermod.
The fact that they create harmonics unless filtering is done
downstream of the output port going toward the antenna, means that
the opportunities for external mixing are increased greatly by
: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of John Barrett
Sent: Monday, October 22, 2007 7:47 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: RE: [Repeater-Builder] Re: duplexer isolation and reciever
noise budget
An isolator wont cause intermod, but it may
@yahoogroups.com
Subject: [Repeater-Builder] Re: duplexer isolation and reciever noise budget
Before I give you an answer I'd want to know where the repeater
is going to be placed. Operation in the 146 and higher portion of
the band is going to be a heck of a lot easier than a repeater
in the 145
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