The danger I see with this is when your antenna goes bad (and they all do
eventually), your receiver will be hit with the full reflected power of the
PA almost certainly turning it into a smoldering doorstop.
Keith McQueen
801-224-9460
[EMAIL PROTECTED]
-Original Message-
From: Repea
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 b
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
>throug
> 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
> 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
This morning, I checked Motorola Parts and learned that there are 25 of the
12-pin Micor/Mitrek male plugs, Part Number 0180754A26, on the shelf. MSO
price is $16.29. If you are thinking about making your own test cables for
a Mitrek or Motran/Motrac station, don't think about it much more or you
An isolator wont cause intermod, but it may cause harmonics. Commercial
installations usually use either a harmonic filter and 3db hybrid coupler,
or a special type of band pass cavity to couple the output from the isolator
to the feed line. (This info from an RX TX application note on transmitter
Ron,
An isolator is, by definition, a non-linear device- that's how it works.
And that is why it should always be followed by either a low-pass filter or
a notch filter, to remove the second harmonic that is sometimes generated by
its nonlinearity.
The primary purpose of an isolator- which is sim
It's not so much that isolators cause intermod. They generate
harmonics. For this reason, an isolator is always followed by a
bandpass or low pass filter in commercial applications where good
engineering practice is followed.
See:
http://www.emrcorp.com/techinfo/1/pdf/rf_isolators(1-14).pdf
I am not sure why an isolator would cause intermod. Usually there are not
active or non-linear components in them and they are often used to prevent
intermod by preventing outside signals from coming in thru the feedline into
the transmitter.
In the past commerical sites would often require an
> 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 usi
I got your post before, and since then I have acquired a 2m circulator, and
a 50 ohm dummy load for an antenna. My network analyzer says that it does
exhibit the 30db isolation that I'm looking for.. I can insure that the
isolator sees that load with a 2m antenna tuner which I already have, or a
cu
cruizzer77 wrote:
> Hi
>
> This was asked before, but did anyone ever find a source for a 1100S
> service manual?
http://www.repeater-builder.com/ifr/IFR1100.pdf
Kevin Custer
> 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 isolatio
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 rec
Martin,
The last one that sold on eBut made a mint for the seller, I think it went
for over $300.00! The problem after that is all they do is convert it to a
pdf file and sell it on eBut also! I have a CE 4000 manual I recently had
copied for a friend with a couple extra copies made, it was chea
Hi
This was asked before, but did anyone ever find a source for a 1100S
service manual? There seem to be lots of people in need of one, but
none around.
- The one on the repeater-builder website is unfortunately definitely
for the 1000S model
- I have spent a lot of time using Google but no re
Nothing like spending $200 to fix a $2 problem.
Go to www.mouser.com and search for L4940V12. The drop out voltage at
a half amp is 0.2 volts. This means you just need to supply 12.2
volts or higher to get regulated 12.0 volts to your controller.
Dwayne Kincaid
WD8OYG
>
> Thanks, that does so
Hi Bob,
I have had many of these 80 & 100A supplies and what you are experanceing is
several of the supplies are not in sync. Go to the Samlex web site and down
load the manual and it will walk you through the process.
Mike Mullarkey (K7PFJ)
_
From: Repeater-Builder@yahoog
Ron,
Good point.
In my case the voltage measurements were made at the load terminals on the rear
panel of the Samlex SEC-100BRM.
Doug
- Original Message -
From: Ron Wright
To: Repeater-Builder@yahoogroups.com
Sent: Monday, October 22, 2007 5:12 AM
Subject: Re: Re: [Repeate
I have the Mot test set with both Micor and Mitrek cables. I bought at hamfest
for $40.
I would suggest this approach. Also E-bay, the 24/7 hamfest is a good start.
73, ron, n9ee/r
>From: Mike Morris WA6ILQ <[EMAIL PROTECTED]>
>Date: 2007/10/21 Sun PM 08:44:02 CDT
>To: Repeater-Builder@yaho
One note on voltage drop.
Where was the voltage being measured? It should be at the supply, not at the
load. High currents will show drop due to IR losses at the load even with #10
or larger wire.
I have a Samlex SEC1223. When I first got it I did some load test with 4 3 Ohm
100 W resistors
I just read that manual. Seems each supply is adjusted
to 14.2V and should have 1% regulation. They do seem
to be very solidly hard-wired in parallel, but some
kind of jumper is used between all the modules in an
attempt to better share the current.
I hope their other supplies have a similar 1%
re
Thanks, that does sound like the unit that my friend
is using. I wasn't sure what they did to sum the
outputs, and I didn't know it had BB capability. I'd
think the voltage drop would be somewhat constant once
some load current was drawn.
My own repeater needs at least 14.0 Volts because I'm
using
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