[Premium-Rx] MULTICOUPLER IP2

[k0dan]

"When people connect such a multicoupler to a large wideband antenna, they
are in for an unpleasant surprise" depending on their environment.

I'm not gonna argue with the and/or comparisons of a $200-$300 multicoupler
to a 4- or 5-thousand unit, but the facts are that the multicoupler which
started this thread (sold, by the way, thanks for the inquiries!) worked
FINE. Granted, it was not installed in Europe, at a Voice Of America site,
etc., etc.

It WAS installed using broadband antennas, in a relatively quiet RF
environment (Missouri, USA), and worked FINE. Never encountered intermod,
distortion, crosstalk, etc. Sometimes the multicoupler was directly on an
antenna, other times it was behind an amateur transceiver's bandpass filter,
it worked FINE.

The key is to ask the question of what application and environment is a
given piece of equipment being used in.

To suggest a blanket condemnation of low-end multicouplers (or anything else
for that matter) is just stereotyping and generalization. On the other hand,
if you're building a multi-receive site which is a 1/2 mile from 100KW
transmitters, you have a different scenario.

Apples and oranges.

Have fun folks...

Dan

----- Original Message -----
From: "Karl-Arne Markström" <sm0aom at telia.com>
To: "Tracey Gardner" <tracey.gardner at talktalk.net>;
<premium-rx at ml.skirrow.org>
Sent: Saturday, April 01, 2006 10:48 AM
Subject: Re: [Premium-Rx] MULTICOUPLER IP2


The low IP2 value (if it is not a misprint) implies that this multicoupler
does not have balanced amplifier stages internally.

When people connect such a multicoupler to a large wideband antenna,
they are in for an unpleasant surprise.

In order to work in the European RF environment, using wideband gain
antennas,
a reasonable IP2 requirement  is + 80 to +85 dBm. This level is
representative for
i.a. the Raven Research and R&S NV-14 multicouplers, and leaves the HF
receiver IP2 as the
dimensioning factor in the system.

73/

Karl-Arne
SM0AOM



----- Original Message -----
From: "Tracey Gardner" <tracey.gardner at talktalk.net>
To: <premium-rx at ml.skirrow.org>
Sent: Saturday, April 01, 2006 6:33 PM
Subject: [Premium-Rx] MULTICOUPLER IP2


> Hi Warren
>
> Take a look at this ARRL article
>
> http://www.arrl.org/tis/info/pdf/020708qex046.pdf
>
> To quote " In modern receivers, IPs may by quite high.
> It is not unusual to see receivers with third-order intercept
> points (IP3s) of +30 dBm (1 W) and second-order intercept
> points (IP2s) of +80 dBm (100 kW).
> IPs form an excellent basis for comparison of receiver
> distortion performance"
>
> Looking at that +42dbm in a multicoupler ain't so hot
>
> Tracey
>
> >
> >> In Europe you would not get very happy with an IP2
> >> of +42dBm
> >
> >  Isn't +42dBMm 15 watts? Do you have more than 15
> > watts of off channel signal into your antenna?
> >
> > Warren
> >
> > --- Clemens Paul <cpaul at gmx.net> wrote:
> >
> >> " 2nd & 3rd Order Intercepts 45 dB & 42 dB " (specs
> >> from
> >> http://www.testequipmentcanada.com/M-50-8.html.)
> >>
> >> In Europe you would not get very happy with an IP2
> >> of +42dBm except you are using
> >> very selective narrow banded antennas or additional
> >> preselection before the coupler.
> >>
> >> Clemens
> >> DL4RAJ