[ICOM] Query.

[Mort Arditti]

Jay,
The intermodulation issue is indeed a problem in any RF rich environment.
I live in Los Angeles and have a Winradio 1550 broad band receiver. The
problem is most severe from approximately 50 to 200 MHz.
The solution was to use an external high pass filter. The filter is a 
simple, passive
3 section pi with 250 MHz corner frequency. It has BNC connectors and
plugs directly at the antenna input of the 1550. It worked very well. The 
fact that it is
external, makes it somewhat inconvenient. One of these day, I plan to modify 
the
filter to include  various band pass characteristics with pin diode 
switching.
At these frequencies, use surface mount components.  I made a 'crude' 
printed
circuit board using a Dremel tool with a very fine bit and magnifying 
glass..
I hope this helps,

Mort,
KB6BSN
----- Original Message ----- 
From: "Jay Eimer" <ad5pe at familynet.net>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Sent: Sunday, October 02, 2005 7:56 PM
Subject: RE: [ICOM] Query.


But Mac, not all DC to Daylight rigs have these problems, requiring filters
that significantly increase the cost of the rig to make it usable.

I too live in a VERY RF rich environment.  I had for several years a Yaesu
FT-2600 2m mobile (with receive from 137-174MHz).  My scanner absolutely
goes nuts with intermod driving past the local hospital.  So does my
friend's IC-2100H.  But my -2600 is silent.

And it was a cheaper rig than the 2100 Icom when new.  I would say the
suggestion that a filter is necessary is a pretty strong NEGATIVE
endorsement, unless you live in a very RF quiet area.

My 2¢
Jay
AD5PE

-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of D C *Mac* Macdonald
Sent: Sunday, October 02, 2005 17:40
To: icom at mailman.qth.net
Subject: RE: [ICOM] Query.

G'day, Mike.

I believe that  ANY  extended coverage rig is going to need filters.  If you
invited DC to daylight in, you need to be prepared to have just that.  The
"old" Icom rigs that covered just the 2 meter ham band were far better than
other rigs of the time for rejecting the garbage.  This is simply impossible
with the wide coverage of today's rigs, no matter who builds them.

My opinion, and it's worth what you paid for it!

(;-p)

Mac, K2GKK/5

p.s.  I have been out of computer/Internet access (willingly) until this
afternoon.

p.p.s.  Yes, I use the filters and for about $65, they  REALLY  work.  You
only lose the freqs between 152 to 154 and 155-157 or thereabouts.
You don't actually lose them, but they are highly attenuated.  I can still
hear local cops, etc. in the
158-159 MHz range, but they are definitely weaker than without the I.C.E.
filters.  There is no noticable effect on NOAA weather radio stations.



----Original Message Follows----
From: "Michael P. Olbrisch" <mike2004 at elp.rr.com>
Reply-To: ICOM Reflector <icom at mailman.qth.net>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Subject: RE: [ICOM] Query.
Date: Sun, 2 Oct 2005 22:26:45 -0000


 > -----Original Message-----
 > From: icom-bounces at mailman.qth.net
 > [mailto:icom-bounces at mailman.qth.net] On Behalf Of D C *Mac* Macdonald  >
Sent: Sunday, October 02, 2005 7:34 PM  > To: icom at mailman.qth.net  >
Subject: RE: [ICOM] Query.
 >
 > I like my 2 2710s and 1 2720.

A good enough endorsement, one line - thank you.

 > If you are subject
 > to high RF density, the notch filters by I.C.E. help  > greatly.  Very
low loss on ham VHF and UHF freqs,  > maybe .2 dB at most.  The rejection is
at 153 and  > 156 MHz;  two notch filters at 153 and one at 156.
 > Virtually nary a peep on 2m when driving past the  > downtown Oklahoma
City area on I-40, a true IM  > alley.

But this part sounds like an endorsement for FILTERS.  I am guessing you use
these filters?

Reading into it sorta backwards, it sounds like the 2720 may have serious
problems WITHOUT the filters.  A lot of words about what I might want to add
in order to fix a problem?  Can you tell me - is the 2720 worth considering
without adding filters?  If not, I will continue to shop for a dual-bander.

Thanks - you are the only reply I got all weekend.

Mike.


----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net Icom Users
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----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/