[ICOM] IC-756pro RX ANT switching

[Jerry K3BZ]

Good idea, I'll check out the KD9SV . Too bad ICOM (and others) don't add a
paragraph to their manual saying what you said. That would be real
helpful... but maybe too much to hope for.

73,  Jerry K3BZ

----- Original Message ----- 
From: "Adam Farson" <farson at shaw.ca>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Sent: Sunday, January 15, 2006 4:06 PM
Subject: RE: [ICOM] IC-756pro RX ANT switching


> Hi Jerry,
>
> The varistor protects the RX-ANT input from excessive voltage to some
> degree. I would recommend an external switch such as the KD9SV Front-End
> Saver when using a separate receiving antenna. It is possible that Icom
> eliminated the fuse in the Pro3 because an external switch offers much
> better protection, and is not "consumable".
>
> http://www.radio-ware.com/ scroll down to KD9SV
>
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ
>
>
> -----Original Message-----
> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
On
> Behalf Of Jerry K3BZ
> Sent: 15 January 2006 12:56
> To: ICOM Reflector
> Subject: Re: [ICOM] IC-756pro RX ANT switching
>
> Thanks, Adam. What is the purpose of that varistor?  In the Pro3, will it
> provide alone the same protection the fuse does in the Pro2?  I'm a bit
> concerned about that fuse... what does it take to "blow" it?  And since it
> sounds like such a giant hassle to replace it, is there anything that can
be
> placed in the external antenna line to "protect" the fuse? The apparent
> necessity for concern if one is planning to use a separate Rx antenna
makes
> this a very interesting subject, and I'd like to get all the info I can on
> it.
> 73, Jerry K3BZ
>
> ----- Original Message -----
> From: "Adam Farson" <farson at shaw.ca>
> To: "'ICOM Reflector'" <icom at mailman.qth.net>
> Sent: Sunday, January 15, 2006 1:16 PM
> Subject: RE: [ICOM] IC-756pro RX ANT switching
>
>
> > Hi Jerry,
> >
> > The Pro2 still has the fuse; on the Pro3, the fuse was eliminated, but
the
> > varistor across the RX-ANT socket has been retained.
> >
> > Cheers for now, 73,
> > Adam VA7OJ/AB4OJ
> >
> >
> > -----Original Message-----
> > From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
> On
> > Behalf Of Jerry K3BZ
> > Sent: 15 January 2006 10:00
> > To: ICOM Reflector
> > Subject: Re: [ICOM] IC-756pro RX ANT switching
> >
> > Is this procedure also good for the Pro2 and Pro3 ?
> >
> > 73, Jerry K3BZ
> >
> > ----- Original Message -----
> > From: "Adam Farson" <farson at shaw.ca>
> > To: "'ICOM Reflector'" <icom at mailman.qth.net>
> > Sent: Sunday, January 15, 2006 12:30 PM
> > Subject: RE: [ICOM] IC-756pro RX ANT switching
> >
> >
> > > Hi Dave,
> > >
> > > The fuse (DS111) is soldered in place. You can check its continuity by
> > > placing one meter probe on the centre pin of the RX-ANT jack, and the
> > other
> > > on one of the pads of L112 (RF UNIT board). I assume you have the
> service
> > > manual.
> > >
> > > To change out DS111, you will need to lift out the RF UNIT board.
> > >
> > > Cheers for now, 73,
> > > Adam VA7OJ/AB4OJ
> > >
> > >
> > > -----Original Message-----
> > > From: icom-bounces at mailman.qth.net
[mailto:icom-bounces at mailman.qth.net]
> > On
> > > Behalf Of Dave G4GED
> > > Sent: 15 January 2006 05:58
> > > To: ICOM Reflector
> > > Subject: Re: [ICOM] IC-756pro RX ANT switching
> > >
> > > Hi Adam
> > > mni tnx for your reply.
> > > Well, when I switch to 1/R or 2/R, with a known good RX antenna
plugged
> > into
> > > the RX ANT port, I hear absolutely nothing !
> > > I've looked at the Manual and opened up the radio and found that RF
fuse
> > > (lamp) but cant find any way of getting my test probs onto one of
those
> > tiny
> > > components in order to test the fuse's continuity.
> > > I was hoping it was unpluggable but it appears to be soldered. I
darent
> > give
> > > it a pull to try incase I cause further damage.
> > > Could you please just confirm whether it is soldered in or not or any
> way
> > of
> > > testing it's continuity in situ?
> > >
> > > Tnx agn 73 Dave G4GED
> > >
> > > ----- Original Message -----
> > > From: "Adam Farson" <farson at shaw.ca>
> > > To: "'ICOM Reflector'" <icom at mailman.qth.net>
> > > Sent: Sunday, January 15, 2006 8:30 AM
> > > Subject: RE: [ICOM] IC-756pro RX ANT switching
> > >
> > >
> > > > Hi Dave,
> > > >
> > > > 1/R and 2/R switch the receive RF signal path from ANT1 or ANT2 to
the
> > > > RX-ANT input. If the input is still "a wee bit deef" (like auld Mrs.
> > > > McGregor), the RF fuse DS111 (Part No.HRS-4160A) on the RF UNIT
board
> > may
> > > > have gone open. (IC-756Pro Service Manual, p. 10-8).
> > > >
> > > > You can download the IC-756Pro service manual from Marcucci, mods.dk
> or
> > > > http://www.qsl.net/icom/
> > > >
> > > > Cheers for now, 73,
> > > > Adam VA7OJ/AB4OJ
> > > >
> > > ----
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> >
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>
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>