[ICOM] IC-756pro RX ANT switching

[Adam Farson]

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
> > >
> > ----
> > 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/
> >
> >
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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/
>
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>
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> Icom FAQ: http://www.qsl.net/icom/
>


----
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/



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