[Icom] Re: IC 746 problem

Fri, 15 Mar 2002 21:18:33 -0000

On 15 Mar 2002 at 12:01, [email protected] wrote:

> Message: 2
> From: "tom johnson" <[email protected]>
> To: "ICOM Reflector" <[email protected]>
> Date: Fri, 15 Mar 2002 06:14:51 -0000
> Subject: [Icom] IC 746 problem
> Reply-To: [email protected]
> 
> I asked this question earlier this week and several of you said it is
> normal for the 746, but I would like some second opinions.....
> 
> Recently, or at least it's gotten worse recently, my receive has begun
> cutting out, on strong signals when they end abruptly. The delay seems
> to be about a seconds duration usually, but has been longer than that.
> This seems to be worse on RTTY, and has gotten so bad now that it is
> beginning to cut out in the middle of a transmission, and leaves gaps
> in the text. It is almost like the squelch setting is too tight
> causing the signal to drop out if the signal drops slightly. The
> squelch setting has no effect on this, and in fact, I went into the
> menu and turned the squelch off, with no change.
> 
> It does it periodically on SSB, but is not nearly so bad as it is on
> RTTY. My first thought was the MTTY program, but since it is doing it
> too on SSB, I don't think that is the problem.
> 
> Last weekend, I installed a 500 Kc filter in the 9 Mc filter slot, but
> have made no other changes. Truthfully, if this is "normal", I think
> this thing may be for sale shortly.

Hi Tom, I've never experienced the problem you describe with my 746.  Has 
it only started to happen since you installed the 500Hz filter?  If it has, then 
it might be worth checking that you didn't accidentally dislodge any of the 
cables connected to the PCB the filter plugs into when you did the 
installation.  It sounds like you've got a bad connection somewhere, possibly 
on the PCB itself.

Over the last several weeks I've been trying all sorts of different InRad 
9MHz filters in my 746, so the rig has been opened up and filters plugged in 
and out quite a few times but so far there have been no obvious side-effects 
from all the fiddling around.

Can you cause the loss of signal by tapping the outside of the radio?  You 
could try operating the radio with the bottom cover off and seeing whether a 
*gentle* tap with the insulated handle of a small screwdriver at various 
places on the PCB causes the problem to occur.  Make very sure that you 
don't damage any of the very small components if you do this.  You could 
also try gently pressing the PCB to flex it in various places.  It might also be 
worth getting an aerosol of freezer spray and seeing whether spraying any 
particular area of the PCB causes the loss of signal.  If you find that one 
area seems to be more prone to vibration, flexing or chilling then that might 
be the place to start looking for dry joints, solder whiskers or broken PCB 
tracks.

I will bear no responsibility for any damage you may cause to your radio by 
doing any of the above.

Good luck,
---
Martin, G0HDB