I have problem with my 70cm rig, an Icom IC-448. I have used
it for packet radio about ten years (running 24/7) and
suddenly the squelch have stopped working. I have no schematics
but know, from the manual, in what area the squelch circuitry
is and have looked at the voltages there. But I am not that
much wiser from doing so. Pressing the monitor button will
open the squelch after an initial period, acting as if a capacitor
is charging up. But normal squelch does not work at all.

Anyone who have had this problem and found the cure for it?
Anyone who have a schematic?

73 de Lars, sm6rpz

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Lars E. Pettersson | Chalmers University of Technology
| Gothenburg, SWEDEN

On 28 Aug 2003, Lars Petterson wrote:

I have problem with my 70cm rig, an Icom IC-448. I have used
it for packet radio about ten years (running 24/7) and
suddenly the squelch have stopped working. I have no schematics
but know, from the manual, in what area the squelch circuitry
is and have looked at the voltages there. But I am not that
much wiser from doing so. Pressing the monitor button will
open the squelch after an initial period, acting as if a capacitor
is charging up. But normal squelch does not work at all.

Anyone who have had this problem and found the cure for it?
Anyone who have a schematic?

73 de Lars, sm6rpz


I had an IC-28A 2 meter rig do that. It was the squelch control itself
that had gone bad. And it is a real bugger to change due to the place it
is mounted. It can be done though, you will have to contact ICOM to see
if they are still available. I had to replace mine about 5 years ago
after 6 or 8 years of packet service 24/7.
Good luck finding the part.
73 de KE8TQ
Fred

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