Amateur Radio - IC-207H 2m power module repair

The Icom IC-207H is a nice radio.  I was fortunate enough to obtain one from a friend.  It was used hard and its beginning to show.  However, as a mobile rig goes, its a small tough package.  The problem is that I've begun receiving reports that my signal is breaking up when the radio gets hot.

A fellow ham also has a IC-207H and recommended to inspect the SC-1091 VHF power module.  Apparently this module has a ceramic substrate and will form cracks due to uneven heating.  He recommended bridging the cracks with solder and a thin wire.

Since the IC-207H dual band mobile is a fairly simple rig, disassembly is easy.  First remove the head unit and the screws that hold the head connector on the main unit.  Remove the four bottom case screws and then remove all the screws from the main board and the two retaining screws from the power modules.  Unsolder the antenna connector and slip the board out.

The 2 meter power module is the one with fewer wires coming out of it.  (The 70cm module is actually sealed and you can't get into it anyway.)  Unsolder the 2 meter power module and GENTLY pry the black cover off.  Its on there pretty good, so just work it off a little at a time.  Don't break the ceramic substrate.  Once the cover is off inspect the ceramic for hairline cracks.  Use a soldering iron with HIGH heat >40w and bridge any gaps in the traces with some light wire and good solder.  The module dissipates heat quickly, don't use too much solder or you'll just have a blob.

You can see the hairline crack on this module and then how it was repaired.  You have to look really hard to see the crack.  Its in the center of the board.

Forgive the globbly solder, its on there good, but its hard to get it hot enough to melt uniformly.  I didn't want to make it worse by overheating the ceramic in one spot with the soldering iron.

When re-assembling grind the little clip areas off the inside of the 2 meter power module cover.  This will reduce the stress on the ceramic during re-assembly.  After this repair procedure the radio works great.