I think this is the 3rd Kenwood 1100u that I've done, and assuredly my last. I didn't keep track of the hours, but I'm sure I have 30-40 in it.
I purchased it on eBay. It arrived with no output tubes; most of the others were weak. One of the OPTs had caught fire and had been replaced by an odd one that was bad, too.
There was a small fire or two below deck. I had to replace a binding strip and a lot of wire. The multi-cap had leaked corrosive goo. All electrolytics were replaced, along with every non-disc coupling cap, safety cap, etc.
Several out-of-spec resistors were replaced as well. I added an adjustable bias control and 10 ohm safety resistors on the cathodes of the 7591s.
I undid some "mods" that a previous owner made, and then modified the headphone circuit slightly. I relubed all of the controls; replaced lamps, etc.
I had a pair of Sansui OPTs from a 1000A - they bolted in place with minimal fuss. They were slightly bigger than the original Kenwoods; they didn't have a 4 ohm tap (which was used for the headphone circuit exclusively). Otherwise, they were a great fit.
I bought some EH 7591s from Jim McShane. Plate voltage on these is 506 VDC! I've got them biased at 22.5 mA which is under the 70% recommended bias setting.
I fired it up and it works. FM MPX needs some adjustment (no surprise) and there is a bit of hum in the AM section to track down, but the AUX sounds glorious.
I think the Sansui iron is an upgrade for this model. If any of the other 1100u's that I worked on sounded this good, I wouldn't have sold them!
I purchased it on eBay. It arrived with no output tubes; most of the others were weak. One of the OPTs had caught fire and had been replaced by an odd one that was bad, too.
There was a small fire or two below deck. I had to replace a binding strip and a lot of wire. The multi-cap had leaked corrosive goo. All electrolytics were replaced, along with every non-disc coupling cap, safety cap, etc.
Several out-of-spec resistors were replaced as well. I added an adjustable bias control and 10 ohm safety resistors on the cathodes of the 7591s.
I undid some "mods" that a previous owner made, and then modified the headphone circuit slightly. I relubed all of the controls; replaced lamps, etc.
I had a pair of Sansui OPTs from a 1000A - they bolted in place with minimal fuss. They were slightly bigger than the original Kenwoods; they didn't have a 4 ohm tap (which was used for the headphone circuit exclusively). Otherwise, they were a great fit.
I bought some EH 7591s from Jim McShane. Plate voltage on these is 506 VDC! I've got them biased at 22.5 mA which is under the 70% recommended bias setting.
I fired it up and it works. FM MPX needs some adjustment (no surprise) and there is a bit of hum in the AM section to track down, but the AUX sounds glorious.
I think the Sansui iron is an upgrade for this model. If any of the other 1100u's that I worked on sounded this good, I wouldn't have sold them!