[Central-Electronics] 600L coupler replacement

[Kihwal Lee]

 blockquote, div.yahoo_quoted { margin-left: 0 !important; border-left:1px #715FFA solid !important; padding-left:1ex !important; background-color:white !important; }   My 600L had a  bad ouput coupler on 10m and 15m. Each one has been replaced with a pi matching network. In the process of designing the networks, the working ones were analyzed. They are designed to match 3900 ohms to 50 ohms and that's exactly what Joe Batchelor's coupler patent uses as an example. 
Details at http://k9sul.fayoly.net/projects/ce600l/ 
One thing that still doesn't work is the load mismatch relay, which I replaced with a modern 110VDC 10kohm coil relay. It gets engaged at first when the plate supply is turned on. But if the plate supply is turned off and turned back on, the relay doesn't engage. Pushing the reset button or sensitivity adjustment doesn't help. 
This is a beaten up unit with extra holes here and there, so I do not care too much about preserving the original circuit and the look. 
73,Kihwal, K9SUL

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