[hpsdr] Thermalcouples and digital attenuators

[FRANCIS CARCIA]

I came into a spool of thermalcouple wire the same time I was building my passive solar room. I had the bright idea of putting thermal couples in the rock bed to measure the stored heat. I didn't want a mechanical bond so I came up with an idea to weld the ends. I charge up a big cap 30,000 ufd, if I remember, to 30 volts then make a carbon rod from a drafting pencil lead ( remember before cad schematics) A couple clip leads one to the carbon rod and the other to behind the joint to be welded. I twist the ends and strike an arc. There is enough energy in the cap to do a nice weld. 
  I suppose a current limited power supply would work but you still need toe carbon rod to control the slag blob from exploding.
   
  Be careful with digital step attenuators. Sometimes the control signals can cross talk to the rf channel causing clicks as it steps up and down. I spend many hours trying to make the worlds best noise blanker that just replaced the noise with a click. 
  I think this isolation number is included in the data sheet.     frank
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