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The 6K8 is the converter oscillator. When I put my finger on the top
to the tube, which has a cap that runs to the tuning mechanism, the received signal becomes louder. It seems to happen on all bands. The lower ends of each band are affected the most. I do have about a ten foot wire connected to the antenna terminal. I also have another S-20R which functions normally with respect to the received signal. I hope this is the info you're asking for. Your help very much appreciated. Straydog wrote: On Tue, 25 Apr 2006, Rod wrote: Hello, I'm restoring a Hallicrafters S-20R. I've managed to bring it back from the grave by installing new caps, a few new resistors and replacing a bad tube. Although its back to life, it still has some issues, one I hope someone here can help with. When I touch the cap of the 6K8 tube with my finger, the audio becomes much louder. Or the sensitivity increases. I don't recognize what the 6K8 is. Audio first stage (diode-triode)? or Mixer? A fair number of some of these tubes have, as the cap, the connection to the control grid. If its an audio tube, then you should be introducing more 60 cycle hum than anything else. When you say "the audio becomes much louder" are you talking about the audio on the signal you are listening to or background static or hum or what. I'm not at all familiar with Hallicrafters before about S-38, S-40 vintage. Give us all some more clues, and tube listing. I've read all the other responses up to the moment of writing this posting; most are worth checking out. If the cap is the control grid of the mixer, then just maybe you are injecting--by capacitance pickup with your body (as antenna)--more broadcast RF into the circuit than is coming in normally through whatever else the input RF goes into (RF amplifier, coils, caps, whatever). In my experience, lots of times you can touch the antenna terminal of a receiver and pick up a lot of signal that would not be there if that terminal were not connected to anything. Not sure which. But my question is why? What should I look for in order to have the radio play at the volume without holding my finger there. It gets very boring. Any help would be appreciated. |
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