Rap 'n Tap
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From: Bill Dufendach
Date: 5/3/2005
Time: 7:57:22 PM
Remote Name: 65.137.91.57
I cannot tell you, John, what is wrong with your RA/DA, but I have one that tunes the band properly. It works with a signal generator, but without a long antenna, which I didn't have, I could not pick up any stations clearly. I was powering it with a power supply rather than batteries, and the hum level was too high even though the supply was well regulated. It is a beautiful piece of work, isn't it. I am planning to sell mine on Ebay.
From: Bruce B.
Date: 4/8/99
Time: 11:11:17 PM
Remote Name: 24.131.150.94
Sorry for slow response. Yes, the AM comes in when the guitar is not plugged in, but the device must be on. If I touch the tip of the phone plug (from the input of the device) that would normally go into the guitar, the AM comes in loud and clear. The cable used is shielded, phone plugs on the ends. The case is aluminum. If plugged into a battery-powered amp, the AM is very low in volume, unless I approach a piece of equipment that is plugged into the wall! If I approach this equipment and unplug it from the wall, the AM will decrease significantly. The device is commercially made and I am in touch with the designer. His equipment is basically custom-made and he has experienced problems in areas with very strong AM stations, like Chicago. Yes, when I touch the case of the device or the A/C powered amp (not going thru the battery-powered amp) the AM changes in volume. I changed the house ground system to a #4 copper stranded cable out to an 8 ft copper ground rod sunk 7ft 7in in the ground. About 2.5 ft of copper stranded cable from the fuse box to the ground rod. I added .01 capacitors to ground from each leg of the A/C multi-outlet box I plug amps into.
Whew! I think I got most of your questions. I have tried 47pf caps to ground on the input and output. I have tried to add a filter on both the input and output (four 80 uH coils in series with five 7pf caps to ground at the beginning and end and in between each two coils. (standard ham filter config out of the Handbook). The device uses 5 bipolar transistors, two Ge diodes, lots of 10uF caps. It is a very high gain device. The filters I tried were too detrimental to the sound. Maybe I should try the filter on just the output. The AM is not 'effected'. It sounds just like a radio and must be getting detected before the high gain front end, although the input volume control increases the AM volume. Thanks, Bruce