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Author Topic: HW100 - osc changing mode switch  (Read 2146 times)
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kd1nw
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« on: November 19, 2017, 12:26:41 PM »

Hi Folks,

Sorry, I know its not an AM rig, I hope thats okay. When changing the mode switch between cw, usb, lsb there is a loud screeching oscillation. Trying to track it down but wanted to check to see if anyone has had this happen.

Thanks
Kevin
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WD4DMZ
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« Reply #1 on: November 19, 2017, 07:16:17 PM »

I had issues with this switch on an HW100 and 101. Both had cracks in the wafer farthest from the front causing bad or intermitent contact. Found a switch someone was selling on a yahoo heathkit forum and used it in the 100. Works just fine now.

The HW100 wafer was clearly broken but the 101 was just enough of a hairline to allow the wafer to bow and bend. Look hard for cracks at 3 and 9 o'clock by the bolts holding the switch wafers together.

Rich
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kd1nw
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« Reply #2 on: November 20, 2017, 08:36:00 AM »

Hi Rich,

Thanks for the tip. I checked it out carefully and it looks okay

When I remove V16 12AU7 the osc is continuous. Looks like I need to check things in this area

73 Kevin
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kd1nw
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« Reply #3 on: November 23, 2017, 09:43:09 AM »

Hi All,

I found that touching either pin 8 or 9 on V13C stopped the problem. Strangely enough after a couple of times of doing that by touching R123 470 ohm the radio seems to be stable. I turned it off and on a few times letting cool down and so far so good. The receiver is working very good right now. I'll bet the problem reappears again but at least i know where to look. Maybe a flaky solder joint.

Thanks 73
Kevin
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