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THE AM BULLETIN BOARD => Technical Forum => Topic started by: kd1nw on November 19, 2017, 12:26:41 PM



Title: HW100 - osc changing mode switch
Post by: kd1nw 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


Title: Re: HW100 - osc changing mode switch
Post by: WD4DMZ 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


Title: Re: HW100 - osc changing mode switch
Post by: kd1nw 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


Title: Re: HW100 - osc changing mode switch
Post by: kd1nw 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
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands