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Title: HQ-120 Mystery Capacitor Post by: KW4H on July 14, 2023, 09:56:00 AM I’m in the midst of restoring a HQ-120X. This particular unit has been badly golden screwdrivered, so much of the work is reconstruction and validation against the schematic. I’m up to the second IF and have hit a bizarre snag. The mystery is C-85 (look on the attached schematic below the tube). It's connected from the junction of R-84 and R-86 to chassis. I can't find this capacitor in any photos I have of working HQ-120's, including the photos from the K3MSB website. I also brought up Carlson's video on YouTube and zoomed in on the area, and still can't find it! Anyone here run across this before and know where C-85 is supposed to be located? As far as I can tell, it would exist in only one place -- directly off of the junction of R-84 and R-86 to chassis. Another possibility is that C-85 is on the diagram but was never installed in the radio in production for some reason.
73 - Steve, KW4H Title: Re: HQ-120 Mystery Capacitor Post by: KW4H on July 14, 2023, 10:50:40 AM C-85 was just found. After some more squiggling and zooming in on spots in Carlson's video -- there it is (see the arrow). It's tucked below the patchwork of resistors and capacitors on the side panel. The banded end is connected to the chassis, and if you zoom in some you can just barely see the other end connected to the junction of R-84 and R-86. This capacitor does not appear to be in the photos on the K3MSB website, either before or after restoration. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
73 - Steve, KW4H |