Re: SX-28A Hum
开云体育Tom Good for you Presumably, the base “In” position filters out the hum as expected… And the hum comes from upstream, maybe the AF gain? Pot area or a bad contact in the phones switch, or even before that. ?? ? From: [email protected] [mailto:[email protected]] On Behalf Of thoyer via groups.io
Sent: Thursday, February 13, 2025 7:22 PM To: [email protected] Subject: [HallicraftersRadios] SX-28A Hum ? I just finished pretty much a complete overhaul of a nice condition (physically) SX-28A. Replaced just about every resistor and all caps. ? Radio is working well except for a 120hz hum. When I switch the Bass in, the hum goes away. ? Yes, there is ripple on the plates of the 6V6’s, about 6vrms, but that is there independent of the bass switch position. The output side of the HV filter is clean, no ripple. I paralleled another 47uf 450v cap across the choke input cap and there was no difference. ? I double checked the wiring against the schematic along with component values. Is the schematic correct in this area? I found once schematic error maybe there is another? ? Thoughts? ? Tom W3TA -- don??? va3drl |
don Root