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I did my best there without changing parts in the oscillator circuit. I was able to set the LSB carrier to the 7.7975 the filter was designed for (instead of the 7.7985 called for in the cobra manual), but I could only get to 7.8023 on USB, not 7.8025. From the last sweep I did, it looks like the carrier would be around the -20dB part of the filter response on USB. -20dB on top of the work the balanced modulator is doing should get it down there quite low.

The radio board has been removed from the mobile chassis so I cannot test this until I get it installed into the base chassis (pots hanging free, no coax connector etc). I did recall seeing a carrier when looking for spikes in the other sideband yesterday, but with the mic gain all the way down in SSB, it was down at the same height as the noise that made it through the filter.

I will check this again once I get it together, but it will take some doing because the boards were not the same size. It might take a couple days to figure out the best way of making it fit. If I have to change trim caps to get that extra 200Hz higher on the USB carrier, I can cross that bridge when I get there.

Thank you for pointing that out! I will get some screenshots of the output posted here when I get that far. Learning is the only reason I help my friend fix these broken radios he keeps buying. That's literally all I get out of it, and I'm more than happy with that until I earn my golden screwdriver certificate and have the confidence to charge something.

<blockquote data-quote="brandon7861" data-source="post: 828048" data-attributes="member: 53724">I did my best there without changing parts in the oscillator circuit.&nbsp; I was able to set the LSB carrier to the 7.7975 the filter was designed for (instead of the 7.7985 called for in the cobra manual), but I could only get to 7.8023 on USB, not 7.8025.&nbsp; From the last sweep I did, it looks like the carrier would be around the -20dB part of the filter response on USB.&nbsp; -20dB on top of the work the balanced modulator is doing should get it down there quite low.The radio board has been removed from the mobile chassis so I cannot test this until I get it installed into the base chassis (pots hanging free, no coax connector etc).&nbsp; I did recall seeing a carrier when looking for spikes in the other sideband yesterday, but with the mic gain all the way down in SSB, it was down at the same height as the noise that made it through the filter.I will check this again once I get it together, but it will take some doing because the boards were not the same size.&nbsp; It might take a couple days to figure out the best way of making it fit.&nbsp; If I have to change trim caps to get that extra 200Hz higher on the USB carrier, I can cross that bridge when I get there. Thank you for pointing that out!&nbsp; I will get some screenshots of the output posted here when I get that far.&nbsp; Learning is the only reason I help my friend fix these broken radios he keeps buying.&nbsp; That&#039;s literally all I get out of it, and I&#039;m more than happy with that until I earn my golden screwdriver certificate and have the confidence to charge something.</blockquote>

[QUOTE="brandon7861, post: 828048, member: 53724"] I did my best there without changing parts in the oscillator circuit. I was able to set the LSB carrier to the 7.7975 the filter was designed for (instead of the 7.7985 called for in the cobra manual), but I could only get to 7.8023 on USB, not 7.8025. From the last sweep I did, it looks like the carrier would be around the -20dB part of the filter response on USB. -20dB on top of the work the balanced modulator is doing should get it down there quite low. The radio board has been removed from the mobile chassis so I cannot test this until I get it installed into the base chassis (pots hanging free, no coax connector etc). I did recall seeing a carrier when looking for spikes in the other sideband yesterday, but with the mic gain all the way down in SSB, it was down at the same height as the noise that made it through the filter. I will check this again once I get it together, but it will take some doing because the boards were not the same size. It might take a couple days to figure out the best way of making it fit. If I have to change trim caps to get that extra 200Hz higher on the USB carrier, I can cross that bridge when I get there. Thank you for pointing that out! I will get some screenshots of the output posted here when I get that far. Learning is the only reason I help my friend fix these broken radios he keeps buying. That's literally all I get out of it, and I'm more than happy with that until I earn my golden screwdriver certificate and have the confidence to charge something. [/QUOTE]

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