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RCI 6900F w/EPT990013B

Cable Guy

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Dec 29, 2010
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Hi, I can't find any info on this revision of board, the closest I can find is the 990010X on cbtricks. Does anyone know of any source for schematic?
Thanks
 

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Anyways, this radio has an issue I haven't solved yet. After alignment, which is spot on, AM seems great, but SSB on the LO bands is watery on TX and RX. SSB on the HI bands are clearer, but slightly distorted. I followed the LO/HI switch to the separate xtal oscillators/varactors, and each xtal oscillator has it's own set of 3 inductors, for AM/LSB/USB. I looked at the varactor for the LO osc, its okay. Then I looked at the xtal, it's okay also. Voltages steady. So I though maybe balance modulator, but it does it mostly on LO, with only slight distortion on HI, and I figured it would do it equally on LO and HI if the BalMod was screwy, but I could be wrong.

I'm also thinking FL3, the xtal filter could be at fault, seeing as how it does appear to be a frequency issue as far as I can tell, like I said, slight distortion on the HI bands, and gets worse the lower you go. IDK yet.
 
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I don't think the filter is at fault, as ch1 on HI passes ssb okay, but ch40 on LO with the 10k switch engaged is the same frequency and it's watery and distorted. I feel it has to be in the LO xtal oscillator. Putting it aside for the moment.
 
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Thanks for looking. All checks were performed with the shorting bar removed and sniffing with the sdr, so no ssb linear issues from incorrect PA bias. I found 2 electrolytic capacitors faulty, replaced but no fix. This radio is probably needing a recap.
 
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