RCI 2980 EPT360014B 3 problems
- Thread starter ira parker
- Start date Friday at 5:54 PM
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ira parker
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The short story, No tx got that resolved. Once tx was restored there is a 4-6 watt dead key on sideband ? Also only about 10 watts output on ssb and vr#12 doesn't adjust it? AM works fine rx and tx, 22 watts out audio chain is good. Pll/vco took alignment just fine spot on frequency. Started Tx alignment bias is still a little low not sure about these hg transistor (2166,2312s) from ica manufacturing. When I got too setting high/low dead key vr#13 adjusted normal high side 8 watts however vr#16 low side would not respond, first checked the vr itself has range on the ohm meter but 0 volts. Modulation has been opened so vr#14 is mute. Vr #12 does adjust from 6.14 volts down to 0.21 volts on am, 1.77 volts to 0.03 volts on ssb both test with rf power fully clockwise, tr51 and tr50 have been replaced and voltage is correct and switches to 13 volts ssb. Voltage is present and switching with pcb board in place at tp7,8 and 9. I've started testing and checking the other transistors tr12 (good voltage good), tr17 gvg, tr 23 gvg, tr 30 gvg, tr 31 gvg, tr 34 gvg, tr 47 was bad replaced it gvg, tr 53 gvg. That's as far as I got yesterday and today working over the weekend hopefully back at it monday. Just looking for any advice or something obvious or if anyone has run across this before. Going to finish the transistors first then start tracing back from vr #16 2 legs to the back of radio 1 to the front. Back right is ground back left and front are in circuit so I'll see where it leads me.
Thanks Ira,
P.S. using the dx11b for board layout and schematics and the dx99v for transistor and ic voltage charts.
Update I've cleaned up the dead key on ssb driver bias was to low.
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