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just came across this Macroni model 80 radio, my winter project.Removing radio from cabinet and dusted the old girl I noticed something missing ,In the schematic the two components that I believe are crystals , 1 located under R4 other under R6 . ,And one is missing.Can these be replaced with a diode and if so what type.Will try to upload schematic..
What you see under R4 and R6 are not crystals, they are bias cells. You can replace them with a small 1.5 battery, the kind you use in hearing aids.
They just supply a negative voltage to the grid of the tub
. Dan in Calgary
Thank you very much .I assumed they were crystals as part list shows a listing for crystal.
Learned something new.
I finally found some photos of the replacement of bias cells.. This is the system I use.
The battery holders are a little big for the 1.5 volt batteries , so I hot glue the smaller batteries in place
You can use any method you want , but make sure the polarity is correct.
Dan in Calgary.
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