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 Post subject: Sonora rdu209
PostPosted: Jan Thu 12, 2017 5:11 am 
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Joined: Dec Sun 13, 2015 2:17 am
Posts: 116
Could someone explain to me where this radio gets its plate voltages from? Ive read the schematic a thousand times, but it just doesnt click with me.meIm also not understanding the 35z5 rectifier. I know that it makes pulsating dc that gets filtered, but where does the dc leave this tube and go to the radio?


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 Post subject: Re: Sonora rdu209
PostPosted: Jan Thu 12, 2017 5:21 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11344
Location: San Jose, CA USA
AC goes into the 35Z5 rectifier on the plate (after going through the dial lamp and part of the 35Z5 filament). The DC starts at the cathode of the 35Z5, which is pin 8. From there it goes through a 33 ohm resistor to the first filter cap (40 uF). From that point, there is a B+ feed to the output transformer. Note that this is a tapped output transformer. The bottom part of the primary coil is a "hum canceling" winding, and the B+ feed to the rest of the radio goes out the bottom terminal of the output transformer through a 1200 ohm resistor to the second filter cap (also 40 uF). From this point, all the rest of the radio gets its B+.

Schematic available here: http://www.radiomuseum.org/r/sonora_rad_rdu209.html

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Tom K6VL


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 Post subject: Re: Sonora rdu209
PostPosted: Jan Thu 12, 2017 7:02 am 
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Joined: Feb Sat 06, 2016 1:47 am
Posts: 1999
Location: Santee Calif. 92071
Good explanation above. The 35Z5 is a diode. Makes AC into 1/2 wave DC. Gets filtered by capacitors to remove AC ripple. Has voltage divider resistor for screen voltage.


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 Post subject: Re: Sonora rdu209
PostPosted: Jan Fri 13, 2017 10:50 pm 
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Joined: Dec Sun 13, 2015 2:17 am
Posts: 116
Thanks for the help. Moderator Please close this. Thanks


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Post New Topic Post Reply  [ 4 posts ]  Moderators: Marcc, Norm Leal

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