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  #1  
Old 06-03-2023, 10:30 AM
fumplet fumplet is offline
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still working on correct capacitor for line and tube voltages. Right now 7.3uf gets me 6.2 volts on tube filaments. Should I be worried about .1 of a volt Im not sure. Cannot use the fancy formula in another thread as it is supposed to use microsoft excel which requires me to go purchase microsoft 365. Swapping and combining caps is more fun anyway.
Just looked at meter and its now showing 6.24 volts. It seems to vary just like the line voltage so Im betting thats close enough.
Next is to hunt for the 300 ohm volume resistor unless its in the volume pot itself.
I have yet to figure out why bumping the tuner gets radio to play like tuner fins are losing connection to the fixed part of the tuner. Experience is telling me connection or coil bad somewhere.
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  #2  
Old 06-04-2023, 08:46 AM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by fumplet View Post
still working on correct capacitor for line and tube voltages. Right now 7.3uf gets me 6.2 volts on tube filaments. Should I be worried about .1 of a volt Im not sure. Cannot use the fancy formula in another thread as it is supposed to use microsoft excel which requires me to go purchase microsoft 365. Swapping and combining caps is more fun anyway.
Just looked at meter and its now showing 6.24 volts. It seems to vary just like the line voltage so Im betting thats close enough.
Next is to hunt for the 300 ohm volume resistor unless its in the volume pot itself.
I have yet to figure out why bumping the tuner gets radio to play like tuner fins are losing connection to the fixed part of the tuner. Experience is telling me connection or coil bad somewhere.
With the V/C fully CW, check the cathode voltage on RF amp, pin 5, should be 2-3 volts. That will prove that the 300 resistor is part of the volume control. If not, wire in a 330 ohm resistor in series with the high end of the V/C and the cathode. Has the .1 MFD capacitor from the cathode been replaced.
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  #3  
Old 06-05-2023, 08:39 AM
Alex KL-1 Alex KL-1 is offline
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Join Date: Jan 2021
Location: Brazil (Paranį)
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Quote:
Originally Posted by fumplet View Post
still working on correct capacitor for line and tube voltages. Right now 7.3uf gets me 6.2 volts on tube filaments. Should I be worried about .1 of a volt Im not sure. Cannot use the fancy formula in another thread as it is supposed to use microsoft excel which requires me to go purchase microsoft 365. Swapping and combining caps is more fun anyway.
Just looked at meter and its now showing 6.24 volts. It seems to vary just like the line voltage so Im betting thats close enough.
Next is to hunt for the 300 ohm volume resistor unless its in the volume pot itself.
I have yet to figure out why bumping the tuner gets radio to play like tuner fins are losing connection to the fixed part of the tuner. Experience is telling me connection or coil bad somewhere.
No worries with 6.2V on 6.3V filaments. I use 5.9V for 10 years in one circuit I've made for audio, with ECC88, using almost every day, and tubes measures almost like new.
Even for power tubes, a little deviance is allowed, and will work perfectly.
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Last edited by Alex KL-1; 06-05-2023 at 08:43 AM. Reason: More info.
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