I have a 1935 623F Philco. I built a battery eliminator for it. I want to make sure I under stand the -B and the +C together on on the schematic. I have my regulated 2.0 vdc,my 135vdc,my 67.5vdc,my plus and minus c voltage at 3 volt and 7.5 vdc.
Hi and welcome,
I built one years ago for a 37-33. It used newer tubes but the power requirements where the same. It's good to regulate the filament voltage so you don't have any mishaps. Used a lm 317 adj regulator and a 6.3v winding to power it. The hv isn't too critical. All your voltage sound good and even better if they are stable under load. The 19 is a pretty stout tube and can haul down a fair amount of plate current for a battery style tube.
GL
Hi Tigercat,
Yes,the B- and C+ are connected. The C and B voltages are referenced to common B-. The C battery is used for the grid biasing of the tubes. Grid bias is almost always a negative voltage. If you follow the negative from the C battery you'll find it's connected to control grids of the tubes.
Rod
So both C+(3 volt and 7.5 volt) are connected to B-.
Thanks to you both for the info.
Yes that is correct. So from B- your C voltages are -3v and -7vdc. B- isn't the lowest voltage -7 is. I know it's a little confusing.
Sorry about multiple post. Didn't think they were going thru. New to this game. Thanks again guys.
I have an earth ground hooked up to my chassis .It appears I have .65 amp draw on my 2 volt filament circuit at 1.7 volts but my tubes are not getting warm at all. I have my 3 volt + and -,my 7.5 + and -,my 67.5 is at 64 volt and my 135 volt is at 126.5. I was wondering if those readings are good enough
Looks ok. Battery tubes don't get hot like ac tubes as they don't dissapate anywhere close to the same amount of energy.
my battery eliminator voltages are all correct but when i turn my radio on the tubes will glow and i have static on the speaker for maybe 5 seconds and then the tubes get dimmer and dimmer till they go dark and the static stops and i still have 1.7 to 1.8 volts on all of my filaments .
on tube 19 i have 1.7 volts on my F pin;(-3.2 on both G pins;)120 volts on P pin.(all dc of course). On tube 30 driver i have 1.7 on F pin;(1.5 on G pin) and 125 on P pin;
on my I-C-6 Tube i have( 0 volts on pin G2 pin) ;126 on G1 pin; 126 on P pin;1.7 on F pin; and 64 on G 3+5 pin; on 34 IF tube i have 1.88 on f pin; 126 on P pin;
.24 on center; 62 on Sg; on tube 30 2nd,DET tube i have 1.82 on F pin;( -1.5 on P pin;) .012 on G PIN; On my 32 1st A.F. Tube i have 1.8 on F pin; 31 on Sg pin;
(103 on P pin;).
I( ) on the ones that are not what i have on my prints. Any thoughts?
Sorry for the late response but i have been out of town. i measured all my voltages from under side of the chassis. After all filaments go dark I still have the 1.7 to 1.8 volts on my filaments and on my dial pilot light. So to me that would clear the thought of a shorted capacitor. I figured i should have around .6 amps on the filaments circuit which I had but I will double check. I was also thinking a bad contact on the on/off switch. Thanks for your response.
You might want to remove a few of the tubes and measure the resistance across the to fat pins on the tube's base. Should register a low resistance (10 or 20 ohms or so).
Thanks
I will check them again and log resistance for each tube and try to shine all pins and "sockets" up.