I just picked up a Crosley 51 at a swap meet the other day and am now building a power supply for it. The info I got off the internet talks about using a c bias or not. Saying it was optional to use a C battery and if you do you will get a little more volume.The radio even has a wire sodered in that you must remove to connect a C battery. What are your thoughts on this? is it worth it?
Thanks
Tom

Tom, here is the schematic: http://www.nostalgiaair.org/PagesByModel/372/M0003372.pdf

For a C- supply, I'm using a 3.7-V lithium battery with pigtails. I have it wired inside the cabinet. Such batteries are often available from the discount/surplus electronics places for a couple of bucks. Since no current is drawn, it should last the shelf-life.

You can try it with and without a C- supply, but as simple as it is, I would go with one. The ideal bias depends upon the audio tube you use and the plate voltage. My 3.7V is actually about half the bias recommended for an '01A at 90V.

Either way, this 2-tube regen set puts out little power. It's most practical with earphones, but strong stations can drive a high-impedance loudspeaker. Actually, I would avoid earphones since you could have B+ across your noggin.

To increase the volume, you can jack up the B+ voltage on the audio tube - above the 45V shown on the schematic. Like I said, I'm running 90V.

Best to make sure that the audio tube has good cathode emission. If weak, you can rejuvenate an '01A.

I also have a Crosley 52. It is similar to a 51, except it has three tubes - thus more power.
Doug

:I just picked up a Crosley 51 at a swap meet the other day and am now building a power supply for it. The info I got off the internet talks about using a c bias or not. Saying it was optional to use a C battery and if you do you will get a little more volume.The radio even has a wire sodered in that you must remove to connect a C battery. What are your thoughts on this? is it worth it?
:Thanks
:Tom

Doug, Thanks for the help, I got the schematic from this site. I also found a copy of the "Instructions for Operating The Crosley 51 Radio Receiver" on the internet, and it recomends using 90 volts when '01A's are used. In fact the booklet says to use 4 1/2 to 7 1/2 volts with the higher value to be used whe 90 volts is used on the output plate. When reading the instructions, it just says "manufactures of vacuum tubes state that the efficiency of a tube as an amplifer may be increased by the use of a C or grid battery, particulary when plate or B battery voltage of 67 or 90 volts are used." Also other sites I have found make it sound like a C battery is not needed. So I was just wondering what others that have a 51 think.
Your right about the two tube radios being able to drive a horn speaker, My Radiola III does real well driving a horn, and that is what I will do with the Crosley, if nothing else, just to drive the Wife and kids crazy!
Thanks again
Tom

:Tom, here is the schematic:
http://www.nostalgiaair.org/PagesByModel/372/M0003372.pdf
:
:For a C- supply, I'm using a 3.7-V lithium battery with pigtails. I have it wired inside the cabinet. Such batteries are often available from the discount/surplus electronics places for a couple of bucks. Since no current is drawn, it should last the shelf-life.
:
:You can try it with and without a C- supply, but as simple as it is, I would go with one. The ideal bias depends upon the audio tube you use and the plate voltage. My 3.7V is actually about half the bias recommended for an '01A at 90V.
:
:Either way, this 2-tube regen set puts out little power. It's most practical with earphones, but strong stations can drive a high-impedance loudspeaker. Actually, I would avoid earphones since you could have B+ across your noggin.
:
:To increase the volume, you can jack up the B+ voltage on the audio tube - above the 45V shown on the schematic. Like I said, I'm running 90V.
:
:Best to make sure that the audio tube has good cathode emission. If weak, you can rejuvenate an '01A.
:
:I also have a Crosley 52. It is similar to a 51, except it has three tubes - thus more power.
:Doug
:
:
::I just picked up a Crosley 51 at a swap meet the other day and am now building a power supply for it. The info I got off the internet talks about using a c bias or not. Saying it was optional to use a C battery and if you do you will get a little more volume.The radio even has a wire sodered in that you must remove to connect a C battery. What are your thoughts on this? is it worth it?
::Thanks
::Tom