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 Post subject: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 1:13 am 
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Joined: Sep Mon 18, 2017 2:23 am
Posts: 107
Location: Plymouth, MI
I purchased a "working" Radiola RS. Hooked it up tonight and can't get anything out of it. Using a battery eliminator that had the filament voltage running high so I added a 24k resistor to bring it down to 1.1 volts. B voltage is 44v and if I have it hooked up right, no C or bias voltage on this radio. Antenna, ground connected and using a good pair of "Little Tattler" headphones which work fine on my Radiola III. Tubes are WD-11's and both filaments check good. I can pick up a slight buzz in the headphones when I touch the connection terminals for them. Any guesses as to what I am doing wrong?


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 1:33 am 
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Location: Livermore, CA
A 24K resistor is too high of value to be in series with filaments. WD11 draw .25 amps so 4 ohms will drop 1 volt (1 tube). Not sure what you are using for "A" supply?

http://www.nostalgiaair.org/pagesbymode ... 040353.pdf

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 1:39 am 
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Joined: Sep Mon 18, 2017 2:23 am
Posts: 107
Location: Plymouth, MI
The battery eliminator was running high at 2.4v. It's not adjustable on this eliminator. Adding a 24k resistor brought it down to 1.1v for the WD-11 tubes. The resistor is hooked up between the A- terminal on the eliminator and the negative wire to the radio.


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 1:42 am 
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Location: Livermore, CA
If 24K brought it down to 1.1 volts tubes aren't drawing filament current. Do you see filaments glowing?

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 1:47 am 
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Joined: Sep Mon 18, 2017 2:23 am
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Location: Plymouth, MI
No glowing. If I hooked it up with the 2.4 volts, wouldn't that blow the filaments right away? Would keeping the filament voltage knob at the low end protect the tubes?


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 2:05 am 
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Joined: Sep Mon 18, 2017 2:23 am
Posts: 107
Location: Plymouth, MI
You were right Norm. I removed the resistor and the radio worked, although I shut if off after about 20 seconds or so because I was afraid the 2.4v would blow the tubes, even with the filament voltage kept at the low end. Not really sure about that but wanted to be safe.


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 3:09 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11539
Location: S. Dartmouth MA 02748-1225 USA
Congrats!


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 4:00 am 
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Joined: Sep Mon 18, 2017 2:23 am
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Location: Plymouth, MI
Now I'm wondering if I can use an external potentiometer to drop the 2.4v to 1.1v and still allow the tubes to draw the amps they need?


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 4:44 am 
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Location: Oxford, MI
Is the 2.4V from the power supply being measured with the radio connected and turned on or not? If measured without the power supply being loaded by the tube filaments it could rise to this point assuming the supply is not regulated but relies on the tube current to set the voltage.

Try measuring with the radio on and compare.

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 4:48 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Livermore, CA
Rheostat on your radio should reduce filament voltage. If still too high add 2 ohms in series. Since you have two WD11's voltage will be dropped by 1 volt.

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 9:16 pm 
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Joined: Sep Mon 18, 2017 2:23 am
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Location: Plymouth, MI
Power supply is regulated and runs 2.3v when radio is on. Hey Norm, I'm new at this so explain to me how 2 ohms in series will drop the voltage to 1.1v when it took me 24k to drop it that far. What am I missing? Yes I am a little dense at times! :lol:


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sat 02, 2017 9:36 pm 
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You have two WD11 tubes in parallel. Each tube draws .25 amps. So two will draw .5 amps. Using ohms law it takes 2 ohms to drop 1 volt.

1 volt / .5 amps = 2 ohms.

Voltage divided by current equals resistance.

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sun 03, 2017 3:01 am 
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Location: Oxford, MI
atwaterkent1 wrote:
Power supply is regulated and runs 2.3v when radio is on. Hey Norm, I'm new at this so explain to me how 2 ohms in series will drop the voltage to 1.1v when it took me 24k to drop it that far. What am I missing? Yes I am a little dense at times! :lol:


Well, it's clearly not regulated or the regulator is set incorrectly if it's supposed to be supplying 1.5V and the actual output is 2.3-2.4V.
Do you have a schematic for this power supply or is it a homebrewed affair?

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Sun 03, 2017 3:17 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7751
Location: Cleona, PA
Maybe it's just me, but I would not be experimenting with or even using WD-11 tubes. They are going for $100 and up for used and for several times that for NOS. One wrong move and <poof>. There are many possible subs to use while setting things up, requiring socket adapters. It's all been worked out if you look around.

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Mon 04, 2017 3:09 am 
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Joined: Sep Mon 18, 2017 2:23 am
Posts: 107
Location: Plymouth, MI
Your right newt, but I had some good luck and the right circumstances and found some for far less than the going rate. Still want to be careful with them though.


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Mon 04, 2017 3:10 am 
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Joined: Sep Mon 18, 2017 2:23 am
Posts: 107
Location: Plymouth, MI
Sorry Reece, missed your name first quick read through.

Dan


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Tue 05, 2017 12:52 am 
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Joined: Sep Mon 18, 2017 2:23 am
Posts: 107
Location: Plymouth, MI
Just received the second power supply I ordered from the same guy. Checks out good at 1.543v. Sending first power supply back for refund. So the design is good I just got one with a bad component. Can you safely run WD-11's at the 1.5 volts or is that still too high.
By the way, if you really look around, you can find WD-11's for a lot less than $90.00.


Dan


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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Tue 05, 2017 1:05 am 
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Joined: Sep Sat 27, 2014 4:24 am
Posts: 1374
Location: Oxford, MI
WD-11s can't be run at 1.5V since the filament is rated at 1.1V. The Radiola RS using Wd-11s can be run at 1.5V since this is the voltage of a standard carbon zinc cell for which it was designed and it has a filament rheostat which adjusts the voltage to the tube.

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 Post subject: Re: Radiola RS Help!
PostPosted: Dec Tue 05, 2017 1:47 am 
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Joined: Sep Mon 18, 2017 2:23 am
Posts: 107
Location: Plymouth, MI
Thanks guys!


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