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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 1:23 am 
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jrehkopf wrote:
Whoa, Don! What happened to .16 amps, no matter what? Unresolved questions cause confusion.


I plugged the meter lead into the 10 amp receptacle on the meter as Tom suggested and got the new and correct numbers thus the numbers that I posted above are correct. Unfortunately I still don't have near enough current so I went back to the drawing board in a post prior to that. Several individuals have suggested using a battery like the picture of the one that I posted with a resistor but I need to know what size of resistor. It seems to me that it would have to be a heavy duty wire wound resistor to me but I have been wrong many times before. :)

Thanks for your reply and looking forward to many more.

Don


Last edited by IGot2P on May Mon 18, 2020 2:28 am, edited 1 time in total.

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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 1:27 am 
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One word of caution Don. As it says on the front of that battery... No sparks or open flame!
The hydrogen gas from a lead acid battery (sealed or not) is no joke. Had a car battery explode under the hood once. Glad I wasn't there and the hood was closed.
73,
-marc


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 1:49 am 
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Quote:
but I need to know what size of resistor. It seems to me that it would have to be a heavy duty wire would resistor to me but I have been wrong many times before.

Ohm's law and the power formula.

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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 4:33 pm 
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Don,
As Jim says, Ohms law.
You need 6 amps at 3vdc for the filaments. So the dropping resistor needs to drop 3v at 6a also.
R=E/I R=.5 P=IE P=18 watts. Resistor power, here on ARF is usually doubled. So, .5ohm @ 35watts.
73,
-marc


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 4:41 pm 
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Location: Santa Rosa, CA
Using a dropping resistor works well in cool climates! 18 Watts is a lot of power to waste and also results in faster discharge of your batteries.

Rich


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 4:46 pm 
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Totally agree Rich. Big heater!
Go back to AC transformer.
73,
-m


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 5:04 pm 
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IGot2P wrote:

I plugged the meter lead into the 10 amp receptacle on the meter as Tom suggested and got the new and correct numbers thus the numbers that I posted above are correct.

Don

OK, got it. Question answered, thanks.

If I recall, the two second audio tubes are in parallel; you could run the radio with only 1 of those tubes, maybe using your variac, for a test.

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 5:50 pm 
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mbruvry wrote:
Don,
As Jim says, Ohms law.
You need 6 amps at 3vdc for the filaments. So the dropping resistor needs to drop 3v at 6a also.
R=E/I R=.5 P=IE P=18 watts. Resistor power, here on ARF is usually doubled. So, .5ohm @ 35watts.
73,
-marc


Marc, that is the same numbers that I got so thanks for verifying. Not sure I can find a power resistor like that...if so, I may need to turn the air conditioner on. :D

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 5:55 pm 
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Location: SE Iowa 52626
mbruvry wrote:
Totally agree Rich. Big heater!
Go back to AC transformer.
73,
-m


I agree but I am having a problem finding a transformer that meets my needs. If you can point me to one it would be appreciated.

In the meantime how about the 6 volt battery and this unit at https://www.ebay.com/itm/DC-DC-Converte ... 1438.l2649 ?

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 5:58 pm 
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jrehkopf wrote:
IGot2P wrote:

I plugged the meter lead into the 10 amp receptacle on the meter as Tom suggested and got the new and correct numbers thus the numbers that I posted above are correct.

Don

OK, got it. Question answered, thanks.

If I recall, the two second audio tubes are in parallel; you could run the radio with only 1 of those tubes, maybe using your variac, for a test.


Jeff, I had actually thought of this interesting idea but just have not got around to trying it yet. I would still be a bit short on current but it might give me a hint about the radio in general.

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 6:18 pm 
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IGot2P wrote:
In the meantime how about the 6 volt battery and this unit at https://www.ebay.com/itm/DC-DC-Converte ... 1438.l2649 ?

Don

I have one of these and it works fine to run my old 3v and 6v battery radios. https://www.amazon.com/gp/product/B078Q ... UTF8&psc=1

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 6:24 pm 
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jrehkopf wrote:
IGot2P wrote:
In the meantime how about the 6 volt battery and this unit at https://www.ebay.com/itm/DC-DC-Converte ... 1438.l2649 ?

Don

I have one of these and it works fine to run my old 3v and 6v battery radios. https://www.amazon.com/gp/product/B078Q ... UTF8&psc=1


It looks great for my use. What type of battery are you using for the input? I was looking at the one at https://www.ebay.com/itm/ExpertPower-6V ... 1438.l2649 . Do you think that it would work well for my use?

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 7:46 pm 
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I am using a 12 volt riding mower battery. Easy to recharge.

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 9:49 pm 
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Location: SE Iowa 52626
jrehkopf wrote:
IGot2P wrote:
In the meantime how about the 6 volt battery and this unit at https://www.ebay.com/itm/DC-DC-Converte ... 1438.l2649 ?

Don

I have one of these and it works fine to run my old 3v and 6v battery radios. https://www.amazon.com/gp/product/B078Q ... UTF8&psc=1


I just read ALL of the Q & A about that unit and several stated that the output was limited to only 4 amps. If this is correct, it would not work for me. Can you verify that I can get 6 amps at 3 volts output with a battery similar to yours?

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 10:51 pm 
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Specs says it does...and for $10 shipped. :wink:
You could try it using a car battery before buying a 6V battery.


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Last edited by Mike Toon on May Tue 19, 2020 2:46 am, edited 1 time in total.
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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Mon 18, 2020 11:16 pm 
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You have to read those q&a carefully. Some of them didn’t know to take the paper off the plexiglas cover. Mine is the 12 amp version, I figured it is good for half that. I liked the volt/amp readout. I mentioned it because I know it works up to 4 amps and does not make noise. Just my experience.

I think you should try the 5 tube/variac setup. At the end of the other thread there is a diagram of the wiring using 2 capacitors to provide the ground connection.

The one you showed on eBay should work but I can’t say if it might be noisy.

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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 12:29 am 
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[quote
I think you should try the 5 tube/variac setup. At the end of the other thread there is a diagram of the wiring using 2 capacitors to provide the ground connection. [/quote]

I have looked at that several times and still cannot make out the values of the two capacitors. I have also tried to find the original online with no joy.

Sure hope that the weather is better down there than it is up here in Iowa....in the fifties and rainy here. :(

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 3:54 am 
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There is a danger in using a 6V battery or transformer with a dropping resistor. If one of the tubes should fail, be loose in it's socket, have a bad connection, the voltage on the rest of the tubes will increase. Certainly don't try it with just one tube; there will be close to the whole 6V across the heater. Modern tubes can stand double voltage for a while but I have no idea if your antique ones will.

I wouldn't use the variac either. Accidentally bump the knob and your tubes are history.

Either start out with a 3V supply, use a transformer that delivers 3V, or use a regulator that delivers 3V and isn't likely to be misadjusted by accident.

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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 4:56 am 
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+1 on Jim's post!
73,
-marc


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 5:57 am 
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jrehkopf wrote:
You have to read those q&a carefully. Some of them didn’t know to take the paper off the plexiglas cover. Mine is the 12 amp version, I figured it is good for half that. I liked the volt/amp readout. I mentioned it because I know it works up to 4 amps and does not make noise. Just my experience.

I think you should try the 5 tube/variac setup. At the end of the other thread there is a diagram of the wiring using 2 capacitors to provide the ground connection.


Jeff, I saw that question about not realizing there was paper on the plexiglass...some people should not be in the gene pool. :)

Tonight was a completely different experience with the radio. Now I am not sure that my current power supply is causing any problem to speak of. When I first tried the radio with my current power supply I actually got a couple of stations (first time ever) on the very low end of the dial scale. Unfortunately, the stations were on top of each other and very garbled. There was some noise in it but not near like it was before. That radio is so "touchy" that if I touch anything, even the face, I get static, the station fades out, etc. I think that I need to go back to square one and clean every tube pin, check the coils, etc. and even re-solder some of the joints.

I did try my 4.75 amp variac set exactly on three volts with only five 1 amp tubes and promptly blew the fuse in the variac. That also happened a couple of weeks ago when I tried it with all six tubes in place. It seems that anything that draws over the stated 4.75 amps pops the fuse. With my original power supply hooked up I disconnected one tube and it made absolutely no difference...still had the garbled two stations.

Thanks for all of your help and stay well,

Don


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