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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old Yesterday, 1:52 pm   #41
ms660
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Default Re: First Radio Build - 12V HT system

There's three connections to the pot, the pot will have three tags, the center tag is the wiper (black arrow in the schematic) the two outer tags are the track (50k in the schematic) The regen pot in the schematic is configured as a potential divider, the track is connected across the supply, one end to the 12 volts +ve rail, the other end to chassis/ground rail which is also the -ve of the supply voltage. The slider connects to the 100k resistor.

Lawrence.
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Old Yesterday, 2:24 pm   #42
bobskie
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Default Re: First Radio Build - 12V HT system

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Originally Posted by ms660 View Post
There's three connections to the pot, the pot will have three tags, the center tag is the wiper (black arrow in the schematic) the two outer tags are the track (50k in the schematic) The regen pot in the schematic is configured as a potential divider, the track is connected across the supply, one end to the 12 volts +ve rail, the other end to chassis/ground rail which is also the -ve of the supply voltage. The slider connects to the 100k resistor.

Lawrence.
Stupid mistake, I didn't see the 12V line somehow. I'll get a picture of the board up when I finish it.
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Old Yesterday, 6:32 pm   #43
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Default Re: First Radio Build - 12V HT system

I wound the coil a second ago but some wires are crossed over and there are some gaps in between. Will this still work ok or should I start again?

Cameron
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Old Yesterday, 8:58 pm   #44
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Default Re: First Radio Build - 12V HT system

It'll probably work; but will you ever be truly happy, knowing you might have been able to wind that coil more neatly?

Don't rip your first effort apart, though; make a new former for your second attempt, just in case it's no better than the first.
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Old Yesterday, 10:24 pm   #45
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Default Re: First Radio Build - 12V HT system

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It'll probably work; but will you ever be truly happy, knowing you might have been able to wind that coil more neatly?

Don't rip your first effort apart, though; make a new former for your second attempt, just in case it's no better than the first.
That's true, I'll give it another go at some point but I'll probably just test it out with this one. Winding that wire is a bit of a pain. I ended up breaking off the tap as well so I had to solder it back on, not a particularly neat job

Cameron
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Old Today, 10:41 am   #46
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Default Re: First Radio Build - 12V HT system

Another question! What are those connections on the valve like the ones with the number 9 that seemingly go nowhere? I have attached another diagram with a non transparent background.

Cameron
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Old Today, 10:51 am   #47
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Default Re: First Radio Build - 12V HT system

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Another question! What are those connections on the valve like the ones with the number 9 that seemingly go nowhere? I have attached another diagram with a non transparent background.

Cameron
That's because pin 9 isn't connected to anything when the heaters are connected for 12.6 volt operation.

Remember that the ECC82 valve heaters can be connected for 6.3 volt or 12.6 volt operation.

For 6.3 volt operation pins 4 and 5 are connected together, the heater supply is then connected to that connection and pin 9.

When connected for 12.6 volt operation the heater current will be half current that is drawn when they are connected for 6.3 volt operation:

http://www.r-type.org/pdfs/ecc82.pdf

Lawrence.
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