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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 2:10 am 
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Now the B+ is 284V unloaded. I will simulate a load and see what it is. Seems to be purring along now. I will also wire the heaters.
So if we keep on adding cap-diode stages, we can get up to 2.1.gigawatts? Then I could go back in time and warn my Mom about me.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 2:40 am 
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john8750 wrote:
Now the B+ is 284V unloaded. I will simulate a load and see what it is. Seems to be purring along now. I will also wire the heaters.
So if we keep on adding cap-diode stages, we can get up to 2.1.gigawatts? Then I could go back in time and warn my Mom about me.
My sim shows 277 V unloaded. Your 284 V is only 2.5% higher so that's very good agreement.

Up to 2.1 giga -->VOLT<-- , not Watt. The total Watt remain the same so as voltage is increased current goes down by the same ratio. In reality, leakages will limit the voltage because, sooner or later, they'll be as large as the current capability. Plus, 2.1 gigavolt caps are hard to find. :wink:


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 3:40 am 
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Flipperhome wrote:
john8750 wrote:
Now the B+ is 284V unloaded. I will simulate a load and see what it is. Seems to be purring along now. I will also wire the heaters.
So if we keep on adding cap-diode stages, we can get up to 2.1.gigawatts? Then I could go back in time and warn my Mom about me.
My sim shows 277 V unloaded. Your 284 V is only 2.5% higher so that's very good agreement.

Up to 2.1 giga -->VOLT<-- , not Watt. The total Watt remain the same so as voltage is increased current goes down by the same ratio. In reality, leakages will limit the voltage because, sooner or later, they'll be as large as the current capability. Plus, 2.1 gigavolt caps are hard to find. :wink:





Well, Dr Brown says gigawatts. :lol:
B+ loaded with 15.15K ohms is 260volts. Is that OK?
Got my BT labs box today. It looks good. A very small tranny, two tubes. Should I strip out everything? Can we build any transmitter using that transformer? I paid $20 for it with free shipping. It seems to be in remarkably good shape, no back. The guy paid $18.05 to ship it. So he made $1.95 on the deal. I realize that we need to finish the amp first.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 4:22 am 
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Seems the BT Labe transformer is only 125ma. Think I will keep an eye on a Mallory box, AKA Gort. I got a copy of the schematic. Tubes are 6A4F and 6AB4. Are they any use to us for a transmitter or receiver? Thank you Flip....

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 4:42 am 
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john8750 wrote:
Flipperhome wrote:
My sim shows 277 V unloaded. Your 284 V is only 2.5% higher so that's very good agreement.

Up to 2.1 giga -->VOLT<-- , not Watt. The total Watt remain the same so as voltage is increased current goes down by the same ratio. In reality, leakages will limit the voltage because, sooner or later, they'll be as large as the current capability. Plus, 2.1 gigavolt caps are hard to find. :wink:
Well, Dr Brown says gigawatts. :lol:
B+ loaded with 15.15K ohms is 260volts. Is that OK?
Got my BT labs box today. It looks good. A very small tranny, two tubes. Should I strip out everything? Can we build any transmitter using that transformer? I paid $20 for it with free shipping. It seems to be in remarkably good shape, no back. The guy paid $18.05 to ship it. So he made $1.95 on the deal. I realize that we need to finish the amp first.
Doc Brown was talking about the POWER it took and he was right to say gigawatt. I was talking about a voltage multiplier and you aren't going to get any more 'watts' than is there out of the transformer, much less 2.1 gigawatt.

15.51K is fine and is loading a little more (17mA) than the expected final circuit (14mA) will. Of course, you don't have the heater load and that will bring B+ down some more, maybe 7 or 8 Volt.

Btw, my model is based on a 36VCT 12 Watt transformer I have so it should predict a little low due to higher winding resistance. But for circuits like this it doesn't matter if we're off by 10 or 20 volt one way or the other. If fact, it doesn't matter if we're off by 50 V. The tubes aren't operating at or near max plate dissipation at all.

Unless you want to keep it as a UHF converter you might as well gut it.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 4:44 am 
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john8750 wrote:
Seems the BT Labe transformer is only 125ma. Think I will keep an eye on a Mallory box, AKA Gort. I got a copy of the schematic. Tubes are 6A4F and 6AB4. Are they any use to us for a transmitter or receiver? Thank you Flip....
How did you come to that conclusion? You must be mistaking the B+ voltage rating for heater current because the two tubes comes to 405mA.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 5:23 am 
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Flipperhome wrote:
john8750 wrote:
Seems the BT Labe transformer is only 125ma. Think I will keep an eye on a Mallory box, AKA Gort. I got a copy of the schematic. Tubes are 6A4F and 6AB4. Are they any use to us for a transmitter or receiver? Thank you Flip....
How did you come to that conclusion? You must be mistaking the B+ voltage rating for heater current because the two tubes comes to 405mA.





The total wattage on the name plate says 15watt, so I calculated 125ma.
I forgot just what schematics we have considered so far. But like this one.
Attachment:
Two Tube schematic.jpg
Two Tube schematic.jpg [ 46.79 KiB | Viewed 1927 times ]

What do you think? I am going for the Mallory box with the rectifier tube, for a housing.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 5:48 am 
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john8750 wrote:
Flipperhome wrote:
john8750 wrote:
Seems the BT Labe transformer is only 125ma. Think I will keep an eye on a Mallory box, AKA Gort. I got a copy of the schematic. Tubes are 6A4F and 6AB4. Are they any use to us for a transmitter or receiver? Thank you Flip....
How did you come to that conclusion? You must be mistaking the B+ voltage rating for heater current because the two tubes comes to 405mA.
The total wattage on the name plate says 15watt, so I calculated 125ma.
You calculated the equivalent draw on the AC line. (I say 'equivalent' because it isn't a sine wave.) But the heaters are at 6.3 V, not 120V, and you don't really know what B+ is at (probably between 130 V and 160 V). In short, you didn't calculate heater current but you know for darn sure it has to power the two tubes inside, which come to 405 mA.
john8750 wrote:
I forgot just what schematics we have considered so far. But like this one.
Attachment:
Two Tube schematic.jpg

What do you think? I am going for the Mallory box with the rectifier tube, for a housing.
It's a nice transmitter but takes 800 mA for the 6888 tube alone and it isn't tunable.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 6:27 am 
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Flipperhome wrote:
]It's a nice transmitter but takes 800 mA for the 6888 tube alone and it isn't tunable.

Yeah it's fixed at the middle of the broadcast band at 1 Mhz. (unless you also can find another xtal at some other good AM band freq)
So John... all you need to do is check that there are no other strong competing AM radio stations on 1Mhz (1000khz) in your town or nearby area.

If the 1000khz spot on you local AM dial is free you'll have no problems.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 6:49 am 
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Pbpix wrote:
Flipperhome wrote:
]It's a nice transmitter but takes 800 mA for the 6888 tube alone and it isn't tunable.

Yeah it's fixed at the middle of the broadcast band at 1 Mhz. (unless you also can find another xtal at some other good AM band freq)
So John... all you need to do is check that there are no other strong competing AM radio stations on 1Mhz (1000khz) in your town or nearby area.

If the 1000khz spot on you local AM dial is free you'll have no problems.



Good idea Peter. Where I live, Banning, there is very weak radio on both AM and FM. I will check the 1000KHZ dial when I go back home next week.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 6:53 am 
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t's a nice transmitter but takes 800 mA for the 6888 tube alone and it isn't tunable.

So if we choose that one, I will replace the transformer. Or we can settle on a tunable set. I don't know.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 7:54 am 
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john8750 wrote:
t's a nice transmitter but takes 800 mA for the 6888 tube alone and it isn't tunable.

So if we choose that one, I will replace the transformer. Or we can settle on a tunable set. I don't know.
If you want to go that route I'd suggest the 6GY6 version, which has a 450 mA heater. The 6888 is just too much tube.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 8:20 am 
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For that matter the 6sa7 is only 300maand the 12sa7 is 150ma:
ref: http://www.electronixandmore.com/projects/amxmitter/

Image

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 7:29 pm 
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Pbpix wrote:
For that matter the 6sa7 is only 300maand the 12sa7 is 150ma:
ref: http://www.electronixandmore.com/projects/amxmitter/

Image




Thanks for the ideas Men. I want to get the Mallory converter, has a bigger transformer and looks much better. I am looking at the 3 tube version. It had a tube rectifier so the power transformer should be at max output, according to Flip. A tunable transmitter would be better, I guess and still don't know.
Peter, would there be a problem with grounds being that this circuit is not isolated?

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 06, 2017 8:13 pm 
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john8750 wrote:
Pbpix wrote:
For that matter the 6sa7 is only 300maand the 12sa7 is 150ma:
ref: http://www.electronixandmore.com/projects/amxmitter/

Image

Thanks for the ideas Men. I want to get the Mallory converter, has a bigger transformer and looks much better. I am looking at the 3 tube version. It had a tube rectifier so the power transformer should be at max output, according to Flip. A tunable transmitter would be better, I guess and still don't know.
Peter, would there be a problem with grounds being that this circuit is not isolated?
You know my opinion of direct AC line connections when there are external inputs/outputs. One mistake, whether by you or some yahoo that wired your AC, and you're directly across the AC line. It isn't safe.

The 6/12SA7 is remote cutoff and not terribly linear. The 12CS6 is a sharp cutoff heptode and will be a lot more linear. Try this one viewtopic.php?f=12&t=132867


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sat 07, 2017 1:19 am 
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I like it Flip. Is that transformer still available? If we decide on that one, I will pre order the transformer, and tubes.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sat 07, 2017 1:24 am 
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All tube heaters are wired. I am getting +/-42volts on each filament string. And a B+ of 252volts. I like it so far.
Here is another dumb question. Will it hurt to wire the circuits while the tubes are inserted into the sockets? I am guessing no.
Would any of you guys like the tube boxes? Let me know as I don't collect them.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sat 07, 2017 1:59 am 
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john8750 wrote:
I like it Flip. Is that transformer still available? If we decide on that one, I will pre order the transformer, and tubes.
No, it's not. But you could use the transformer in the BTU-2S, except it's B+ will, no doubt, be different and then you'd have to deal with setting up the screen grid and bias for the new voltages.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sat 07, 2017 2:10 am 
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john8750 wrote:
All tube heaters are wired. I am getting +/-42volts on each filament string. And a B+ of 252volts. I like it so far.
Here is another dumb question. Will it hurt to wire the circuits while the tubes are inserted into the sockets? I am guessing no.
Would any of you guys like the tube boxes? Let me know as I don't collect them.
That's 5% high. Probably okay. What voltage is your AC line running at?

I don't think it's a good idea to wire with the tubes inserted in the sockets. If everything goes right it should be okay but one slip and solder can wick up the socket pins and then you've got the tube pin soldered into the socket.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sat 07, 2017 2:30 am 
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Flipperhome wrote:
john8750 wrote:
All tube heaters are wired. I am getting +/-42volts on each filament string. And a B+ of 252volts. I like it so far.
Here is another dumb question. Will it hurt to wire the circuits while the tubes are inserted into the sockets? I am guessing no.
Would any of you guys like the tube boxes? Let me know as I don't collect them.
That's 5% high. Probably okay. What voltage is your AC line running at?

I don't think it's a good idea to wire with the tubes inserted in the sockets. If everything goes right it should be okay but one slip and solder can wick up the socket pins and then you've got the tube pin soldered into the socket.




Wow Flip, I never thought about that. Glad I asked.
House AC is 121volts. Remember that my dummy load is still 150ohms light, if that matters.

I didn't like the looks of that transformer anyway, for the transmitter. I do like the circuit.

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