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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Thu 19, 2017 12:07 am 
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john8750 wrote:
I received my Mallory UHF tuner box today. It has two 7pin sockets, and a good transformer. The case is in good shape, with not the original knobs, but they look OK. Flip, are there any usable components on board? Or is it all just scrap? I will use it for the two tube AM transmitter. Could the transformer be used, od should I get a new one?
This is the transmitter I will build.
viewtopic.php?f=12&t=132867&start=560
Soon as I get my shop in shape, next week, I will start testing the Little Prince.
That transmitter should fit the Mallory just fine except for, since the transformer has 6.3VAC for the heaters, using 6.3 VAC tubes instead of the shown 12.6 VAC tubes. Then it'll have to be tweaked to accommodate whatever B+ comes out as.

You never know what someone might find useful but I didn't.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Thu 19, 2017 12:46 am 
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Pbpix wrote:
john8750 wrote:
I received my Mallory UHF tuner box today. It has two 7pin sockets, and a good transformer. The case is in good shape, with not the original knobs, but they look OK. Flip, are there any usable components on board? Or is it all just scrap? I will use it for the two tube AM transmitter. Could the transformer be used, od should I get a new one?
This is the transmitter I will build.
viewtopic.php?f=12&t=132867&start=560
Soon as I get my shop in shape, next week, I will start testing the Little Prince.

Is the schematic shown on the 1st page of that 30 page thread the final version?



It is peter. I have a kit coming for the transmitter. Looks like fun. Like you guys pointed out, I do have a station on 1MHZ. But it is weak. Wont be a problem inside with my transmitter operating. I would like to use the transformer on the Mallory chassis if possible. Not sure if the kit has a transformer.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Thu 19, 2017 12:48 am 
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Flipperhome wrote:
john8750 wrote:
I received my Mallory UHF tuner box today. It has two 7pin sockets, and a good transformer. The case is in good shape, with not the original knobs, but they look OK. Flip, are there any usable components on board? Or is it all just scrap? I will use it for the two tube AM transmitter. Could the transformer be used, od should I get a new one?
This is the transmitter I will build.
viewtopic.php?f=12&t=132867&start=560
Soon as I get my shop in shape, next week, I will start testing the Little Prince.
That transmitter should fit the Mallory just fine except for, since the transformer has 6.3VAC for the heaters, using 6.3 VAC tubes instead of the shown 12.6 VAC tubes. Then it'll have to be tweaked to accommodate whatever B+ comes out as.

You never know what someone might find useful but I didn't.



Good. When I get to building the transmitter I will scrap the innards.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Thu 19, 2017 2:17 am 
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john8750 wrote:
Hey Flip. That is just amazing. I read that article, and thought it made since. Until I applied your logic. I had to study hard to understand. Man, what an education. You should be teaching this theory. It sure would clear up some confusion.
Thanks. I'm convinced that the motive behind increasing sensitivity is driven by the proliferation of battery powered devices with, seemingly, ever decreasing output. But "legacy" devices?

Take the Shure M-65 tube RIAA preamp, surely a "legacy" device. It's RIAA gain is 44 dB rated at 760 mV out for a 5 mV input (output will vary with the cartridge used). In digital 'FSO' speak that corresponds to 4.8 Volt! That's hardly the puny output claimed by the article.

The Shure 'transistor' M-61 of the same thing has a gain of 46 producing 1V at 5 mV input, which is a little over 6 V in digital speak.

By the same token, a 'modern' Behringer PP400 phono preamp has a gain of 35 for 280 mV out at 5 mV input. More expensive units have 40 dB for 500 mV at 5 mV input (since Prince John has a 'modern' level of sensitivity this was my target for the RIAA preamp and SPICE came out at 39 dB).

Btw, a 26 buck Audio Technica cartridge has 5 mV output while a $1500 'Reference Series' Grado Cartridge has 4mV and a causal perusal of cartridges came up with a low of 3.5 mV so the corresponding preamp output can vary considerably depending on what cartridge is used.

That doesn't even get down to how 'hot' the record is cut (you can pack more music per inch if you make the groves smaller, meaning less amplitude).

Such a seemingly 'simple' thing as volume get's quite complex rather quickly.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Thu 19, 2017 9:44 pm 
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In the middle of moving now. I will be back to the preamp soon. Flip, is the 12av6 filament split for 6volts? If so, will it need 300ma? Just wondering if the transformer on the Mallory will work.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Thu 19, 2017 9:57 pm 
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john8750 wrote:
In the middle of moving now. I will be back to the preamp soon. Flip, is the 12av6 filament split for 6volts? If so, will it need 300ma? Just wondering if the transformer on the Mallory will work.

12av6 is 150ma
You have my unrestricted and unlimited permission to use this site forever and always to look up all or any tube specs yourself Sir John.
http://nj7p.org/Tubes/SQL/Tube_query.php?Type=12Av6

ImageImage

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 12:09 am 
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Pbpix wrote:
john8750 wrote:
In the middle of moving now. I will be back to the preamp soon. Flip, is the 12av6 filament split for 6volts? If so, will it need 300ma? Just wondering if the transformer on the Mallory will work.

12av6 is 150ma
You have my unrestricted and unlimited permission to use this site forever and always to look up all or any tube specs yourself Sir John.
http://nj7p.org/Tubes/SQL/Tube_query.php?Type=12Av6

ImageImage



Thank you master. I appreciate that site and will keep it. So can the 12AV6 be powered with 6 volts :?:

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 12:57 am 
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john8750 wrote:
Pbpix wrote:
john8750 wrote:
In the middle of moving now. I will be back to the preamp soon. Flip, is the 12av6 filament split for 6volts? If so, will it need 300ma? Just wondering if the transformer on the Mallory will work.

12av6 is 150ma
You have my unrestricted and unlimited permission to use this site forever and always to look up all or any tube specs yourself Sir John.
http://nj7p.org/Tubes/SQL/Tube_query.php?Type=12Av6

ImageImage



Thank you master. I appreciate that site and will keep it. So can the 12AV6 be powered with 6 volts :?:

OMG... lol .... didn't you go to that page and READ the specs John? .. That's why I gave you THAT link... so you'd go there and READ it.


"Heater Voltage ................................ 12.6 V
Heater Current ................................ 0.15 A"

Image

If you want to use 6v use the 6av6 but that requires 300ma.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 1:16 am 
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john8750 wrote:
In the middle of moving now. I will be back to the preamp soon. Flip, is the 12av6 filament split for 6volts? If so, will it need 300ma? Just wondering if the transformer on the Mallory will work.
No, neither the tubes nor the heater winding can be 'split'. The voltage is the voltage. You have to buy the 6.3V versions instead of the 12.6V versions.

The two tubes will pull 600mA, which is 75mA more than the original tubes 525mA but the lower B+ current draw should make up for it.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 1:46 am 
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I went there Peter. I saw the 12av6 with a 12 volt heater. But I thought there was a split tap for powering with 6 volts. The other tube is 12cs6. I don't see the B+ current draw on the transmitter schematic Flip, so will figure it later. Thanks Men.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 2:23 am 
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john8750 wrote:
I went there Peter. I saw the 12av6 with a 12 volt heater. But I thought there was a split tap for powering with 6 volts. The other tube is 12cs6. I don't see the B+ current draw on the transmitter schematic Flip, so will figure it later. Thanks Men.
You won't find B+ draw listed for the Mallory either. My "should work" is just a gut feel.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 2:35 am 
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john8750 wrote:
I went there Peter. I saw the 12av6 with a 12 volt heater. But I thought there was a split tap for powering with 6 volts. .

But John, if you went there and saw the drawing you could see there isn't any filament tap.... right?
Did you see that drawing?
Image



now here's a 12at7 with a tapped filament.... do you see the difference?
Image

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 3:57 am 
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This a clash of the Titans. peter says no, Flip says yes, John is confused.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 4:25 am 
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john8750 wrote:
This a clash of the Titans. peter says no, Flip says yes, John is confused.

No, the 12AT7 is NOT the 12AV6.

The 12AT7, 12AX7, 12AU7, 12AY7, and 12AZ7 (any tube with a 9A base) DOES have a center tap.

The 12AV6 not only isn't a 9A base, it's not even a 9 pin tube. It's a 7 pin and there's no spare pin to put a heater center tap. It simply can't be done.

You have to use the 6AV6 for a 6.3VAC heater.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 4:35 am 
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Flipperhome wrote:
john8750 wrote:
This a clash of the Titans. peter says no, Flip says yes, John is confused.

No, the 12AT7 is NOT the 12AV6.

The 12AT7, 12AX7, 12AU7, 12AY7, and 12AZ7 (any tube with a 9A base) DOES have a center tap.

The 12AV6 not only isn't a 9A base, it's not even a 9 pin tube. It's a 7 pin and there's no spare pin to put a heater center tap. It simply can't be done.

You have to use the 6AV6 for a 6.3VAC heater.




The sun comes shining through. I see, by the light of the silvery moon. :lol:

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Fri 20, 2017 6:26 pm 
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I located the 6AV6 and the 6CS6, and will get them if necessary.

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sun 22, 2017 5:44 am 
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The transmitter kit does have the original transformer included. So that project is ready to go.

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If I did something right, I made a mistake.


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sun 22, 2017 6:01 am 
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john8750 wrote:
The transmitter kit does have the original transformer included. So that project is ready to go.
So you can just use the enclosure.

Someday you really must get around to trying the preamp. :wink:


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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sun 22, 2017 7:40 am 
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:arrow:
Flipperhome wrote:
john8750 wrote:
The transmitter kit does have the original transformer included. So that project is ready to go.
So you can just use the enclosure.

Someday you really must get around to trying the preamp. :wink:




The tube sockets, chassis, enclosure, and line cord will be vintage anyway.
The preamp is first thing on my list Flip. I have a rain delay for moving right now, wont be much longer now. Believe me, the preamp is on my itty bitty brain like gum on my shoe. :arrow:

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 Post subject: Re: PRINCELY PAUPER
PostPosted: Jan Sun 22, 2017 8:25 am 
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john8750 wrote:
:arrow:
Flipperhome wrote:
john8750 wrote:
The transmitter kit does have the original transformer included. So that project is ready to go.
So you can just use the enclosure.

Someday you really must get around to trying the preamp. :wink:
The tube sockets, chassis, enclosure, and line cord will be vintage anyway.
The preamp is first thing on my list Flip. I have a rain delay for moving right now, wont be much longer now. Believe me, the preamp is on my itty bitty brain like gum on my shoe. :arrow:
I swapped mine for a grounded 3 prong plug which, as noted in my Gort "features" list, has a 3 pin AC socket molded on top of the plug so you don't lose an outlet.

If you're anything like me your head must be ready to explode from having to wait :shock:


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