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 Post subject: My AA5 Homebrew / Trainer
PostPosted: Nov Sun 06, 2016 11:35 pm 
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I have been working on old radios for over 4 years, and although I have learned a lot (much of that from ARF) I wanted to get a better understanding of components and how they function in a radio circuit.

To help my learning, have started to build an AA5 radio/trainer. The idea is to have a simple working superhet radio that I can change components on and experiment with. I do not expect the radio to be great performer, nor win any awards for beauty :D

I first laid out a diagram on paper of where I would locate components. My designs changed several times after experimenting with different chassis and mounting techniques. Ultimately, I came up with what you see in the photos below. My first step was to lay out the tubes, power switch and lamp, then assemble and check the filament string.
After having done that, I added components to make the B+. I admit to being a bit nervous when I powered it on, and very happy when it came on with a measurement of 157 VDC.

I will update this thread with more photos and comments as I continue.

Russ


Attachments:
File comment: Tubes, switch, and lamp only.
RT_R1 copy.jpg
RT_R1 copy.jpg [ 131.45 KiB | Viewed 1621 times ]
File comment: B+ Added
RT_R3 copy.jpg
RT_R3 copy.jpg [ 137.34 KiB | Viewed 1621 times ]

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 1:11 am 
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What a nifty project!

I look forward to following your experiment.

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 2:43 am 
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Russ,

This is a great idea, as even someone who would be considered fairly experienced will be able to view circuit dynamics in what could be considered 'block diagram form'. Definitely a great way to brush up on theory!

Please make and upload a video (series, maybe?) demonstrating the results, trials and tribulations of working the bugs out of the initial version of the build, and the lessons learned during circuit modification.

Tim

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 2:45 am 
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WoodchuckTN wrote:
What a nifty project!

I look forward to following your experiment.

+1!

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 4:43 am 
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Pretty neat! You could also stick in a fuse or two.

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 6:01 am 
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Looking good! In the future you can use octal relay socket to make swapping out components easier to experiment with.

Sal

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 6:18 am 
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Sal Brisindi wrote:
Looking good! In the future you can use octal relay socket to make swapping out components easier to experiment with.

Sal


Still time to do it, Mouser has them http://www.mouser.com/search/ProductDet ... ey70-464-1

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 6:48 am 
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Even cheaper: http://www.ebay.com/itm/New-8-Round-Pin ... Sw6n5Xq0NF

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 8:20 am 
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BikenSwim wrote:
Sal Brisindi wrote:
Looking good! In the future you can use octal relay socket to make swapping out components easier to experiment with.

Sal


Still time to do it, Mouser has them http://www.mouser.com/search/ProductDet ... ey70-464-1

Nice socket.
But why were these made for use with relays?
Why couldn't the relay just plug into any regular octal socket and be wired up like a tube?

What am I missing?

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 3:25 pm 
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Pbpix wrote:
BikenSwim wrote:
Sal Brisindi wrote:
Looking good! In the future you can use octal relay socket to make swapping out components easier to experiment with.

Sal


Still time to do it, Mouser has them http://www.mouser.com/search/ProductDet ... ey70-464-1

Nice socket.
But why were these made for use with relays?
Why couldn't the relay just plug into any regular octal socket and be wired up like a tube?

What am I missing?


Socketed relays are often used in machine control cabinets and such. They are usually surface mounted and then point to point wired.


Larry


Attachments:
relays.PNG
relays.PNG [ 224.98 KiB | Viewed 1462 times ]
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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 5:36 pm 
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Pbpix wrote:

Why couldn't the relay just plug into any regular octal socket and be wired up like a tube?

What am I missing?


For industrial use they make up wiring harnesses with crimp spade connectors to connect to the socket screw terminals. Making a change is easier than unsoldering and resoldering and so is replacement of the socket. The other standard is to use DIN rails rather than surface mount directly.

For a prototype project this makes good sense to me because you can break a connection, take a reading and then reconnect the wire with very little effort. I could even see putting all resistors and capacitors on terminal strips with screw terminals for similar reasons.

Kind of like a Radio Shack electronics 10 in 1 lab...... except with very hot components and lethal voltages! :-)

Very cool project! My only suggestion would be to skip the AA5 and go to a basic superhet with 12v filament string. This would make swapping and experimenting with different tubes easier. It also removes the 110v line from your tubes.

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 6:58 pm 
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Very cool! A home-built RCA Dynamic Demonstrator, for a small fraction of the cost. I would love to have the same sort of setup to simulate common radio faults to the members of our antique radio club that are just getting started in the hobby. I look forward to seeing the results of your progress!

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 9:59 pm 
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black85vette wrote:
My only suggestion would be to skip the AA5 and go to a basic superhet with 12v filament string. This would make swapping and experimenting with different tubes easier. It also removes the 110v line from your tubes.

Interesting thought, but he would get more learning mileage using an AA5 type of circuit, with it's normal tube lineup.
Perhaps adding a power transformer would offer reasonable shock protection?

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Mon 07, 2016 10:16 pm 
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fifties wrote:
black85vette wrote:
My only suggestion would be to skip the AA5 and go to a basic superhet with 12v filament string. This would make swapping and experimenting with different tubes easier. It also removes the 110v line from your tubes.

Interesting thought, but he would get more learning mileage using an AA5 type of circuit, with it's normal tube lineup.
Perhaps adding a power transformer would offer reasonable shock protection?


A center-tapped 12.6 volt transformer would allow trying any mix of 6 or 12 volt tubes on hand.
There is a 12L6 version of the 50L6, and 12X5 rectifier for example. An isolation transformer for B+ and you would be able to try anything. eBay has cheap Chinese eye tubes for 7 pin miniature sockets, and all kinds of small digital panel meters.

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Tue 08, 2016 1:46 am 
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Image

When working on a AA5 I still refer to this when I am stumped.

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Tue 08, 2016 2:19 am 
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That's a great idea, but please use an isolation transformer with this.


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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Tue 08, 2016 3:05 am 
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Sal Brisindi wrote:
Looking good! In the future you can use octal relay socket to make swapping out components easier to experiment with.

Sal


Interesting thought! I tried a few ideas before I settled on the one shown, including putting the tubes upside down underneath the board so the sockets would be up. Really no different than tipping a chassis over I suppose.
In any case the octal relay base is a cool idea, though I think at this point I will leave things as they are. I will need to find a way of making temporary connections for component swapping.

Russ

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Tue 08, 2016 3:08 am 
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Scottb wrote:
Image

When working on a AA5 I still refer to this when I am stumped.


Wow! That is very cool, I bet there were many of those made for training back in the day. Probably not too many left.

Russ

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Tue 08, 2016 3:10 am 
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BobWeaver wrote:
That's a great idea, but please use an isolation transformer with this.


Yup absolutely! I may take Number 6's advice and install a fuse also.

Russ

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 Post subject: Re: My AA5 Homebrew / Trainer
PostPosted: Nov Tue 08, 2016 3:28 am 
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Pbpix wrote:
BikenSwim wrote:
Sal Brisindi wrote:
Looking good! In the future you can use octal relay socket to make swapping out components easier to experiment with.

Sal


Still time to do it, Mouser has them http://www.mouser.com/search/ProductDet ... ey70-464-1

Nice socket.
But why were these made for use with relays?
Why couldn't the relay just plug into any regular octal socket and be wired up like a tube?

What am I missing?
The convenience of screw terminals to change things and experiment. Like this one I did when experimenting with octal battery tubes.

Attachment:
Batman BB sm.jpg
Batman BB sm.jpg [ 105.02 KiB | Viewed 1329 times ]


Not exactly pretty but it worked.

For 9 and 7 pin I made these up from old scrap terminal PC boards.

Attachment:
FM Xmitter  w-6AU6 Preamp3a.jpg
FM Xmitter w-6AU6 Preamp3a.jpg [ 109.13 KiB | Viewed 1329 times ]


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