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 Post subject: Building a 6LE8 Transmitter
PostPosted: Oct Mon 13, 2014 5:47 pm 
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Location: Puyallup WA
I'm a newbie to the forum and to the hobby & trying to learn all I can.

I'm getting ready to build the 6LE8 transmitter that has been documented so well here. Right now I'm in the process of sourcing all the parts but I'm getting stuck on the "safety capacitors". I see on the parts list these need to be .0047 uF but can someone go into further detail on these? I'm not 100% sure on what I should be buying here.

Thanks everyone. Love this forum

-Dave

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Tue 14, 2014 11:12 am 
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Hi, you have to search for X and Y capacitors . X is across the line and Y is line yo ground. some caps can do both. Here`s some at Mouser.

http://www.mouser.com/ProductDetail/Kem ... kVDT3p8%3d

http://www.mouser.com/ProductDetail/Kem ... 252bEYs%3d

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Tue 14, 2014 10:13 pm 
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That helps! Thanks again.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Mon 05, 2015 6:58 pm 
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OK so I'm FINALLY at the point where I'm starting to put components down on the board for this. Looking at the schematic, there are a couple things i'm trying to understand.

Am I reading it right where it's showing the B+ going into the tank circuit?

The other thing I'm struggling to understand is how TR2 is wired. It shows the secondary from TR1 going to the secondary of TR2? So the voltage is stepping down on TR1 then stepping back up on TR2 ?

Can someone elaborate on these so I can better understand? The whole purpose of my building this is to learn so here I go!

-dave

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Mon 05, 2015 7:22 pm 
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Location: aston, pa, usa
Can you post the schematic on here for all to see?

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Mon 05, 2015 8:31 pm 
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This one, maybe?

viewtopic.php?t=83489

Colin


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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Mon 05, 2015 8:47 pm 
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This is the one I was referring to..


Attachments:
6l38.pdf [40.91 KiB]
Downloaded 123 times

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Mon 05, 2015 8:48 pm 
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Yea thanks Colin. That's the instructions set I'm using.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Wed 07, 2015 12:34 am 
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Am I reading it right where it's showing the B+ going into the tank circuit?
------------------------------------------------------------------------------------------------
yes

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Wed 07, 2015 12:49 am 
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So the voltage is stepping down on TR1 then stepping back up on TR2 ?
---------------------------------------------------------------------------------------------
Yes, however in the middle of it all it's stealing 6.3v just to power the tube filament. The whole thing with both transformers is just for isolation.

The long story: TR-1's primary is 120v. Qty of 2, 6.3v secondary windings on TR-1. One of the two is dedicated to the tube heater. The other TR-1 secondary goes to TR-2. TR-2 uses it's 6.3v side as it's primary. It puts both 6.3 windings in parallel. So, 6.3v is the primary voltage for TR-2. The 120v side of TR-2 is TR-2's secondary. So, yes in the big picture 120v goes in and 120v comes out just for isolation.

EDIT: It looks like pins 4 & 5 are the heater pins for the 6LE8 tube.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Wed 07, 2015 12:58 am 
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B+ to the tank circuit?--yes, that's what the schematic shows.

2 transformers?---someone's just being clever. Filament transformers are cheap. Just as good to use one transformer for both filament and high-voltage. (I'd be using whatever parts were on hand---modifying the circuit as required)

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Wed 07, 2015 1:01 am 
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The whole purpose of my building this is to learn so here I go!
-------------------------------------------------------------------------------
Keep asking away. Someone on here will have an answer for you.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Wed 07, 2015 1:08 am 
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(I'd be using whatever parts were on hand---modifying the circuit as required)
--------------------------------------------------------------------------------------------------
Yea, many members on here will homebrew something by using whatever is at hand in their junk box. So, many different transformer configurations could also be used for the 6LE8 broadcaster, but using two filament transformers is clever and cheap especially if buying new store bought tranny's.

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Last edited by bill hamre on Oct Thu 08, 2015 6:35 pm, edited 2 times in total.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Thu 08, 2015 5:04 pm 
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BTW, I think the sylania 6LE8 tube out performed others in 6LE8 broadcasters back in the day. 35Z5 will remember the details. It might have been certain vintage sylvania.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Thu 08, 2015 6:16 pm 
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Joined: Oct Mon 13, 2014 5:25 pm
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Thanks so much everyone for all the great info. One of the last things I need for the project is the tube itself. I have a great local resource for tubes Bill & I can inquire about what you mention on the Sylvanias.
I hope to post some pics when I start assembling.. should be this weekend!

-Dave

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Thu 08, 2015 6:27 pm 
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Location: aston, pa, usa
I just sent my 6LE8 tubes to Colin A. I'm trying to contact 35Z5 to see about vintage of sylvania. Don't remember if I sent Colin A any sylvania or not.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Mon 19, 2015 11:58 pm 
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Joined: Oct Mon 13, 2014 5:25 pm
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Location: Puyallup WA
Got a shiny new (to me) Sylvania 6LE8 in the mail today! Thanks again Bill and Colin I sure do appreciate that!

I haven't made enough progress yet worthy of taking a picture of and posting here. I've been looking around through my junk to see if there's anything I can repurpose as a case / enclosure but finally gave up on that and ordered a nice one that should work great. I could've bought a plastic one at the local electronics shop but I had my heart set on a metal case! 8)

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Oct Tue 27, 2015 2:02 am 
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Gentlemen, what considerations should I have in the placement of the transformers and their proximity with one another? Are there some guidelines or best practices I should be following? Is one inch apart too close? Thanks as always for the advice.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Jun Mon 12, 2017 7:47 pm 
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Location: aston, pa, usa
When I was trying to downsize Colin was good enough to take what was left of the old parts kit parts to supply members who might be trying an old design. Now he is down sizing and returned the parts to me in good order. So if any one needs a 6LE8 tube I've got'em. Just PM me with a snail mail address.

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 Post subject: Re: Building a 6LE8 Transmitter
PostPosted: Jul Sat 08, 2017 6:51 pm 
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Joined: Apr Sat 11, 2015 5:30 pm
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Location: West Point, PA
bill hamre wrote:
When I was trying to downsize Colin was good enough to take what was left of the old parts kit parts to supply members who might be trying an old design. Now he is down sizing and returned the parts to me in good order. So if any one needs a 6LE8 tube I've got'em. Just PM me with a snail mail address.


Bill, you've got this as a kit? I was wondering where to get the coil.


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