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 Post subject: Re: Erla Reflex Radio
PostPosted: Dec Sat 23, 2017 3:15 am 
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Location: Phoenix, AZ
See volume 1 of "Radio Manufacturers of the 1920s" by Alan Douglas, page 190 (Erla chapter). It shows several Erla reflex schematics including one that looks like it might be fairly close to this set.
R/ John


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 Post subject: Re: Erla Reflex Radio
PostPosted: Dec Sat 23, 2017 3:22 am 
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Will do, thanks John.

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 Post subject: Re: Erla Reflex Radio
PostPosted: Dec Sat 30, 2017 8:03 am 
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atwaterkent1, I'd consider that a keeper. Go ahead and learn from and enjoy it. My tastes have been leaning toward the 20's homebrew for some time, and I realize that many are one of a kind with their own story. That's right, there is not another just like it anywhere. Others may have the same parts, but that was someone's personal project and triumph.

Lindsey


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 Post subject: Re: Erla Reflex Radio
PostPosted: Jan Fri 05, 2018 4:21 am 
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I didn't mean to mislead anyone. I hadn't purchased the radio at the time I posted, but was thinking about it and wanted feedback on the ERLA radios. I've purchased the book John recommended,taken Lindsey's advice and purchased the radio. After I check it out I will update everyone.

John, the schematic in the book does look very similar, it's too small to use obviously. I will keep searching for a schematic for it.


Thank you all for your comments.

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 Post subject: Re: Erla Reflex Radio
PostPosted: Jan Fri 05, 2018 5:28 am 
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Location: Phoenix, AZ
Dan,
The Erla chapter in the Douglas book (volume 1) shows that those (admittedly small) schematics were taken from "Radio in the Home", the November 1923 issue. The American Radio History website has that issue online:
http://www.americanradiohistory.com/Arc ... 23-Nov.pdf
Download that PDF and look on page 12 and following, and you'll find an article and full-size schematic that's easy to read. It just takes a bit of digging.
R/ John


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 Post subject: Re: Erla Reflex Radio
PostPosted: Jan Fri 05, 2018 6:02 am 
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Thank you so much for your help John. I've downloaded the issue and will read it this weekend and see how many questions it answers for me. I'll update all in the near future.

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 Post subject: Re: Erla Reflex Radio
PostPosted: Jan Sat 06, 2018 7:15 pm 
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Attachment:
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Picked up radio today and pulled the chassis. Uses 45V B and 5v A for power. Tuning condensers have one plate with tuning independent from the others. Tubes are all 01A and check good.

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 Post subject: Re: Erla Reflex Radio
PostPosted: Jan Sun 07, 2018 1:58 am 
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Hooked up power, antenna and ground to the radio. Getting a hum from the speaker and that's all. Checked the audio transformers and one of them has an open primary. Secondary's check 20K ohms.
Now a newbie question. The radio frequency transformers (2) go into tube type sockets. I pulled them both and checked zero ohms between posts marked P&B and the posts marked G&A. I'm guessing G is ground, A is antenna. P and B posts are what?

The audio transformer with the bad winding is the one under the grid resistor. What are my options for fixing it. With a glass case on the radio I'd like it to look original of course.

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 2:42 am 
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Check the carborundum detector, normally, that type of detector is used with bias, often adjustable bias. See if it still tests as a diode. The radio will not work if the detector is not working. If the carborundum detector is not functional a 1N34 or similar can be used as a temp, but no bias.

See your "3,jpg" lower left the cartridge with the thumb screws says "Carborundum".

Try to find data on the cartridge, these may be "restorable" and adjustable. Typically, a carborundum works with high mechanical pressure. That cartridge may be spring loaded. Like a can of clown peanut brittle...

I have some raw carborundum crystal, it detects by bearing down a couple of ounces with a steel point.

If the audio transformer shells can be taken apart, try a careful disassembly, there may be a broken wire from the terminals to the windings. If the winding has a 1/2 x 1/2" core there are replacement windings available to fit on the core, then get covered by the old case.

As far as the RF transformers they must have continuity plate side and grid side, generally lower than 100 ohms.

Again, if these can be disassembled there will either be a broken wire or corrosion. The windings are relatively coarse so rewinding is possible.

Chas

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Last edited by Chas on Jan Sun 07, 2018 2:53 am, edited 1 time in total.

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 2:49 am 
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Hi Chas,
A what? Remember I'm a newbie. What is it and what does it look like?

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 2:57 am 
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Missed my editing,

Look in the lower left of 3.jpg ,it is the cartridge with the thumb nuts on each end. That is the detector, no tube is used for a detector in this radio...

Therefore, there is no grid leak...

Do you have a schematic for this radio?

Chas

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 2:59 am 
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Will do Chas, thanks.

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:07 am 
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Haven't been able to come up with a readable schematic yet. Here's what's on the carborundum - No.30 , a couple numbers I can't make out followed by a space and the number 44.

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:13 am 
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http://www.americanradiohistory.com/Arc ... 23-Nov.pdf

Use link above and scroll down to page 12 or so.

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:15 am 
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I got it or at least a piece that proves that there is no bias on the carborundum.

Attachment:
3 tube erla.png
3 tube erla.png [ 134.62 KiB | Viewed 1688 times ]


Look for the Diode symbol to the left of the upper right audio transformer...

It IS possible the Carborundum is in trade name only and there is Galena inside.

Look at the page 13 of the quoted article and a picture shows an ERLA fixed detector, that FWIK is a galena...

BTW the success of the radio is very dependent on this detector. Unlike a tube that can be operated marginally, the diode works or it don't...

Not a radio to play when there is a nearby electrical storm, POP goes the diode...

If transformer repairs are needed pay strict attention to the polarity of the windings. IF a plate/B+ or Grid /A connections get swapped there will be a 180 inversion of the signal, that may cause the set to oscillate uncontrollably. If that happens swapping any pair will correct it. However, it will disturb the bus wiring and may create additional problems. The swap or correction should occur within the audio transformer.

Chas

Alan Douglas recovered a glass paneled homebrew reflex from the local dump early in his radio hobby. He had to make a new glass front panel. It was displayed proudly in his radio room for many years...

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:32 am 
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That's not it. Scroll down a little further to last drawing on page. It's more of a drawing than a schematic.
Attachment:
300d.jpg
300d.jpg [ 224.51 KiB | Viewed 1688 times ]

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:33 am 
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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:35 am 
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That's not the schematic for this radio. Scroll down to bottom drawing on page you found that schematic and there is a drawing of it.

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:37 am 
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How do I check the carborundum?

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 Post subject: Re: Erla Reflex Radio-Could Use Some Advice on Repair
PostPosted: Jan Sun 07, 2018 3:42 am 
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The drawing is similar not exact. This radio uses 45v B voltage.

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