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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Wed 22, 2020 4:28 pm 
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I think Chas means like this:
Attachment:
Untitled6.jpeg
Untitled6.jpeg [ 7.45 KiB | Viewed 560 times ]


I was asking, describe exactly how the phones are connected when running as a 1 tube set.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Wed 22, 2020 6:04 pm 
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Dan,

Nix the ground connection as mentioned above. Use the radios ground connection for the AF probe. The wrong ground/return could cause a short loop via the grounded power outlet and any ground that may be at the ARBE. To doubly sure, remove any ground from the ABC at the ARBE that connects to the radio.

Remove the radios ground connection to EARTH in event of a loop from the RF/AF oscillator. This has to be done because the generator is line powered.

Use the 50K pot as shown below, The pot will allow reduction in the available Audio voltage, the cap will isolate the pot and the audio instrument from AB or C dc voltages in the radio so the radio can still operate.

Attachment:
Isolated AF injection probe with attenuator.png
Isolated AF injection probe with attenuator.png [ 86.47 KiB | Viewed 556 times ]


Experiment with the scope to see the action of the pot and the AF wave form by using the probe. Experiment with +- trigger, trigger voltage, vertical input attenuator, horizontal sweep, pattern positioning so that a sine wave of three cycles is displayed... in the upper screen area, input to channel B and do the same position the trace in the lower portion of the screen.

As for the 47k resistor, set aside for now...

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Wed 22, 2020 6:11 pm 
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jrehkopf wrote:
I think Chas means like this:
Attachment:
Untitled6.jpeg


I was asking, describe exactly how the phones are connected when running as a 1 tube set.


Exactly as you suggested. Disconnected the lead to post #2 on the H transformer then connected the headphones to the disconnected lead and the lead to post #1 on the same transformer using gator clips. Antenna wire connected directly to the input wire instead of the post on the back.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 23, 2020 6:00 pm 
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atwaterkent1 wrote:
I had the C voltage on. I just tested it again with the 90v connected and the C voltage off and it works great as a one tube. When I turn on the C voltage the signal cuts out. With the C voltage on and the 90v disconnected, it works again. :?

A mystery. Can you take careful voltage measurements at the tube pins when working and then not working? To see what is changing?

Addendum: I would put the battery wiring back to original locations to match the schematic. Maybe discover a mis-wiring when doing this.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sat 25, 2020 1:19 am 
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Got tied up working on the Association budget for a while. Made the probe rig tonight.

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Don't have a knob for the pot, not too many 20's rheostats had that kind of shaft.


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Not sure what the circles around the wires mean....

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CCI04242020.jpg [ 400.5 KiB | Viewed 524 times ]

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sat 25, 2020 1:53 am 
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jrehkopf wrote:
atwaterkent1 wrote:
I had the C voltage on. I just tested it again with the 90v connected and the C voltage off and it works great as a one tube. When I turn on the C voltage the signal cuts out. With the C voltage on and the 90v disconnected, it works again. :?

A mystery. Can you take careful voltage measurements at the tube pins when working and then not working? To see what is changing?

Addendum: I would put the battery wiring back to original locations to match the schematic. Maybe discover a mis-wiring when doing this.



I haven't changed the power connections yet.
Power cuts off at plate and grid pins on all tubes when C power is turned on.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sat 25, 2020 2:44 am 
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atwaterkent1 wrote:
Not sure what the circles around the wires mean....
Shield, if coax used. Ignore if twisted pair...

That symbol is 30yo, maybe there is a new symbol, its like jargon. Change the word, keep the meaning, confuse the next generation :roll:

Knob is a convenience. Once a level is set for testing keep the same setting when 'scoping will reveal the loss or gain in the amp test points. Looks good.

So there is something weird with the "C" source?

I been busy too. Had to buy shelving for all the extra groceries. Set it up, wife nixed it. The open grid like shelves are a danger a cat may drop its paws through. They eventually get into everything...I had to tear it down, back to Homer and get some carpet runner for a liner. Shelving will go up tomorrow or Sunday. I have top cut the liner (neatly) for every shelf. After I find a 3' long straight edge :roll:

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sat 25, 2020 5:53 pm 
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"After I find a 3' long straight edge"

You have doors in the house? 6 ft long straight edge...

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sun 26, 2020 12:33 am 
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Got it !!!! Working good!!! I can't honestly say what I did to get it working. I was re-checking some connections, tightening screws and cleaning some up. The last thing I did was find a solder joint that was somewhat loose. I re-heated it, added a bit more solder and then turned on the power (not expecting it to make any difference) and out of the speaker, very loudly, was WWJ 950. It actually startled me for a second, as I said, I wasn't expecting what I did to really make a difference.
The connection I re-soldered ran from the volume control to the #2 post on the K transformer and back to the A- (after branching off to the #3 post of the L transformer.
I want to thank Chas and Jeff for all their help and hanging in with me through a long process and getting this radio working. Having a working Radiola Grande in my collection feels great and I couldn't not have done it without their help. Thanks Chas! Thanks Jeff!

Attachment:
RG 1.jpg
RG 1.jpg [ 577.48 KiB | Viewed 508 times ]

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sun 26, 2020 12:40 am 
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I've never been able to pull in a small oldies station in Walled Lake with any of my radios, until now!! A great bonus to now have oldies coming in over the air. :D I have to run the ARBE at 1.5V to get 1.3 at the pins. I'm also getting several broadcasts with the antenna hooked up to the "Longwave" antenna.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sun 26, 2020 2:06 am 
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atwaterkent1 wrote:
I've never been able to pull in a small oldies station in Walled Lake with any of my radios, until now!! A great bonus to now have oldies coming in over the air. :D I have to run the ARBE at 1.5V to get 1.3 at the pins. I'm also getting several broadcasts with the antenna hooked up to the "Longwave" antenna.
Congrats! Dan

Please finish up making your signal injector probe with the 'scope experiments.

I have looked through those 'scope books I have and will pick one useful to you. All of them have information how to use the scope for TV work but that is not needed :(

I have some paperbacks of the "Oscllographer" (very hard to find) I would only scan those, there are some good scope tricks...

And thank you for getting back to both of use.

Your hard work confirms one of my primary mantras on 20's radios clean and check all the connections, then check again :D

I am surprised at the sensitivity, I would think no more or less than any other regenerative radio...

In the note above, a joint is indicated, would this be a "flying" joint in the bus wire?

Best!

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sun 26, 2020 2:21 am 
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jrehkopf wrote:
"After I find a 3' long straight edge"
You have doors in the house? 6 ft long straight edge...
:lol: :lol:
After rummaging in the shed, I found some 4' shelf standards. Worked perfect and didn't have to take a door off the hinges... Shelves are up and the tops covered so the cats won't get hurt.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Sun 26, 2020 3:01 am 
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Chas wrote:
atwaterkent1 wrote:
I've never been able to pull in a small oldies station in Walled Lake with any of my radios, until now!! A great bonus to now have oldies coming in over the air. :D I have to run the ARBE at 1.5V to get 1.3 at the pins. I'm also getting several broadcasts with the antenna hooked up to the "Longwave" antenna.
Congrats! Dan

Please finish up making your signal injector probe with the 'scope experiments.

I have looked through those 'scope books I have and will pick one useful to you. All of them have information how to use the scope for TV work but that is not needed :(

I have some paperbacks of the "Oscllographer" (very hard to find) I would only scan those, there are some good scope tricks...

And thank you for getting back to both of use.

Your hard work confirms one of my primary mantras on 20's radios clean and check all the connections, then check again :D

I am surprised at the sensitivity, I would think no more or less than any other regenerative radio...

In the note above, a joint is indicated, would this be a "flying" joint in the bus wire?

Best!

Chas



It was actually a screwed down connection, the solid wire had a connection ring soldered onto it and the solder had a crack in it, still somewhat connected but wobbly.

Signal injector probe is finished, one of the guys here is sending me a knob just to make it a little easier to adjust the pot. We still have the AK6 to get running and I'm wondering if we could use the new probe to help repair it?

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 Post subject: Re: Radiola Grande Restoration - Working!!
PostPosted: Apr Sun 26, 2020 3:26 am 
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With the radio running it was time to remove the jury rigged caps and re-stuff the condenser housing. I removed the two large square condensers and then removed the connection posts from them. Next I cut a piece of heavy gauge cardboard with two slots to clear the wiring attached to the terminals and long enough to fold completely around the inside of the box. The terminals are held between the original insulator board and the heavy gauge cardboard, with the cardboard folded all the way around the inside of the box, it puts pressure in the other end of the cardboard and holds the terminals in place. The pressure increases when the side is put back on the box, pressing on the cardboard. The leads and the connection points of the caps and wires are coated in silicone for insulation. Finally, the condenser is back in place.

Jury rigged set-up....

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Condenser opened up......

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New caps......

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Cardboard folded over...

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Side of box reattached.....

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Re-installed condenser.....

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Powered up and tested, radio worked fine.

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 Post subject: Re: Radiola Grande Restoration - Working!!
PostPosted: Apr Sun 26, 2020 1:30 pm 
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Great job, Dan - congrats


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 Post subject: Re: Radiola Grande Restoration - Working!!
PostPosted: Apr Sun 26, 2020 2:12 pm 
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Quote:
We still have the AK6 to get running and I'm wondering if we could use the new probe to help repair it?
Yes, it is another useful tool...

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 Post subject: Re: Radiola Grande Restoration - Working!!
PostPosted: Apr Sun 26, 2020 3:40 pm 
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Great news!!! I knew you were close.

Do you realize that you put in 94 mf instead of 1 mf? May not matter at that location.

Which connection, blue, green, or red?
Attachment:
2020-04-26_10-15-17.jpg
2020-04-26_10-15-17.jpg [ 110.98 KiB | Viewed 480 times ]

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 Post subject: Re: Radiola Grande Restoration - Working!!
PostPosted: Apr Sun 26, 2020 5:15 pm 
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Yes, I know about the condensers. The connection is the one between the red and blue circles that runs back to the bakelite mounting board, a screw down terminal.

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 Post subject: Re: Radiola Grande Restoration - Working!!
PostPosted: Apr Sun 26, 2020 7:04 pm 
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jrehkopf wrote:
Great news!!! I knew you were close.
Do you realize that you put in 94 mf instead of 1 mf? May not matter at that location.
Which connection, blue, green, or red?
Attachment:
2020-04-26_10-15-17.jpg
Ya, and electrolytics at that... Play this radio 10-15 years from now and the ARBE-III will be grunting dumping current into those leakers...

1-2 mf at best for "B" bypasses. Although "I" would use foil/poly something or other, a metallized is fine if a 1 mf is too fat a couple of .5's will be fine. Paralleling also helps the dv/dt, though I would not expect any fast rising pulses in this radio...

BTW, most "modern" digital service instrument won't give a value of an extremely leaky paper condenser. however, old service capacitor bridges will give at least a slight "wink" on a leaker. I found the two Heathkits will especially if the sensitivity is changds to electrolytic. Most of those paper cap packages are either .5mf or 1 mf. Cap banks will parallel them to get a higher mf... If one really has the need to know, put the cap package in a toaster oven at 180F for 1/2 hour. This usually dries out enough moisture and raises the resistance enough for the bridge to get a reading. Put foil under the cap to catch any wax.

Next: How to bus wire a radio :roll: (There is a PDF for that)

I am very pleased that Heyboar got the weird audio transformers exactly replicated, they are #1... :D

YMMV

Chas

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 Post subject: Re: Radiola Grande Restoration - Working!!
PostPosted: Apr Mon 27, 2020 2:29 am 
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If I'm still around in fifteen years I will be happy to replace them!

Cleaned up the cabinet and took some photos of the old girl.....

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Note how well the added battery box with two AA batteries for the C power fits into the original C battery holder.

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