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 Post subject: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Sun 13, 2021 2:11 am 
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Joined: Mar Sun 07, 2021 7:57 pm
Posts: 24
Location: Phoenix, AZ
I picked up a Crosley 3R3 Regular and started going through it. The three tubes test good (80+)on my Knight emissions tester. There appears to be only three components to test the two wafer capacitors and the megaohm grid leak resistor. The grid leak resistor is labeled 1Mohm measures 1.1 Mohm. The wafer capacitor it bridges measures 273pF the schematic indicates 250pF. The second wafer (not bridged by a resistor) measures 356pF the schematic calls for 2000pF, so that one is off. The primary and secondary transformers do show a resistance value and its pretty consistent between the two transformers around 6.8K/697ohms for both, so no winding swap needed. I'm waiting for a Sonochord speaker from EBay/EPray as I picked up three 1920 era sets that will all need a speaker or headphones. I did ultrasound the tuning capacitors and tried to eliminated any fin drag. I have been gently wire brushing any connection I have removed including the tube contacts, sprayed a very small shot of deoxit on the switches and turned them many many times, that's about it.

Here are my initial questions, any help will be appreciated.

1) Should the out of spec wafer cap be replaced, if so what are available and acceptable substitutions?

2) To test it I will have to get a ARBE III eventually but for now I will use 9-volt batteries in series to hit close to 90V on B+, I ordered a four slot D battery holder for the A voltage, I see C terminals but not sure what to do there and what to use at C? I have seen A+ jumped to C- and no C used in a thread, what's best on that C voltage?

3) I do not have an antenna and have read the forum for this set where they recommend a 50-75 foot antenna grounded. I really have no idea how to set this up as I am new to vintage radio. I assume there is a good thread or recommended You Tube on how to make a low cost antenna for these radios. I live in Phoenix so there should be many close AM stations. Can I get a link to a step by step way to make and properly ground an antenna. I have an extra 5-foot copper ground rod as I needed to ground a small solar set up, if that is usable.


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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Sun 13, 2021 2:43 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 16738
Location: S. Dartmouth MA 02748-1225 USA
Quote:
1) Should the out of spec wafer cap be replaced, if so what are available and acceptable substitutions?

2) To test it I will have to get a ARBE III eventually but for now I will use 9-volt batteries in series to hit close to 90V on B+, I ordered a four slot D battery holder for the A voltage, I see C terminals but not sure what to do there and what to use at C? I have seen A+ jumped to C- and no C used in a thread, what's best on that C voltage?

3) I do not have an antenna and have read the forum for this set where they recommend a 50-75 foot antenna grounded. I really have no idea how to set this up as I am new to vintage radio. I assume there is a good thread or recommended You Tube on how to make a low cost antenna for these radios. I live in Phoenix so there should be many close AM stations. Can I get a link to a step by step way to make and properly ground an antenna. I have an extra 5-foot copper ground rod as I needed to ground a small solar set up, if that is usable.


1 - The cap in question is fine as long as it does not show any leakage. It is a bypass cap so the value is not critical.

2 - Using 9-volt transistor radio batteries my be problematic as they will have a relatively high impedance and may cause feedback. Use alkaline 9-volt batteries and bypass the 90 volt pack with a 1mf/630v capacitor if uncontrollable oscillations occur.

"D" cells will not last but 2-3 hours, the tubes will draw 3/4 of an amp. A better choice is a 6 volt L/A gel battery of at least 10amp hours.

The attached schematic does not show the use of a "C" battery.

This schematic does have the "C" battery. Use a 4-1/2 volt "C" battery. Can be made from a 3-cell holder for any size battery. A scrap LED palm flashlight will have a 3-cell holder for AAA or AA cells, these would be fine. A "C" battery will reduce the "B" current.

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This is what a "typical" 1920's antenna was like...

http://www.atwaterkentradio.com/AKInstr ... okVol2.pdf

The ground rod you have is good for this purpose. I suspect dry soil so bonding existing grounds with #6 bare flexible cable may be beneficial.

The Crosley radio is a regenerative reflex, so it must regenerate to get signal strength but not so much that it squeals. That is the purpose of the control that pulls out and pushes in the regeneration coil. GL... Chas

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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Sun 13, 2021 2:01 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1077
Location: Bristol TN 37620
Chas is giving great advice (as usual) especially with actual
battery use. Another Chas credo, check your soldered
connections carefully and make sure you're getting
continuity. Many might look good but not make a good
connection.

If you choose not to use C voltage, jumper C- to A-, not A+
That connection is wrong. Being you're using batteries,
C volts will prevent battery drain and better tone.


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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Sun 13, 2021 4:01 pm 
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Joined: Mar Sun 07, 2021 7:57 pm
Posts: 24
Location: Phoenix, AZ
Thanks for the advice. It will be a thrill to get some sound out of a 100 yo radio. I had planned to use batteries to test the radio but can see its not a good long term solution, so I will order an ARBE 3. Regarding inspecting and testing the solder joints if they look sound (they are large joints on metal rods) I assume leave them alone. I'm sure they are all lead solder so reflowing them proactively does not seem like a good idea. Is simply checking for continuity on each side of every joint a reasonable way to test them?


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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Sun 13, 2021 4:10 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1077
Location: Bristol TN 37620
Yes, as long as you're getting continuity between points,
like A+ and the A+ tube socket. (example). The solder
connections deteriorate over time.

The Arbe is a great choice and will serve you well. Having
good audios is real plus.


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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Sun 13, 2021 5:21 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Hmm, where your not all that familier with re-soldering, yes, I would not be proactive in this instance and not of every joint.

Folks will choose a too small a soldering iron, fail to use active fluxes or choose the wrong solder.

The wiring in the Crosley is #12 round "tinned" bus, "special" tools are used to handle it, for example 6" full-round nosed pliers and flush cutting diagonal pliers.

I would "guess" that when many of the same radios were made, a jig form is used outside of the radio and the wiring made up as "parts" and soldered in later in production.

What happens is soldering is a metallic eutectic process, at the juncture of the solder and the base metal copper the metals mix. but after many years the marriage becomes stale, what happens is inter-granular corrosion. A measurement with an ohmmeter will be O.K. but at radio frequencies a poor semiconductor occurs.

"I" would re-solder any joint that has actually broken (have too right?), slightly loosen and re-tighten all electro-mechanical joints, that process breaks dissimilar bonds that have had 95 years to develop, then re-tighten that connection.

Be careful with Crosley insulated parts. Crosley designed with a price point, essentially as low as possible. If he could have made things like tube sockets out of road apples he would have...

The tube sockets, rheostat bodies, insulated bits of tuning condensers, especially the sides of the Crosley book condenser and the knobs. They are made of a material called "mud", it is a mix of coal dust, barytes, lampblack and shellac, it is thermoforming, i.e. it will slowly deform at the temperature of an attic at 140F. If a terminal that has a soldered connection to a mud part is re-soldered the part will deform and fail. Such connections have to be disassembled and the lug soldered away from the part, when cool re-assembled.

Mud parts are soluble in alcohol, toluene, acetone, those solvents will melt the top finish and reveal the sparkly coal :x

Cleaning mud parts with 409, window cleaner with ammonia or any other "super" kitchen/bathroom cleaner will strip off the top layer of the mud part too...

The weakest mix of Murphy's Oil Soap, is O.K. used with dampened cloth. Mineral spirits used with dampened cloth. Do not get aggressive with the dials or the intaglio fillings will come out. The intaglio is repairable but a bit time consuming.

This model Crosley uses a long terminal bar for construction of the circuits, this material is "Condensite" a fiber, hard rubber compound it is less temperature sensitive but it is brittle like the "mud" parts... Use care.

The tube sockets of "mud" will sometimes deform and/or the key slot will chip out. Replacement is the only cure as epoxies will not bind well to mud. I have use super glue to bond a broken Crosley book condenser and it seems to hold up, but the key slot in a tube socket is under strain...

Tubes can have the same solder joint problems at the ends of the pins. The pin will have to be re-soldered if the tube fails to light and the filament is not open or the tube makes strange noises because of bad connections to the grid and/or the plate. The Crosley tube sockets make contact with the tip of the tube pin, the tube testers contact the sides of the pins, be sure the tip is cleaned of the grey oxide and the sides of the pins are clean for good contact in the tube tester. If re-soldering the tube pins, be sure that the pin does not get overheated, Bakelite is tough but it will blister and the pin get loosened.

Oh, the "boing, boing", noise when an operating tube is lightly tapped with the finger is normal...

"S" bulb tubes, if dropped and don't break can have bent elements and short, there is a gloved hand tapping technique that can bend the elements back into position and clear the short.

Your posts indicate you are genuine thrilled with this old radio, as I was when I first discovered them 60 years ago. Yes, I made my handling mistakes and learned, I replaced the parts I damaged. Hopefully these prolific "cautions" I have mentioned help prevent an "accident".... chas

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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Sun 13, 2021 5:50 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1077
Location: Bristol TN 37620
Chas, an excellent review, and wise advice (as usual)


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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Mon 14, 2021 11:36 pm 
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Joined: Mar Sun 07, 2021 7:57 pm
Posts: 24
Location: Phoenix, AZ
Chas, I appreciate the construction history it makes the radio com to life. I will read the restoration notes you provide and will follow them. I will spend the next weekend testing the solder joints for continuity and resetting the mechanical connections. I should have a possibly functioning speaker, antenna, and ARBE 3 in two weeks and we will see what noises comes out of this thing.

From you post regarding a similar short wave regenerative radio (and likely all vintage radios) you stated do not use the home AC ground. So what are people using? So what does work for a noiseless ground? Connect to a pipe if close enough, or driving a ground rod and running the ground wire somehow to where the radio will sit? Is there an easier to manage option?

Thx


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 Post subject: Re: Crosley 3r3 Regular Restoration Questions
PostPosted: Jun Tue 15, 2021 12:33 am 
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Location: S. Dartmouth MA 02748-1225 USA
Quote:
Connect to a pipe if close enough, or driving a ground rod and running the ground wire somehow to where the radio will sit? Is there an easier to manage option?
All that you mentioned are the answer.

The RF induced currents flow from the antenna (and back from the ground. Since it is desired that radio be received and not noises keeping the ground (I prefer Earth) wire as short as possible is ideal.

Such a "long" wire antenna is considered to be aperiodic, not resonant, to any particular frequency. Because of this and the fact that the inverted "L" (Marconi) antenna has a high impedance at the point where it attaches to the radios input circuit that impedance will vary with the frequency tuned. In some radios that input is tuned separately.

There is a method to "eliminate" the ground. That is to replicate the antenna in approximate length with a fully insulated wire that travels under the antenna for best results or totally away from the antenna as close to but not connected to the Earth. The wire is called the "Counterpoise". As imagined, just as "messy" as an Earth ground if not more so.

https://en.wikipedia.org/wiki/Counterpo ... und_system)

The best online example of the typical "antique" radio antenna are from magazines of the 20's Modern descriptions for the receiving antenna invariably fall back onto resonate transmitting antennas.

The other method is to use a tuned loop antenna, it can be an "antique" original, modern antique replica or a modern loop. Some of the commercial loops are very pricey and include an extra coupling winding. In this Crosley that coupling winding would not be used. The loop will have to be tuned separately as once the radio moves off the current station by 20khz (two stations) the signal will become weak. The loop must include its own, dedicated tuning condenser, that allows the loop to resonate (tune) the entire BC band

Least I forget this Crosley may not tune any higher in frequency than 1350khz or so.

My preference to connect a loop the wires from the Ground and Antenna are "tinsel" cord. A single very flexible fabric covered wire, no more than 4' long. The tinsel cords are "floppy, soggy", in that they will lay flat like string yet conduct the RF currents. I will salvage them from a tinsel speaker extension cord by pulling through one of the cords and creating two single cords.

For a loop to work successfully, the home must be of wood construction or a table at or near a window that permits the radio signals to enter. The loop can be a solution...

However, loops are "generally", not favored for use with a regenerate set, like the Crosley. The set has its own RF field depending how far into regeneration it is operating. This field can be captured by the loop and setup oscillations that are problematic. Meaning, people walking in the room, changes in regeneration dependent on how the loop is turned.. Keeping down the regeneration and keeping the loop at least the 4' away helps.

In regard to a post of mine in answer to a shortwave set. I see design issues. As more information about the homemade radio come to light the problems will become more clearly defined.

Home made short wave sets have to be very carefully designed not only the circuit but the layout is critical. May well be a great set on paper, but assemble wrong without regard for signal paths and incidental coupling, (like the loop example above) it can be a steep learning curve.

With a commercially made radio, it once worked, unless in poor condition electrically or highly modified, the set will work again.

The early 20's era sets were an engineering marvel, it took "some" expertise" to get good performance. They are far and away from the AA5, radio of the 30's to 60's turn on and tune the station does not apply here... Folks that could, quickly abandoned their battery sets, the battery nuisance and expense, a radio that only little Johnny could make work. The pain of the battery radio high price in the 20's did not go away. So many went to the attic, saved for some other day, a day when they could be truly appreciated as the engineering marvels that they were.

Much easier to own than a Model "A" Ford and you don't need a road to travel the air waves.... chas

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