Just picked up a 1930s Battery operated Coronado
 

Hello everyone, today I just picked up a 1930s vintage battery operated Coronado Radio of which I don't know the model number and I'm trying to locate the service literature for it.

It is in really decent shape yet, but someone at some point in time wired a power cord up to the antenna hookup and I'm hoping no one actually attemped to plug it in that way otherwise this radio may be a shelf queen, it looks really clean underneath as well and looks like there was no servicing done to the radio (except to the battery cables and the addition of the power cord onto the antenna hookups.)

what kind of batteries were used to power this radio and does anyone have any idea which model this might be?

pictures below.

I used to have one. It wasn't a stellar performer and the cabinet was beat up so I got rid of it. I think it took 90V for the B+ supply and 1.5V for the A supply...the A supply voltage is easy to confirm by googling for the data sheet for 2-3 of the tubes and using the lowest filament voltage. (The audio outputs of battery radios often used a tube of double the A battery voltage with a center tap...the ends of the center taped filament would be jumppered together to halve the opperating voltage and double the current)

I got it mostly as a curiosity piece as I've never owned a battery powered tube radio set before, and thought it would be an interesting piece to try and fix up.

That power cord hookup to the radio's antenna terminals almost certainly would destroy the radio (not to mention possibly starting a fire) in the blink of an eye, if the plug were to be inserted into an AC outlet. Why on earth would anyone do anything like that?

It's a model 650A-B-C in Riders vol 8.
Those are 2 volt filament tubes using 90 volts B+. Chances are, the antenna coil might not be damaged, if 120 ac was applied. :scratch2:
It's easy to build a power supply because it uses only a A+ & B+ source.
Doesn't use a grid bias supply.

Yeah, I checked the antenna coil and it still had continuity so I think it's fine yet. It does have AVC which is good.

Despite Jeff's dour predictions , capacitor C1 would save the antenna coil if AC was improperly applied to the antenna terminals .

Indeed you are correct, when I tested C1 between the antenna terminal strip, and the antenna coil, C1 measured open.

I did some research and I figured out that this radio is a Coronado Model 650B which was a rebadged Arvin "Phantom" Series Farm Radio Model 628B.

I thought that was kind of interesting.

I like the cabinet!

Go to your local dollar store and get 10 9V tranaisistor radio batteries to use in series for B+, and some D cells for the filaments. The 9V batteries can be clipped together in series using their own terminals, and then the first and last ones can have wire leads with alligator clips soldered to them, which you can connect to the radio's power connector. For the A battery I'd use 2 D cells in parallel.

Before you apply power you may want to do a basic replacement of capacitors, especially any electrolytic capacitors, the AVC filter, and the audio grid coupling capacitors.

The reason these radios sound worse than normal radios, is the audio output stage is necessarily very low powered, so the speaker is designed for efficiency rather than sound quality. They can be okay though. I like yours because of the fancy grill design and late 30s deco cabinet.

The radio might not work because the filament voltage should be 2 or 2.2 volts. Those tubes are probably a little tired and need the proper voltage.
I have a Coronado model 550 tombstone made by the same company, but using a single 33 tube in the audio output. It originally had a magnetic speaker that sounded lousy. I installed a PM speaker and output transformer.
Not much audio output, but doesn't sound bad. :thmbsp:

How do you parallel "D" batteries? is it positive to positive or negative to negative?

Both at once...

OK, so I take it that a battery clip like the one in the link below won't work in my case?

https://www.radioshack.com/products/...battery-holder

I didn't realize there was a capacitor in the antenna circuit to protect the coil in case the latter were inadvertently connected to 110v AC power. This will teach me not to say anything like what I said in my post without being sure of the facts.

It's easy enough, unless you have the schematic in front of you!
A lot of sets don't have that capacitor, so it could've been detrimental.
They probably included it because of lightning strike is more common in rural areas.

Are you sure the two batteries should be connected in parallel? Because I'm only getting 1.5 volts connecting them that way...:scratch2:

I've also tried connecting 2 sets of D batteries in parallel and I'm only getting 1.4 volts, so not even close to the correct amount of volts needed to power the radio's filiments...

Well I was able to rig up a temporary battery rig for my radio and it works...Sort of.

I hooked up my signal generator up to the radio and it picks up the 456 kHz IF Signal fine (all though it picks it up all across the whole dial and not just around the 550 area of the dial), and I tweaked the IF cans and surprisingly enough they are peaked where they are supposed to be, I tried adjusting the Oscillator and Antenna adjustments on the tuning capacitor and they didn't seem to make any difference and the 600 kHz oscillator adjustment is under the chassis so I couldn't adjust that.

But I can't get it to pick up any radio stations I can't even get it to pick anything up from my signal generator tuned to various stations on the AM Band, hooked through the antenna, and the antenna coil tested fine when I tested it.

Any ideas as to what may be going on?

Note I didn't advise you to put the batteries in parallel....I only advised you HOW to connect them in parallel.
The trouble with using standard alkaline D cells to supply the 2.2V filaments is that new alkaline cells are 1.5V so parallel will not give you enough voltage and series will give you too much (unless you use used batteries that are down to ~1V ). The only advantage of parallel connection is that the batteries will last longer.
One thing you could do for the filaments is connect the batteries in series and build a LM317 circuit to regulate 3V down to 2V...A filament rheostat is another solution.

Got an oscilloscope to check if the converter or oscillator tube is oscillating? And do you have a decent length of antenna wire 15-40' hooked up? If you have an antenna and the IF works then either the local osc is dead or the RF path between the antenna and the Mixer/Converter is bad....If you passed IF down the antenna and it didn't seem attenuated in comparison to injecting it at the 1st IF then that favors the Osc being dead.

No but someone else on here said to connect 2 D cells in parallel to get the voltage I needed for my filaments, you just happened to reply when I asked about how to connect batteries in parallel.
Anyways Rechargeable NiMH batteries are 1.2 Volts which if I connected 2 of those together I would get 2.4V which would be the correct voltage I need for the tube filaments, and they make NiMH Rechargeable D cells that are as high as 12,000 mAh, which would be more than enough juice to power the filaments.

I'm guessing the oscillator isn't running because the tubes aren't getting enough filament juice.

Those tubes aren't that easy to source. They only used them for few years.
The 1C6 can be replaced with a 1A6.
I checked over my 2 volt battery set. At the time, I built the power supply using a transformer from a scrap VTVM. I didn't have a regulator chip at the time, so I just used discrete components.

Battery radios are the most underated old radios around. When I first started collecting I too didn't give them a second look with all those ragged wires and clips hanging out of the back. The truth is they're unique looking sets and perform very well once restored. You also don't get AC line interference, so the audio is clean. The only drawback with the wooden models is that there's usually no dial lamp, or, at best, a dim one.
Unfortunately, very often, either a surge or an attempt at hooking an AC line to them was not uncommon. Usually what happens is an instant blow-out of all the tubes. In my experience of dealing with portable battery radios, it's a 50/50 chance that the tubes are good. I've replaced the tubes on these many times.

I agree this is a very nice looking set and is also supposed to be based on one of the best designed sets Arvin made at the time, the Phantom Series.

And I think once I recap this set, and get some proper Rechargeable D cells and a good battery clip for this set I think I should be able to get this thing going. :thmbsp:

I'm curious, if I were to use some 1.2V NiMH rechargeable D batteries to power the filaments in this radio (2 1.2V batteries in series would give me 2.4V roughly) what kind of diode or what size of dropping resistor would I need to drop the extra .3V to get the voltage down to the 2.1V I need for the tube filaments?

Or would it not matter in this case?

Thanks for your help.

Any silicon diode such as the 1N400 series will drop around .6V which in my book will be close enough. I'd go so far as to suggest that two Alkaline batteries in series with the same diode will be close enough too. If you're worried about a few tenths of a volt, then put two diodes in series and when the batteries run down you can short across one and get any remaining life out.

I've got several 1N4007 diodes would those work?
Would I tie the diode across the negative or positive lead of the battery clip?

Ive done a few of these 90V but the filament was 1.5v. Anyway I use 60 AA batteries for 90V power. I have soldered in connections for 45V too for other radios. I doubt the AA's cost much more than the 9V ones but you have to solder holders together and yes more time involved. About every 3 years +/- 1 they need replacing if they are a good brand.

I like the sound of the battery radios. They dont have much static type sounds as they arent hooked to your homes power supply. If your fortunate enough to have a long wire antenna that will increase the sound too. My outdoor antenna is about 90 feet long.

Reminds me of what I did in the mid-50's. I would dig through the trash bin behind the TV shop for battery packs for a Zenith TO or similar. The "A" side was usually dead, but the "B" side was good for about 75 or so volts.
That side was usually sealed in tar and lasted quite a while. :thmbsp:

American ingenuity! :thmbsp:

I did forget to add that the smaller voltage battery will often just last hours as they have draw. The 90 volt pack will last for the life of the batteries. I did buy a cheap brand of AA's and I got what I paid for, they lasted about a year.

On a side note and slightly OOT, it always amazed me that anyone would buy a battery only tube radio. "B" batteries were never cheap!
I'm referring to the time when most homes had electricity. Portable, battery only radios were made until about 1956.
Three way portables were only about $5 to $8 dollars more and you can use them all year.:scratch2:

In my case, it was for safety... as a kid, I was always taking my radio into the bathroom, a battery only set with no cord was much safer. “B” batteries were great xmas and birthday gifts :thmbsp:

jr

My step mom has a Coronado set that has three way power. it had a compartment and a plug for a 90V/1.5v A/B battery (i think). I think it was late 40s or early 50s. I'll find more info next time I visit.

I also have an Emerson 508 (battery only) and a Motorola 5A7A (three way) that use a 67 volt B and a D size A.

EDIT: nabbed photos off epay. empty box lol.

two 45 volt "B"s and two 4.5 volt "A"s. hmmmm.......

The radio was made by Warwick. I wonder what battery life was like? Using a 9 volts "A" source makes the switching circuitry simpler between line and battery.
My luggable Emerson 523 uses the same battery compliment.

The 1st one I fixed was my Dad's farm set before they had electric. Its a 1949 I think. Airline model. My Dad told me even back then the batteries were expensive. They used it until quite a while after they got electric then gave it to an Uncle who had electric but no radio and he used it until around 1960 I think.

It needed and needs a decent antenna run to pick up much, maybe 10 foot minimum so isnt much of a portable. It only has a screw to attach an antenna wire to it. A built in antenna would have been better. My Dad ran an antenna around the outside of the house and stapled it on so they could listen to the Grand Ole Opry on the weekends, plus local stations during the week.

All that said, I agree, anyone with electric was better off with a plug in electric option.

I have a post-war Zenith four tube farm set.
I got lucky and picked up two battery eliminators intended for farm sets at a swap meet a while back. I have one in the Zenith.

OK so I had ordered some capacitors for this radio over at AES (Antique Electronic Supply) and I had put the order in on Friday (November 27) and I had gotten the order confirmation email from them on Sunday (November 29) and I checked the tracking on my package and it says that a shipping label was made for my order on November 29 (Sunday) and that the postal service was waiting to receive the package, and that's the last update on my parts order from AES.

Here it is December 2, and its still not left AES's headquarters, (according to the tracking number as of today) and I paid the extra money for priority mail.

Does anyone know what's going on?

Dunno. AES is usually pretty quick, but they're in Arizona and I'm in New Mexico. It's probably holiday related delays.

I messaged them and they said it was because of all of the online black friday sales that more or less overwhelmed the postal service there, which is understandable because I did hear about that on the news on the radio.

A little update, I got my 2 D-Cell Battery Clip today that I ordered from Radio Shack last Week, and I wired it up just like you guys suggested with a couple of 1N4007 Diodes wired in series with the Positive wire for the Battery clip and that then in turn was wired to the radio's "A" Battery hookups.

I was able to get the radio to work for a little bit (with my signal generator hooked up for a signal source) and I was able to get the test tone to go through the Antenna hookups properly (it was actually coming in where it was supposed to on the dial and not all across the dial like it did before).

Then going through the grid cap of the 1C6 tube I was also able to get the signal through there as well (but it was coming in all across the dial and not at just one spot like it was supposed to).

But then when I went to try and adjust the IF Cans to make sure they were peaked correctly the signal would cut in and out and then it finally completely cut out to the point that I can't get anything out of the radio audio wise anymore, and I did check the batteries to make sure there was enough juice and there was plenty of juice in the batteries, and they were putting out 2.3 Volts.

I'm still waiting on my capacitors (checked the tracking and they are supposedly arriving on Friday (which is kind of rediculous because I shouldn't of had to wait almost 3 weeks for my parts to come like this).

Anyone have any ideas as to what may have happened to my radio?

Thanks.

Would any of the batteries listed in the link below work for the "A" battery on this radio?

https://www.batteriesplus.com/batter...ed-lead-acid/2

I didn't know 2 volt lead-acid rechargable batteries were still available.
Now, you'll have to build a charger!