[captainclock1988]

Hello everyone today I picked up locally a 1930s Coronado (Gamble-Skogmo) AM/Police farm radio that is almost mint in condition and still has all of its original Coronado branded tubes in it yet, and on top of that is electrically unmolested (except for the battery cables and the antenna wires which were jury-rigged), it also still has its original GOAT shield on the 1A4 tube in the radio (the only tube in the radio that was shielded).

This radio I think should be easy to get going again, the problem is I don't know the model number on it because the model number tag seems to be missing (but still has the original tube placement chart on the back of the radio chassis). 

I know someone on here mentioned a website where you could type in the tube lineup and search for a radio model (and service info) that way.

I have some pictures posted below for your information so that maybe someone on here might recognize it by the pictures.

I'm thinking it might be a rebadged Zenith possibly because there were some Zenith capacitors in the radio that look to be factory original, but not sure, and if it was a rebadged Zenith I'm not sure which model Zenith it would be.

Also this is my first farm radio I've ever worked on so I'm not sure what I would do battery wise to power this radio.

Thanks for your help!

-Levi

[Eliot Ness]

The website you're looking for is the grillecloth.com site:

https://www.grillecloth.com/

On the left you can select the Radio Finder database or the Zenith Finder database

You might want to downsize and crop those pictures a bit, they're awfully large.

[captainclock1988]

Hi Elliot, I just looked over at that site and it won't let me put in Coronado into the company name spot because it only allows 5 letters in the spot, and this is a 6 tube radio and it only has a provision for 4 tubes and a ballast tube (which this doesn't use a ballast tube).

any ideas?

EDIT: I figured it out, and I figured out that my set is a model 650, which is a battery set (Farm Radio). But I have no idea what voltages I need for powering the set.

[Eliot Ness]

I just entered the # of letters it allowed me and 4 of tubes.  it came back with something close, but not exact, a Gamble Skogmo, Inc. model 650 A-B-C .  You might have to wade through a bunch of Rider's to find your radio.

https://www.grillecloth.com/sylvania/tub...ubmit&db=5

http://www.nostalgiaair.org/pagesbymodel...007098.pdf

[captainclock1988]

I found the model its a 650. B+ Voltage is 90 volts (so I could use 10 9 Volt batteries daisy-chained together) and the Filiment Voltage is about 2.5 volts or so so probably 2 D cells put together, and then a ground connection.

[David]

Some info on powering your farm radio.   https://antiqueradio.org/bsupply.htm      https://www.philcoradio.com/phorum/showt...#pid105702      https://www.philcoradio.com/phorum/showt...#pid134148

[Arran]

Hi;
  With regard to the original poster's question about battery voltages I thought I should interject. In most battery operated radios of the 1930s, up until the advent of "low current" battery types that debut around 1939 or so, the standard filament voltage was 2 volts, as that was approximately the voltage of one cell of a lead-acid wet cell battery. Do not run 2 volt battery tubes at 2.5 volts, or they will not live too long, they won't instantly burn out, but they won't last long either. I think you could find a 2 volt rechargeable battery, otherwise you could use two 1.5 volt batteries, in series, with a diode to drop it down somewhat, under load it should be pretty close for testing purposes. Building a proper battery eliminator should be the long term plan, there was a reason why they never really made many battery portables prior to the war years, it was not very practical thanks to filament current consumption.
  I don't know whom actually manufactured sets for Gamble-Skogmo, but it may have been Continental Radio & TV (Admiral), however Riders has them listed under Gamble-Skogmo so that's where the service information is to be found.
Regards
Arran

[captainclock1988]

Thanks for the info Arran! 

So I could just get a 2 "D" Cell battery clip that has the battery terminals wired in series and then wire a diode to it as a voltage dropper? Also I would prefer to try and operate this set on batteries if possible because the wiring in my house is too noisy to run something like this on AC current through a battery eliminator because I would like to try and use this for Night time DX'ing.

[Arran]

Two "D" cells won't last for too long, I was only suggesting that for testing purposes whilst you are trying to get it working. I seem to recall that someone had found a 2 volt rechargeable battery on the other forum for power G.E wet cell portables, that used to have a 2 volt lead-acid cell in the power supply. I don't think it was a NI-Cad but may have been one of those nickel iron phosphate jobs, they either got one from Mouser or Amazon. Another prospect might be an emergency light or burglar alarm battery, those are 6 volt sealed lead-acid batteries, but then you would have to drop four volts of it, maybe by using five diodes in series, or in shunt connection across the terminals, or a power resistor, or in combination.
Regards
Arran

[captainclock1988]

I was also thinking of those Sealed Lead-Acid Rechargable batteries like the onces they use in those UPS Backup supplies, I have tons of resistors ranging from 1/8 watt to 10 watt jobs and I figure I might be able to do something like that for the "A" Battery, either that or get some Lithium-Ion Rechargable "D" Cells (which do exist), and use those.

EDIT: I found these rechargeable batteries at Harbor Freight for $8 and they are supposed to be High Capacity batteries that are good for high drain applications such as electronics devices, and they can be recharged up to a 1,000 times, there's also a decent looking option at Batteries + Bulbs for $33. See links below.

Rechargeable Batteries

Rechargeable Batteries 2

[David]

You could try something like this with a small 6 volt or 12 volt gel cell for the A battery. https://www.allelectronics.com/item/udc-...-3a/1.html   There are some liner voltage regulators out there rated at 5 amps add a few resistors to adj the output voltage. Will try and get a part number some time today have a few in the workshop. I find when the power goes out during a storm or hurricane much better radio reception.

[captainclock1988]

Thanks, will look into that when you post those part numbers for me.

I was also kind of interested in looking into one of those already built battery eliminators that were sold at places like sears and montgomery wards back in the day to convert old farm radios into AC radios, kind of like the one that Radiotvphononut has on his bench for working on old battery sets (they had all of the different plugins for the various different style battery pack plugs for the different "A" and "B" battery packs that they made over the years), something like what's pictured below, but all I could find were benchtop DC power supplies.

   

[Phlogiston]

Those have some really big - and now really ugly - caps inside of them. It is a simple circuit.

[captainclock1988]

They have one for sale on ebay right now but they want $65 for it...

[Phlogiston]

Too much.

But if you want to dedicate a supply to this radio only - better than a bunch of batteries.