[MrFixr55]

Hi RadioGuy56

First off, you are welcome!

Secondly, you could either use the speaker and output transformer out of an "AA5" AC-DC radio the used a 50L6, 50B5 or 50C5 (or any 25V or 35V variant of these tubes). The output transformer primary impedance is usually about 2.5KOhm. It won;t be loud but you could hear something.

The first radios used headphones, usually having an impedance between 1KOhm and 2KOhm. You can find decent headphones on the various auction sites (example eBay) starting at around $25-$50. I Make sure that they are at least 1KOhm. Horn speakers, using the same magnet, coil and diaphragm setup as a headphone, and also having an impedance of between 1KOhm and 2KOhm were developed. Horn speakers are available on the various auction sites but working horns in good condition tend to start at least $150 and can extend to $300 or more for Atwater Kent, Amplion or Burns, especially if they have wood or tortoiseshell horns. Cone speakers came around in about 1924-1925. Cone speakers were driven by an electromagnetic "reed, suspended in the field of a horseshoe magnet. These also had impedances of between 1K)hm and 2KOhm, but commonly were used with more powerful output tubes such as the 112A or 71A, which required a C battery to provide sufficient negative grid bias.

Thirdly, this set is similar to many other sets of the era such as the Atwater Kent Model 10, except it employs the "Neutrodyne" principle to prevent the RF amplifier stages from going into oscillation. RCA owned the patents for the super-regenerative detector and the Superheterodyne principle but did not own the patents for the Neutrodyne circuit or for AVC (Automatic Volume Control) which were held by Hazeltine Corporation (of my hometown Greenlawn, NY, about 1.5 mile from me). Don't worry about adjusting the neutralizing condensers yet; in fact, try not to disturb them. These are the wire within a tube type device behind the 2 tube sockets between the RF coils on your set.

Fourthly, the lead caps are supposed to prevent feedback or oscillation. Not sure how that works when they cover only the top of the tube. if the spring is on the outside surface and extends from a hole in the middle of the cap it is because they were designed when tubes had a tip like the miniature tubes (12AX7, 50C5, etc.). I am not sure if they help, especially with this set, and may negatively affect this set if the set was "neutralized" without them.

Now, how to tackle this unit without spending your life savings.

First off, ohm the 2 Audio transformers. These are the black boxes on the rear row of tube sockets. The primaries are usually about 1KOhm or so and the secondaries are about 4KOhm or so. Do not be surprised to find either the primary or secondary, or both to be open. Modern transformers like the P-T156 transformer from Amplified Parts (Formally Antique Radio Supply) will suffice as replacements and are relatively inexpensive.

01A tubes are plentiful on auction sites. The most expensive versions are the "BBT" (Brass base and Tipped) versions from 1921-1923 or so, which match the age of your radio. However, the phenolic based "S" envelope versions without the tip (look like a 15Watt light bulb) are fine. Amazingly, many of these 100 year old tubes still work. If you are looking for reliability more than for the correct period, the "ST" ("Sholder Tube" or Coke bottle shaped) tubes are the latest versions and likely have the least amount of hours on them. They may also be the least expensive because production of radios using 00 and 01 series tubes stopped around 1927-1928. Shoulder Tubes were introduced around 1933, making these tubes definite replacement tubes and not OEM. Considering that these radios were likely put into storage shortly after ST type tubes were installed make them a good bet IMHO. Expect to pay be$15-$25 per tube. You can plae a "Wanted to Buy" ad in the Phorum in the "Wanted" section of the Trading Post on the Phorum. Go to the home page and scroll down to the bottom and you will find the link.

The RF coils and tuning capacitors are likely good unless the primary of the first RF coil was blown from a lightning hit. Not to worry, if you have a very strong AM station, connecting a wire to the primary of the detector coil will likely allow signal to be detected.

I may have stated previously that you can use a 6V source or even the 5V output of an old computer power supply and 10 9V batteries to power the set for now. If you find yourself collecting more of these early battery sets, consider buying either a kit or fully assembled power supply. or building one from one of the many schematics and plans for these that can be found on the 'net. You can find these on e-bay for as little as $75 for a kit. The "gold standard" power supply for these radios is the ARBE III. Available from A tique Radios LLC (arbeiii.com) Unfortunately, the price of these have increased to $225 plus tax and shipping, but I am very happy with mine.

The 00A and 01A are both covered in some detail on the 1932 version of the RCA Receiving Tube Manual that I provided the link to in my previous post. Let me know if you have difficulty downloading and saving that manual to your computer. Download the 1940 version also, but use the 1932 version for this project.

Good luck and keep posting!!