A Sparton Model 69 Equasonne

BY ALTON A. DUBOIS
Web Edition

Just when you think that there are no more old radios to be found, a golden opportunity pops up. (Editor)

Several months ago, I visited the local antique shop in town, just to look around. I had gotten several radios from him that badly needed work, so most people did not pay attention to them. On the second floor level, I found a radio that was mixed in with a bunch of furniture. The dealer wanted $70 for it. On closer examination, I found it was a 7-tube Sparton Model 69 Equisonne of 1928. I was familiar with that model but had never owned one, so I bought it.

He put the radio in my car and said, ³Wait, there¹s more.² And he brought out the console speaker, which turned out to be a Sparton Model 29 cabinet speaker -- all for $70! Both the radio and companion speaker cabinet were in good shape. When I tried the radio at home, it worked for about 30 seconds and quit. I checked the speaker, an 18" cone type, and found it was OK. But, the magnetic armature assembly needed cleaning, so I took it apart and cleaned and adjusted it. When I tackled the radio, it was a job to unbolt and remove the three separate chassis. This thing is built like a tank.

Since the non-powered tuning unit was covered with dust and grime, I started to remove the capacitors to clean them. What a job! Thirty-nine screws and nuts had to be removed to get the unit out. I separated the capacitors from the coil unit and cleaned them in my ultrasonic cleaner. I reassembled the unit with the 39 nuts and screws.

Figure 1. The Sparton Model 69 radio atop its companion Model 29 cabinet speaker.

This unit feeds a broadband RF unit that has six tubes and assorted coupling coils. What killed the operation was some shorted bypass capacitors. I replaced them all with 0.1 mF 400 v. capacitors and tried it again, only to discover that the audio transformer was also open. It had been replaced previously. I replaced that with a transformer I got from Antique Electronic Supply.

I tried to operate the three chassis on the bench with foot-long jumper cables connecting the chassis together. The set acted very unstable and would not tune right. On investigating, I discovered that the grounding connection in the cabinet was a polished brass plate that evidently had less inductance than the jumper cables. When the three chassis were in the cabinet and grounded properly, the radio settled down and operated well.

I had been corresponding with Dale Davenport about the set, and he sent me a circuit diagram and some suggestions on the audio output. After I got the radio working, all the tubes were found to be good, and all the RF tubes were the original Type 484s. The only change was a Type 50 in the output that should have been a Type 585.

Bingo! I remembered that I had a box of old tubes stored away. In it, I found a Type 585 tube that was good. I will store the Type 50 for future use. I looked up the 484 and the 50 in Antique Electronic Supply. catalog. The prices are unreal.

My restored Equasonne, shown in Figure 1, is now residing in my family room and plays like the Philharmonic Orchestra.

(Alton A. DuBois, Jr. 67 Peggy Ann Road Queensbury, N. Y. 12804)

Alton DuBois has been interested in radio since working for an engineer after school in the 1930s for 10 cents an hour. Having worked in TV service for RCA since 1948, he is a founding member of the RCA Retirees Club. His collecting interests include antique clocks, as well as radios.