Zenith G725

Manufacturer: Zenith Radio Corporation, Chicago, Illinois
Model: G725 (7G01 chassis)
Approximate Date Of Manufacture: 1950
Type: AM/FM table radio
Tube lineup: 12BA6 (3), 12AT7, 12AU6, 19T8, 35B5
Status: working, restored
Where purchased: ebay, January 2007

Description

This is a larger than average AM/FM table radio with bakelite case. It is a relatively early model for FM, which is mono only, and has no AFC. It has 7 tubes plus a selenium rectifier in the power supply. The schematic is in Riders volume 21 pages 14-17 and Beitman's 1950 page 188.

It has a very attractive large dial in the center. The 7 inch speaker is mounted behind the tuning dial. A knob in the center of the tuning indicator is a tone control (and is easy to overlook). It has a carrying handle on the top.

FM tuning uses variable inductors mechanically connected to the same variable capacitor used for AM tuning (a cam moves cores in and out of the coils).

The dial lamp is neon and illuminates a small glass jewel next to the power/volume knob. There is an AC interlock on the back like the type used for TVs.

The radio more or less worked as received when briefly powered up. I put on new cord, replaced some rubber covered wire, and replaced all electrolytic and paper caps (at some point a new electrolytic cap had been paralleled in with the old one). It was tricky to get at some of the paper caps; there were 12 in all. One was a "black beauty" that some guitar amp audiophiles swear by (it showed high leakage when tested on my leakage tester).

Despite their reputation for being unreliable I kept the selenium rectifier - it looks similar to a fuse and is in a holder.

When cleaning the case a lot of brown came off onto the paper towels. Some brown is normal but this amount indicates it had been exposed to tobacco smoke for some time.

I did not realign the radio because it was working well and some of the components were sealed in place.

The radio has good sound, thanks in part to the large speaker. It is quite sensitive on FM even with no external antenna. Tuning on FM is critical because there is no AFC. Like many Zenith radios, it is considered a classic both for its appearance and its electrical performance.

Pictures

See this page.