Early Television
Early Television
Early Television
Early Television
Early Television Early Television

Prewar Television

Richard Fernandez Replica

As a hobby, I have collected, repaired and built antique televisions and radios since I was a kid. My last television construction project built in the early 80's used a 7jp4 crt and circuitry from the late 1940's era. Attached is a photo of the completed set. Recently, I have decided to build another set using much earlier prewar circuitry and a crt from the late 30's. The 5BP4 CRT you are sending me is a perfect fit. When completed, it will look very similar to the one shown here.

By prewar technology, I am referring to having a high voltage supply accomplished without the use rf coil technology, the absence of AGC, the absence of horizontal or vertical sync locking, etc. The 6H6 HV quadrupler, the CRT high voltage divider and control circuitry and the brightness control are all early technology. I admit to not being a complete purist in deciding to use 6BA6 miniature tubes instead of 1851 octal tubes in the IF section simply because of availability and space restrictions. 12AX7 and 6AQ5 miniature tubes were also substituted for the original octal tubes in the sync separator and video output circuits for the very same reason. An extra video amp stage even had to be added in order to reverse the video polarity to deal with the older grid driven technology of the 5BP4 crt. Had I had the chassis space or the parts to use octal tubes, I do not believe that the resulting picture and sound quality would have been much different. I do believe, however, that the chassis appearance would have been much more affected. 1930's parts, as you are aware, are very difficult to find. I had a hell of a time just locating an original 11 pin crt socket.

Here is the schematic diagram.

1. All Channel Tuner - Radio-Electronics Magazine May 1949

2. HV power supply, CRT controls, video output & sync separator - Radio, Television & Hobbies Magazine September 1957; Radio News Magazine August 1947

3. Video if, 1st video amp, Horizontal & sound circuits - Motorola 7" television Model# 94BR-3017a (1949)

4. Vertical circuits - Sentinel 7" television Model# 400TV (1949)

For the most part, designing and building this set gave me a feel for what it would have been like to be a TV experimenter of the period. I got to experience the picture and sound quality of the time and a feeling of accomplishment in it's completion. If anyone viewing my set or documentation would like to experience the same they are certainly welcome to contact me with any questions.

Early Television

Early Television

Early Television

 

Early Television

 

Early Television Early Television