Tech Section: Philco Bakelite Block Condenser Data

One of the disadvantages of working on an older Philco set is rebuilding the bakelite block condensers. Nevertheless, most experienced collectors know how to do the job; normally by heating the block with a source of heat such as a heat gun until the high temperature wax (which looks more like tar) softens enough that the components inside the block may be removed.

However, the really difficult part is in figuring out how the capacitors (and sometimes resistors) connect inside each different bakelite block.

Fortunately, Philco periodically published data on their bakelite block condensers. A particularly helpful issue is Service Bulletin 289, from August 1937.

Bulletin 289 has been scanned and made available for your use here. While it does not give details for every bakelite block Philco ever made, it gives enough information that most of them can either be seen or figured out by using what is provided in this Bulletin.

The Bulletin has two pages and is presented here in Adobe PDF format. You may click the link below and view the Bulletin, and even download a copy for later use. The high resolution scan will provide good print quality on any modern printer.

Both pages of this Bulletin are available as a single PDF file. View Philco Service Bulletin 289 (requires Adobe Reader).

More information on the bakelite blocks, including complete instructions on how to rebuild them, may be found at the Philco Repair Bench.

A more comprehensive treatment of the Philco bakelite block condensers may be found in the book Philco Condensers And More, written by Ray Bintliff. The book not only gives details on all known Philco bakelite blocks, but also covers Philco metal can condensers and tone controls made between 1930 and 1936, also. These also have capacitors embedded in high temperature wax, and the repair procedure for these is much the same as rebuilding a bakelite block.

The book is highly recommended for the serious Philco collector. The price is $14.95 plus $3 shipping, and is available from Antique Radio Classified.