Restoration of a Silvertone Low-boy (Chassis Type B109) Gerry O'Hara VE7GUH 2007

	Restored Silvertone Low-boy cabinet.

Here is a fully-restored but as-yet unidentified Silvertone console model dating from 1931. The chassis installed in the set is Type B109 and this was fitted in several Silvertone model numbers (Beitmans 'Most-Often-Needed' manual notes Models 1320, 1324, 1326X, 13869, 1454, 1458, 1531, 7004) - the only difference likely being the cabinet style. This was frequently the case for radios manufactured for retailers such as Sears-Roebuck & Co. such as this one, retailed under the Sears 'Silvertone' name.

The B109 chassis is interesting technically in that it is an example of an early superhet design using remote cut-off screen grid tubes in the RF and IF stages. It has a #35 (remote cut-off screen-grid) RF amplifier, a #24 mixer, #27 local oscillator, #35 IF amplifier (at 175kHz) and #24 detector/reflex first AF amp and a pair of paralleled output tubes (#47s).

This particular set was restored by Gerry O'Hara and Pat Jones at the SPARC museum in Coquitlam BC in 2007. The radio was rescued from the scrap pile at the American Museum of Radio and Electricity in Bellingham, Washington by Gerry in 2006 and was in a very dilapidated state when found - the feet were rotted away probably due to standing in water for many years, pieces of veneer were missing and the original finish was very rough. Replacement feet were made from some scrap table legs, damaged veneer was replaced from veneered areas of the set that did not see light of day (edges of the speaker baffle board), the set stripped and re-finished with semi-gloss lacquer and finished to a beautiful lustre with paste-wax. Replacement speaker cloth was purchased from 'Radio Daze' and the dilapidated and rotted cabinet morphed into a superb piece of furniture.

	During restoration.

Restoring the chassis was rather problematic: the main issue was that the power transformer was obviously burnt-out, depositing tar on the chassis, so this was removed and discarded. The set uses 2.5v heaters for all tubes apart from the #80 rectifier (5v) and there are not that many transformers these days that cater for these requirements as well as the correct HT voltage and current needs. However, Radio Daze carry a suitable transformer (RDX-200) and one of these was purchased and installed. This transformer includes a thermal cut-out that should offer protection if a fault develops in the set at a later date. The by-pass capacitors for the set are installed in a large, solder-sealed metal can and rather than cut this open and re-stuff this, the simpler solution of installing individual replacement by-pass capacitors was taken, along with installing replacement under-chassis replacement 16uF and 8uF filter capacitors in the power supply, leaving the metal cans installed for cosmetic reasons only. The chassis was given a good clean with alcohol and wiring replaced where necessary, and a fuse was installed to offer additional protection. Three resistors were out of tolerance and were replaced, the rest tested within tolerance and so were left in place.

On powering-up, the set 'came alive' right away - probably for the first time in several decades - bringing in all local stations on a couple of feet of wire. On testing with a longer antenna, the set was found to have good sensitivity and looks and sounds good - much better than being destined for the dumpster!

Chassis before restoration ...

... and after.

Wiring before ...

... and after.

Finished chassis from the front.

All done ...

... and from the rear.