Federal 17/173 small dome question

[billforbush]

This is probably a dumb questions, but did the older Federal 17 and 173 lights with the smaller dome use the same base with a different gasket or a smaller diameter base? I don't have one of the smaller ones in my collection as yet and wondered if I could out a smaller dome on a large-dome model?

Thanks

Bill

 

[empire5150]

Hi Bill. The smaller dome (earlier) beacons had a smaller diameter opening in the base. When the smaller diameter domes ran out, Federal instructed users to cut the opening larger to replace with the larger dome.

 

[Maxim2Eng]

Federal went with the larger dome/base as they introduced the 3 & 4 bulb lights (173, 174, 175 & 176) in the late 50s/early 60s. It is a subtle difference as the newer domes had vertical sides to accommodate more bulbs--the older 17 domes had a slight slope outward toward the base/more narrow toward the top. Also, the skirts had a broader "shoulder" at the domes before tapering to the skirt.


The earlier skirts were expected to be trimmed to fit the contours of 1950s era vehicles and the mounting instructions proclaimed the center of the roof forward of the drivers head to be optimum (that would later be change to over the drivers head in the late 60s where flatter roof contours did not require trimming).

 

[stansdds]

Yep, the larger dome does require a larger opening in the top of the skirt and a slightly longer dome gasket.  The larger dome was first introduced in 1958 with the 4-bulb, oscillating, model 174 Super Beacon Ray.  Around 1964 Federal started using the larger dome on a few 17's and 173's, but in 1968 Federal stopped making 17's and 173's with the small dome.  From then on, all 17's and 173's would be made with the larger dome.