[Elrick]

I'm working on a little Detrola model 247 table top job. I understand Detrola manufactured literally hundreds of different radios under their own name and others. This radio is pretty simple, 4 tubes and a ballast. The ballast is badly blackened and has big loose parts rattling around inside, so it's almost 100% likely to be faulty. I can't read the ID on the ballast, but hand written on the chassis it reads. BK55BG. The other tubes are also properly scribed on the chassis and agree with the marks I can read on the tubes so I tend to beleive the ballast really is a BK55BG. I have been unable to locate this particular Detrola model schematic from Nostalgia Air but they do have a schematic which seems to be identical it's listed as Model 208A.

http://www.nostalgiaair.org/PagesByModel...003925.pdf

I have been unable to find a replacement for the Ballast or any cross reference number. I did find some "univeral ballast" replacements at tubes and more :

http://tubesandmore.com/

Any thoughts on finding a replacement. or if I'm on the right track? And no I haven't powered up the little Detrola yet, just gathering my parts list. Thanks, hope someone can steer me in the right direction.

[Elrick]

Here are a couple of pic's of this little jem.

[Image: http://i103.photobucket.com/albums/m140/...5_1074.jpg]

[Image: http://i103.photobucket.com/albums/m140/...7_1076.jpg]

[Image: http://i103.photobucket.com/albums/m140/...2_1081.jpg]

May look just another cheap old radio but it was my mother's childhood radio and I know she would get a kick out of hearing it play again. And can anyone figure out why the dial shows a mirror image of its' self below. There doesn't seem to be any difference, or am i missing something obvious.?

[Ron Ramirez]

Vacuum Tubes, Inc. lists a JFD type B as a universal replacement for your ballast, plus many others. You may want to talk to Jim Cross (the owner) about this?

<!-- m --><a class="postlink" href="http://www.vacuumtubesinc.com/">http://www.vacuumtubesinc.com/</a><!-- m -->

His site has a "Contact Us" page.

A year or so ago I had to restore a Detrola for a friend. It had two of those BK55BG ballast tubes. Fortunately they were both still good.

I think your dial scale was just made that way for two reasons: One, for ease of tuning - the top scale is divided by fives (55, 65, 75, etc.) and the bottom one by zeros (60, 70, 80, etc.). Second, just for style's sake.

[Jim Berg]

That ballast appears to be black on purpose. Could be loose cement in the base that is the rattle. I could look it up for pin out but I would guess you should have resistance between 3 of the tube pins. Do not check on a tube tester! If filaments in the set light and the dial lamp lights the ballast is good. If getting a universal replacement, beware that some of the socket pins on the tube socket could have been used as "Tie points" and may cause a problem with a different ballast.

[Elrick]

Replacement ballast BK55B arrived, had to pay more than I wanted but apparently these are fairly rare. Haven't tried the radio out as yet, still waiting on my lastest parts order from Just Radios. Seems like I always leave something out and then have to order another $20 worth of parts just to get the $0.49 part I forgot to order on the previous order. At this rate my supply of spare parts is growing rapidly.

[exray]

Once you build up an inventory shipping costs (and minimum order costs) go down If I need two of a 30 cent part I order 4 or 5. It doesn't take long to build an inventory so that you're not spending so much time and money going back to the well.