The PHILCO Phorum
Jackson Bell model 68 Tulip - Printable Version

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Jackson Bell model 68 Tulip - Bill Cahill - 01-11-2011

Didn't know where else to go here.
I need help. I need a paper schematic, a good picture of original knobs, and, a rebuildable speaker for this set. It uses a Magnavox model 138 8" speaker. What can anyone tell me about this set, and, can anyone help me get parts for it?
I really want to restore it.
What year was this set made, and, what is the quality of this 8 tube radio?
I had replaced fried power transformer in it years ago, re capped it, and, put a temporary spkr. on it.
It would only play one station very weakly when I put my hand on secondary coil of first RF. And, that, same station all the way accross the dial.
What could be wrong?
Thanks.
Bill Cahill

Re: Jackson Bell model 68 Tulip - rghines1 - 01-11-2011

Schematic emailed.

Hearing only one station generally means the local oscillator is not running. A strong nearby station is able to force its way in enough to be heard. Richard

Re: Jackson Bell model 68 Tulip - Glenn Roberts - 01-11-2011

I'll post this link, I'm sure you've already looked there, but it does show the knobs.

http://www.radiomuseum.org/r/jackson_be_68_2.
Glenn

Re: Jackson Bell model 68 Tulip - Bill Cahill - 01-11-2011

Please forgive my lack of knowledge. I am familiar with I F circuits, but, Haven't had enough experience on RF sets. Didn't know they used an oscilator on rf sets.
Thanks.
Got e mail, and, schematic. Many thanks.
Bill Cahill

Re: Jackson Bell model 68 Tulip - Ron Ramirez - 01-11-2011

There is no local oscillator in this set. It's a TRF, not a superheterodyne.

I have no idea when it was made, but it seems to be nicer than a lot of TRF sets of the late twenties/very early thirties...three stages of RF amplification, and push-pull 45 outputs.

I don't see much in the way of components between RF stages. RF coils, the 0.25 uF cathode bypass cap that is common to all of the RF amplifier tubes, resistors in the front end and voltage divider network, tubes...any of these could be causing the problem. Also a bad field coil, or filter choke. Check the voltages. You are lucky in that Rider's gives the voltages. A lot of the schematics for smaller companies such as Jackson-Bell didn't even give component values, let alone socket voltages.

Re: Jackson Bell model 68 Tulip - Bill Cahill - 01-11-2011

Actually, it's 4 rf stages. The radio dates to 1931.
It was a well made set. I'm missing the spkr. Made some jury rigs to try set.
Bill Cahill

Re: Jackson Bell model 68 Tulip - Ron Ramirez - 01-11-2011

No, Bill, it has three RF amplifier stages. The fourth "stage" is the detector circuit.

Re: Jackson Bell model 68 Tulip - Bill Cahill - 01-11-2011

Icon_redface Thanks, Ron. I thought this one had a seperate detector. On the 1928 Edisons with 3 rf tubes, they used part of the 27 as the detector.
I have to familiarize myself with this schematic.

Oh, by the way. One of the big 3 knob dealers contacted me the other day. She offered me a set of bakelite knobs she says are for my set. The only difference is the picture of another set I saw shows a 3 step knob, and, these are two steps. Otherwise, they look exactly like them. Any comments here?
My friend, Mr. Detrola from ARF says since he's seen variations of original knobs on different sets produced by this companny, that it's very plausable, in his view, that these are yet another variation.
Bill Cahill