Odd item found
 

Here's a new one, for me. This is an Eby BG-1 Bar Generator that is apparently placed between the CRT socket and the CRT. I don't have a BW set to try it out on, but by the description, no other equipment is needed.

Anyone every use one, or know the full story?

That is pretty neat! I too would like to know how and how well it actually worked.

IIRC I read about them in some period magazine (an AD I think), I wondered how they worked, and doubted that any actually still existed....Guess I was wrong.

It appears to be a socket adaptor to enable using a 110 degree test CRT on an older style 50-70-90 TV for bench service.

The plug and socket are the same, and the catalog shows it in a different section than the adapters and extenders. It's definitely a tester (bar generator) of some sort, not an adapter. I came into TV servicing in the late 70s, so the old tube black and white (big neck) sets weren't among items we serviced.

Fascinating. Crack it open! :)

It only mentions vertical adjustments, not horizontal, so I am guessing that it does some fun shenanigans with the (AC) filament "signal" to put horizontal bars into the cathode or grid of the CRT. These oddball items are fascinating to see now, like the gadget that went under damper tubes to increase the picture width.

That was my first thought, it looks just like the sockets that come with the 8YP4 test tube, except this one is 12 pins on both sides so it can't be for that.

Better find a black and white set and try it. :)

Yeah, I got one of those too. ;)

My username is not a fluke....

I'm guessing that it contains a simple 2 transistor multivibrator circuit, producing a 300-400 Hz square wave that is injected into the grid/cathode circuit of the CRT, to produce evenly spaced black bars on the screen... Any other guesses?

jr

It contains a cap and a resistor - I'm reverse engineering, but that is all that is visible - some kind of an integrator, I guess. The resistor is 2 Megs, 1/2W carbon comp.

Someone mentioned coupling of the filament voltage to the cathode or grids - that probably is what is happening. More later!

In order to produce multiple bars, it'd hafta run at some multiple of the line frequency. Seems like that would require an active device of some kind. Tunnel diode maybe?:saywhat:

Missed that.

Fascinating! How does it manage to sync anything with the sweep?