[GreenKeys] Bunnell Pen Register

[John Nagle]

> From: "Harold Hallikainen"<harold at w6iwi.org>
> Subject: [GreenKeys] Bunnell Pen Register

> Not quite Teletype, but it IS printing telegraph! I've been working on one
> of these pen registers.
> 
> Nameplate:
> J. H. Bunnell & Co., Brooklyn New York
> Pen Register
> Model KS-3106
> Serial Number 1 1068
> Res 150
>  
> 
> The unit seems to have a mechanical alignment issue that I have not been
> able to resolve. The shelf and feed wheel seem to be closer to the body of
> the unit than the printing wheel. Guides near the tape reel are one
> distance from the body, and guides near the feed wheel are closer. This
> results in the tape slowly working its way off the feed wheel as shown on
> the video at http://w6iwi.org/tmp/20200129_141035.mp4  .
> Note that I reused tape, so there are more marks than there should be on
> the tape.
> 
> Does anyone have a suggestion on how to keep the tape from falling off the
> feed wheel?

   I have one of those. It's for wiretapping, the early years. The
picture for "Pen Register" in Wikipedia is of my unit. Works fine.
I built a box with a phone dial, a battery, and some electronics
to demo it.

   If the tape isn't feeding straight, check the guide near the
tape reel ahead of the print wheel. That's a rectangular brass
part with a sheet metal spring clip. The spring clip should
point to the left, towards the direction of tape travel, not
downward. Then it will push the tape towards the rear of the unit,
keeping it aligned for the feed wheel.  See

https://en.wikipedia.org/wiki/File:Pen_Register.jpg

and note the position of the spring clip.

    If you need tape for it, get part ME-9284 from
Pasco Scientific. Fits perfectly.

https://www.pasco.com/products/lab-supplies/measurement/me-9284

    The legal significance of this device is explained
in the Wikipedia article. See  Katz v. United States.
The Supreme Court ruled that attaching a pen register to
a phone line was not a "search" because of the "extremely
limited capabilities of the device". That's been used to
justify total data collection of call information.

		John Nagle