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Re: Kollsman periscopic pendulous sextant
From: Gary LaPook
Date: 2008 Aug 31, 21:00 -0700

Gary LaPook wrote:

You do not need 28 volts to illuminate the Kollsman periscopic sextants.
All you need are a couple of Caltronics number 328 miniature lamp light
bulbs which are the same size as the 28v bulbs originally installed in
the sextant but which operate on 6 volts. I made up a 6 volt power pack
for mine using 4 AA batteries which I attached to the back of the
averager with velcro. You can also use bulbs designed for 12 volts that
are Caltronics number 330. You could then make a power cord to use a
cigarette lighter socket for power.

I have scanned the "Sextants" section of Air Force Manual 51-40, "Air Navigation" (1955 and 1960 editions) and posted it on my little web site. This is good info for owners of U.S. bubble sextant models A-10, A-14/AN5851-1, A-15, MA-2, and Kollsman periscopic. The MA-1 pendulous mirror sextant is also covered. The page is 990 k, but 95% of that is the images. If you have a slow connection, it may be best to turn off graphics in your browser, read the text, and individually download the images you want. http://home.earthlink.net/~s543t-24dst/airnav/index.html My new HP C3180 did the scans. It's a combination inkjet printer, flatbed scanner, and copier, priced at $100. This is my first experience with a scanner. As far as I can tell, this unit does a good job, especially considering its low price. To input text, I scan it in black and white mode and request the output as a .txt file. (OCR software is bundled with the unit.) Then I paste that into an HTML editor and clean up the OCR typos by hand. The biggest problem by far is that a hyphen at the end of a line invariably causes letter doubling. E.g., ad-ding (with a line break after the hyphen) comes out as "addding". Nevertheless, this process is enormously more productive and accurate than hand typing. Some of the "typos" are exactly what the original says. For example, the periscopic sextant section has a true heading formula: TH=TB-8RB [sic]. I haven't fixed those mistakes, since my objective is to accurately reproduce the original. The C3180 can produce *much* sharper scans than the images on the web page, but more resolution means slower page loading, especially for users on dial-up. In addition, the physical size of some of the images on the screen becomes annoyingly large. So, I set the resolution just high enough to generate adequate images, and some I omitted entirely when I felt the text was understandable without them. It's fortunate that AFM 51-40 is loose pages bound by metal clips. The book comes apart easily. I imagine conventional binding would cause a lot of trouble getting the pages flat on the glass. I may put more of this manual online. If you have a burning desire to see a particular topic, speak up. I have only one volume from the 1955 edition, but all three volumes of the 1960 edition. It captures an interesting time in air navigation. The sextant, astrocompass, and 4-course radio range are in there, but so are VOR, TACAN, and Doppler. -- I block messages that contain attachments or HTML.

More options Sep 6 2006, 10:07 pm

Paul Hirose wrote:

I have scanned the "Sextants" section of Air Force Manual 51-40, "Air
Navigation" (1955 and 1960 editions) and posted it on my little web
site. This is good info for owners of U.S. bubble sextant models A-10,
A-14/AN5851-1, A-15, MA-2, and Kollsman periscopic. The MA-1 pendulous
mirror sextant is also covered.

The page is 990 k, but 95% of that is the images. If you have a slow
connection, it may be best to turn off graphics in your browser, read
the text, and individually download the images you want.

http://home.earthlink.net/~s543t-24dst/airnav/index.html

glapook@pacbell.net wrote:

That is exactly what is used with the A-10 sextant, 4.5 volts from
three size "D" batteries. If you have one of the more modern Kollsman
sextants that use an electronic averager you do need to supply 28
volts to the averager since they won't work on less. For use in an
airplane, you can make a 28 volt power suppy with one integrated
circuit and a small amount of soldering. The IC converts 12 volt DC to
28 volt DC and costs about $25.00. I made one and can find the source
for this IC if anybody wants to do the same. You can also get 27 volts
out of 3, 9 volt batteries wired in series. This works fine for the
lights but the averager uses about 150 ma so these betteries don't
last long powering up the averager. And they are expensive.
You can also replace the 28 volt bulbs, or in your case the 3 volt
bulbs, with 6 or 12 volt bulbs that are the same size and power them
up with other battery combinations or with a cable to your lighter
socket in the plane. If anybody needs the source for these other bulbs
I can find it again. I think I posted all of this information on bulbs
and on the IC about a year ago so you can probably search the archive
for it also.

gl

On Aug 31, 6:56 am, werner <w....@gmx.net> wrote:

Actually my Kollsmans are Euopean license builds (1 from Kollsman-
Germany and the other 2 from Kollsman-UK, and had been used in the
respective air forces). Those sextants have a 3 Volts lighting system.
28 Volts only go into the gimbal aircraft mount. Within it the voltage
is transformed into 3 Volts to go into the sextant. The usual method
(when not installed in an aircraft) is to use a modified flashlight
(instead of the bulb there is a connector for a cable) with 3 D-cells
(flashlights were provided in the storing case).

Werner

On 31 Aug., 04:49, glap...@pacbell.net wrote:

BTW, if you need a 28 volt power supply for using your sextant at home
just go down to Home Depot and buy a water sprinkler system electric
transformer which puts out 28 volts and is cheap.

gl

On Aug 27, 12:12 pm, werner <w....@gmx.net> wrote:

Hi,
Has anyone a manual for this sextant? I need one for the "non-bubble"
type, but with the pendulum. I have three of these sextants (two good
ones, one needs overhaul).

Thank you.

Werner

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