Engineering Slide Rules Have Become Very Collectible

[W2DU]

I still have all the slide rules I ever used, starting with a 10" wooden one while in 10th grade. Later in the year my Dad gave me K&E log trig. While in the Navy I purchased K&E Log-Log Decitrig that I used for many years, but later I purchased a Picket & Eckel yellow aluminum rule (also Log-Log Decitrig) that I used entirely during the development of the TIROS 1 antenna array. Used that rule along with a circular Smith chart slide rule.

Then in 1971, like a lot of others on this thread, I purchased the HP-35--what a difference it made in the time required to make a calculation and in the precision!!!

Now using an HP-15C, HP-34C, and an HP-42S--still fun  to use  'em.

Walt

PS--Rick has my HP35 in his vintage collection, but I still have an HP55--good as a timer.

[n4wc]

In the past(around 20yrs ago) when doing special wartime training at sea and all, and I mean all oscillators on board ship were required to be turned off; the necessary calculations were done via "slipstick".  I don't know if this practice is still done!

Cheers

[K3ZS]

Just found my college K&E.    The only thing I remember was how to multiply and divide.    I think I had a book that was purchased with it that explained how to use all the other scales.

[Ralph W3GL]

   Walt mentioned the circular Smith Chart rule.  Last evening I checked
   my book case and in among the volumes was this 8.5 x 11 red folder
   with a stylized "A" on the front for Amphenol (Amphenol RF Calculator)
   with a price down in the right corner of $3.00.   Probably the best 3 buck
   investment I made in 1968 or so. The thing was copyrighted in 1966...

   The rule in there is 23cm diameter with great definition and on the back
   there's the Smith Chart in all its glory.

    Walt, was that the one you had?   I had mine in my brief case while at
    Astro but never needed it for what I was doing on the NavSat final amps.

[W9GT]

I still have several slide rules I used back in the "good old days" plus a box full of nomograph charts (rectangular and circular), many with little windows that you moved around depending on what you were calculating. Even have a "etch-a-sketch" type pad with Hammarlund's name on it in that box.

I also have a bunch of those "calculators" with linear and circular scales for all sorts of things.  Used them in the 60's/70's for antenna and transmission line calculations, as well as ERP calculations and several were set up to do various calculations for microwave system design.  Wow, things have sure changed since then!  Computers and all sorts of software have replaced all those analog devices.  We also had all kinds of scales that we used with 7.5 min US Geological Survey maps to plot paths and calculate HAAT, etc. As well as locate coordinates. Ah...life before Google and GPS.

73,  Jack, W9GT

[W2XR]

The concept and invention of the slide rule dates back to (IIRC) the 1500s, by an wealthy Scottish gentleman farmer named John Napier. His hobby was mathematics, and he was the discoverer of the natural logarithm, also commonly referred to as Naperian logarithms. Another mathematician named Henry Briggs later discovered the concept of the commonly used base 10-e logarithms and scientific notation. Napier is also credited with improving the concept of the place-holding decimal point.

At any rate, Napier came up with the basic idea of the slide rule for performing mathematical calculations rapidly; his invention was originally called Napier's Bones, as the numbers were engraved on lengths of ivory. By moving the ivory pieces back and forth, Napier was able to perform his calculations, and this became the forerunner of the modern slide rule. I remember Napier, his discoveries and inventions, from an elective course I took back in college entitled, "The History of Mathematics".

The only issue with the slide rule, if you want to call it an issue, was the obvious necessity to manually determine the placement of the decimal point; on lengthy calculations, and unless you had a really good memory, you still needed paper to record each successive result, as there was no "store" feature (as found on modern electronic calculators). Yet, of course, generations of engineers and other users of the slide rule grew up with this requirement, and it was part of the entire calculation process.

Just a little slip-stick trivia.

73,

Bruce

[W2DU]

Ralph, I'm attaching a scanned copy of the Smith Chart slide rule and one of the Amphenol RF slide rule with the Smith Chart slide rule on the reverse side. Is this Amphenol chart the one like yours ?

This Smith Chart slide rule is what I used beginning in 1957 while developing the antenna array for the TIROS 1 weather satellite.

Walt

[W2DU]

I'm attaching here a pic of my collection of K & E rules. By collection I mean those I've used over the years. The dark brownish one on the left hand side was my first rule, acquired when I was 13, for Advanced Algebra, 10th grade in 1932.

The second pic is of the Picket & Eckel that I used beginning in 1957 while developing the antenna array for TIROS 1, the World's first weather satellite. In 1971 the slide rule was replaced by the HP-35 calculator.

Walt

[N4LTA]

The two best bamboo ones were the K and E and the Post.

In my first EE course EE201 elementary circuit analysis  in 1971 the HP 35 came out. I believe they sold for $499 which was more than a years tuition at NC State.

You could do polar to rectangular and vice versu in a 15 seconds (not direct like the later ones) and with a slide rule it took several minutes - The killer quiz for that class involved adding  and subtracting polar coordinates and multiplying and dividing rectangular numbers. The answers had to be converted again. The quiz was near impossible with a slide rule and usually everyone failed it and depended on a heavy curve. Two rich kids had the HPs and destroyed the curve.

The head of the undergraduate department was a old Annapolis  professor and was a hard azz. He did the right thing and allowed the HP 35s to be used but it was hell on us poor boys.

[Ed/KB1HYS]

Ed said:

Still have my E-6B flight computer (Whiz Wheel) from the flying days,

That wouldn't be like an EA-6B type aircraft now would it? We had a squadron jump on-board when we would INCHOP the Med out of Rota, Spain.

Ha!  I wish!  no it's just the nomenclature for the standard navigational circular slide rule.  Used to perform all sorts of calcs. like fuel consumption, crosswind correction, true airspeed, Altitude corrections etc.  and it could add, subtract & multiply too!  You could be pretty busy as a student pilot on a solo cross country...  

[W2XR]

I'm attaching here a pic of my collection of K & E rules. By collection I mean those I've used over the years. The dark brownish one on the left hand side was my first rule, acquired when I was 13, for Advanced Algebra, 10th grade in 1932.

The second pic is of the Picket & Eckel that I used beginning in 1957 while developing the antenna array for TIROS 1, the World's first weather satellite. In 1971 the slide rule was replaced by the HP-35 calculator.

Walt

Hi Walt,

Great stuff.

A lot of wonderful engineering achievements were performed by you with the assistance of those slide rules.  To a large extent, they were the tools of your trade before the advent of modern electronic calculators.

Thanks for sharing that photo. I think you and I (and probably many other participants of this forum) may be somewhat similar in that we never get rid of certain meaningful things that go back to our early childhood, such as that slip-stick you first acquired back in 1932.

I first learned the basics of using a slide rule in 11th grade chemistry class, where I think we used it to calculate PH and Avogadro's Number. I borrowed my Dad's mahogany K & E slide rule for that class. As I mentioned earlier, in college I acquired my K & E Log-Log Decitrig, which I still have to this day. For some reason, and for the past 40 years, I always thought it was made from bamboo, but a perusal of the slide rule website I visited over the weekend, (and where I provided the link in my initial posting on this topic) revealed it was made of mahogany. I learn something new every day.

73,

Bruce

[Ralph W3GL]

   Walt,

   Yes, that is the one like I have stashed away on the bookshelf...
    I had the rule, in the red folder, stuck in the pocket on the inside
    of the lid of the brief case.  I carried that case till it finally fell apart.

    Yesterday, I had lunch with my oldest son and asked him if he
    knew what happened to my Hemmi Log-Log Decitrig and he said I
    gave it to him years ago.  If he says so, I guess its so...

    I also, have my dad's old K & E with the S, L & T read off the
    back of the slide and only the A, B, C & D scales on the front side.
    No model number on it, just the patent date, June 6, 1900 and  the
    number 89023 on the back end of the slide and on the side of the
    body...  

    This rule must have been a delux model, as it is Ivory inlayed over
    mahogany and has the patent date 6.7.15 on the edge of the curser.

    My dad was in school in the early 20's and I suspect he got the rule
    from his dad.  I do recall using this rule in school; was a lot easier to
    read the way its  laid out, for basic calculations...  

[Vortex Joe - N3IBX]

^{A good back-up to have in case of HEMP.}


HEMP Help End Marijuana Prohibition    

I wholehearthedely concur!

Joe Cro N3IBX

[W7SOE]

I took the last slide rule class offered by my high school.  When we were done with a problem we would check our answers using a couple of TI (I think) calculators located at the back of the room!

Rich

[Vortex Joe - N3IBX]

Hello All,
           I'm curious, does anyone here have the 1932 edition of the ARRL sliderule calculator for RF problems and equations? I have at least one and maybe even two original ones around here somewhere.

There was a Radio Store in Pittsburgh, pa (on Grant St?) that put out something similar around the same time as the ARRL did. It too is facinating and even useful.

What surprises me the most, is how damn accurate these things are. Like a Measurements, or Millen, etc. GDO, they're indespensible to have around the shack!

Regards,
Joe Cro N3IBX

[Tom WA3KLR]

Hi Joe,

The 1936 HB has 6 types of Lightning Calculators - A through F.

I have my father's Type E here, copyright 1935, for parallel resistance and series capacity.  On the back of it, it says "(No. 11E in the A.R.R.L. Series entitled The Radio Amateur's Library).  Price 50 CENTS Postpaid"

_._

[Vortex Joe - N3IBX]

Tom,
      That's terrific and I asppreciate you posting the pic! I have to see what condition my 1936 handbook is in, and if it has the calculators in it!

Hope all is well and "GL in the contest OM"!
Joe N3IBX

[Vortex Joe - N3IBX]

Ed said:

Still have my E-6B flight computer (Whiz Wheel) from the flying days,

That wouldn't be like an EA-6B type aircraft now would it? We had a squadron jump on-board when we would INCHOP the Med out of Rota, Spain.

Mike(y),
           The next time you're down my shack, please remind me to show you the officious US Army Air Corp flight speed computer. It's a rather complex slide rule(s) that you can use to calculate true air speed (so it says).

The date of acceptance on it is 1945. Just the thing you need in your restored B-29! God, I love the looks of that plane!!!!!!

Mod-U-later,
                Joe

[Tom WA3KLR]

ARRL Lightning Calulators (from 1936 Handbook)

Type A - Radio Calculator
coil design (I believe there were several editions of this.)

Type B Ohm's Law Calculator
Includes power and dB

Type C Wire Data Calculator
Lots of wire table type of info

Type D Decibel Calculator

Type E Parallel Resistance/Series Capacity Calculator

Type F Resistance Calculator
"This calculator makes an ohm-meter of your voltmeter."

[N8LGU]

    When I was going to take my Advanced ticket, I had been practicing doing the calculations on my HP-20S calculator. I was running late to the session and as I was heading out of the door, I noticed the batteries on my calculator were dead. I spent several minutes looking for my daughter's calculator. No joy. So I grabbed my Pickett 500 ES and hurried off to the session. After starting the exam a young VE walked up and told me I couldn't use "that thing" as it would be considered cheating! As the debate heated up, An older VE walked up and set the younger VE straight. No wonder so many younger hams don't like analog dials- probably can't read a watch with hands!
    I passed the exam. Maybe I was the last Ham in America to take the exam with a slide rule!