[Antennas] L & C Calculator

Sun, 21 Apr 2002 16:55:22 -0500

here you go....from sandy.....

Reply-To: <[email protected]>
From: "Ron D' Eau Claire" <[email protected]>
To: "Sandy W5TVW" <[email protected]>, <[email protected]>
Subject: GB> Coil and Reactance Calculators
Date: Thu, 13 Dec 2001 12:56:08 -0800
Importance: Normal
Sender: [email protected]

I just picked up my genuine replica Allied Radio "RF Resonance and Coil
Winding Calculator" to check the tuning range of a circuit and it reminded
me to say a BIG "Thanks!" to Sandy, W5TVW, for providing the images for the
calculators on his website (the URL's are below).

When he announced them I took a peek and recognized the Allied one as
something I had many years ago, so just for fun I downloaded the images and
printed it out on my ink-jet printer using 110 pound cover stock. Made the
slide up of two sheets stuck back to back so it has some real body, and then
fashioned two double thickness 'shims' to act as guides and keep the outside
covers from binding on the slider. Trimmed out the bits with a sharp X-acto
knife and stuck it all together with a glue stick.

It looked so good that my wife picked it up and said, "Wow! This is a real
antique!". I had to make her feel for the rivets and see that they were only
images to prove it wasn't 'real'. With the shims running the length of the
calculator acting as guides for the slider, I suspect that it works better
than the original with the riveted construction.

Then I discovered how USEFUL it was. In these days of calculators pounding
out answers to 6 decimal places, it's really FB to be able to wiggle the
slide and see in an "analog" way (like my brain works) how the size or turns
of a coil affect its inductance, or simply scan the scale and see what
tuning range my 25-350 pf variable will have with any size of inductance.

I went right back and got the Shure calculator too. They are so much more
friendly and fast to use than my calculator, and the results are as accurate
as anything I need to make a circuit perform like I want it to.

I'm going to save the images because I can see that I'll wear the ones I
made out before long. Besides, there's a whole generation of hams who don't
know about them. Seeing a new builder punching in strings of numbers to find
the resonant frequency of a circuit on his calculator, I had to give him a
set. He was AMAZED at how easy it can be. I'll probably give more copies
away as time goes on.

Back in the "pre-calculator" days I found the design of nomographs and
specialized slide rules like this a fascinating mixture of artistry and
engineering. It seems to be an art that has died out under the onslaught of
digital number crunchers. But that doesn't mean that the digital machines
are better, or even "as good" as the simpler tools for many purposes.

Guess that's why telegraph keys are still around too, Hi.

Ron AC7AC

Oh... here's the URL's Sandy provided for those images:

http://asti.net/W5TVW/alliedLC1.JPG
http://asti.net/W5TVW/alliedLC2.JPG
http://asti.net/W5TVW/alliedLC3.JPG
http://asti.net/W5TVW/alliedLC4.JPG

http://asti.net/W5TVW/shure1.JPG
http://asti.net/W5TVW/shure2.JPG
http://asti.net/W5TVW/shure3.JPG
http://asti.net/W5TVW/shure4.JPG

http://asti.net/W5TVW/readme.txt

=======================================================================
At 05:29 PM 4/21/02 -0400, Tom Reid wrote:
>I got mine from the ARRL a long time ago
>----- Original Message -----
>From: Tom Bates <[email protected]>
>To: <[email protected]>
>Sent: Friday, April 19, 2002 5:50 PM
>Subject: [Antennas] L & C Calculator
>
>
>> Greetings...
>>    Anyone know where I can find one of those old cardboard slide rule
>calculator
>> gadgets which was used to find L, C, or Res Freq when 2 of the 3 variables
>were
>> known ?  I think Allied used to sell them years ago.
>>    Thanks es 73,   Tom   AA1NZ
>>
>> - - -
>>
>> Your moderator for this list is:
>> Larry Wilson KE1HZ [email protected]
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>
>- - - 
>
>Your moderator for this list is:
>Larry Wilson KE1HZ [email protected]
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