Browse Groups

• ## Resonant Frequency and the Slide Rule...

(1)
• NextPrevious
• This is an operation i do quite a bit, homebrewing regenerative receivers. Here is my method: to find the tuning range for a 30-365 picofarad capacitor and a
Message 1 of 1 , Jan 7, 2004
View Source
This is an operation i do quite a bit, homebrewing regenerative

Here is my method:
to find the tuning range for a 30-365 picofarad capacitor and a 240
microhenry inductor.

Let me do it two ways, one for use on a slide rule with a mannheim
layout, one for a Doric arrangement. (on the mannheim, i often make a
gauge mark at 2Pi on the CI scale... then it all works out like the
doric arrangement.)

Lets find the low frequency range on the mannheim.

Set left A index to 240, set cursor at 365 on B. Because this is 3+3
digits (even) use the leftmost pair. (roughly 8.78) (See note).
Line up the 2 on the CI scale on the cursor, and then move the cursor
to the PI on the C scale. (*2 *pi) (Roughly 1.86)
Index on C, read resonant frequency on C opposite index on D. Answer
is 537 KHz.

Note: This is easier if you have a gauge mark at 2PI on CI or have a
CIF scale. Simply line up the 2PI (2 on CIF) with the answer from
step 1, and read the resonant frequency off at the D index.

Thus:

High resonant frequency:

Left A index at 240, set cursor at 50. (this is 3+2 digits, so use
right hand pair)set cursor there (roughly 8.5 on D).

Line up the 2PI gauge mark or the 2 on CIF at the cursor, read 1.873
MHz on C above D index.

This does not work nearly as well on my N4 with no A-B scales, i wind
up having to read the root and placing it on the C-D scales.

Regards,

Ed
Your message has been successfully submitted and would be delivered to recipients shortly.
• Changes have not been saved
Press OK to abandon changes or Cancel to continue editing
• Your browser is not supported
Kindly note that Groups does not support 7.0 or earlier versions of Internet Explorer. We recommend upgrading to the latest Internet Explorer, Google Chrome, or Firefox. If you are using IE 9 or later, make sure you turn off Compatibility View.