How can I measure the rotational force needed to adjust a vacuum variable capacitor?

Answered
0
0

I just ordered a vacuum variable capacitor to continue my experiments with loop antennas. This one is decent quality, U.S. made, used capacitor. I was wondering if there was a relatively simple, yet reliable, way to measure the rotational force needed to tune the capacitor. Part of my goal is to design a coupling that slips when the motor drives the capacitor to its limit.

General questions mechanical coupling   loop antenna   variable capacitor
Share
  • Jim
    • Jim
    • 7 months ago
    Thanks for this question Andy. Considering you are somewhere near the top of our Elmer pecking order, I’d be curious to see who can answer this one. If my dad were alive, he probably could; he’s not. If someone answers this one to your satisfaction, dinner is on me (seriously)!
  • Jim
    • Jim
    • 7 months ago
    Andy, I’m curious what’s wrong with ChatGPT’s answer to this challenge. I inserted your question as a prompt and read it and it seems reasonable. Thoughts?
  • wa3ltj
    I entered my question into chatGPT. It wants me to use a torque wrench or torque screwdriver, which I don’t have. It recommends a flexible coupling. Bad idea for measuring a torque.I will 3D print an arm to go on the shaft. It will have a notch at a measured distance from the center of the shaft. At the notch, I will hang a small bag. I will put pennies into the bag until the shaft rotates.This was the recommendation from a PhD mechanical engineer who is a ham.
  • Jim
    • Jim
    • 7 months ago
    Roger that. Note that if you do need a torque wrench, I have two of different ranges.
  • You must to post comments
Filter
Sort by: Oldest First
Great Answer
0
0

Response given by the OP himself: “I will 3D print an arm to go on the shaft. It will have a notch at a measured distance from the center of the shaft. At the notch, I will hang a small bag. I will put pennies into the bag until the shaft rotates. This was the recommendation from a PhD mechanical engineer who is a ham.”

Expertise level
Elmer
References and sources
Recommendation provided by a PhD mechanical engineer who is also an amateur radio operator.
  • You must to post comments
0
0

I 3D printed a calibrated, counterweighted arm. I hung a plastic bag and filled it with quarters until the shaft of the vacuum capacitor reliably moved. At 40 quarters the arm rotates reliably. The bag was hung 10 cm from the center of the shaft. I tried to upload a photograph but the system would not allow me to upload a picture. (Note to moderator: Are we supposed to be able to upload a picture?)

40 quarters at 10 cm.
A US quarter weighs 5.670 g
40 * 5.670 = 226.8 g
At 10 cm, that is 2268 g-cm = 2.268 kg-cm
The torque motors I am looking at are measured in N-m
2.268 kg-cm = 0.222 N-m minimum torque

QED

 

 

Expertise level
Elmer
  • You must to post comments
Showing 2 results
Your Answer

Please first to submit.

Report

Contains abusive or derogatory content
Bias is a tendency to favor or lean towards one perspective, person, or group, often at the expense of another. Bias can be conscious or unconscious (implicit) and can influence judgment, decision-making, and behavior. Unlike prejudice, which is explicitly about preconceived notions, biases can be more subtle and can even occur without the individual being fully aware of them. Bias is broader and can be positive or negative, affecting various aspects of life like decision-making in work, preferences in social settings, etc. Bias is basically a difference of opinion and that must be respected.Prejudice, however, refers to negative, preconceived opinions or attitudes held by an individual or group towards another group or individual, often without factual basis or experience. Prejudices are usually harmful, leading to unfair treatment or discrimination. They are often based on stereotypes and can be about race, gender, religion, nationality, or any other distinguishing characteristic. Prejudice is more about feelings and attitudes. Ham Community does not tolerate prejudice. We are all different, that's fine.Remember, duty and honor are built on respect.Use this reporting category sparingly and only if you are quite certain that the member is being openly and hurtfully prejudiced.
This member displays harrassing or bullying behavior
Contains mature or sensitive content
Member is aggressive or insulting to others
Member believes this content possibly contains misleading or false information
Member is not inappropriate or ill-meaning but consistently provides poor or misleading advice.
This content seems to advertise or promote products or services without explicitly saying so or seemingly having obtained permission from site administrators.
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .