¿ªÔÆÌåÓý

  1. Test-Equipment-Design-Construction
  2. Messages
Single Messages Topics Expanded Polls

Re: Making a Q-meter /

 

I¡¯m reading your observations about high Q measurements and calculations . This is very interesting. High Q is vey dif¨ªcilt to measure. Q-meters was designed as a practical instrument to design inductors mainly and also capacitors . On inductors Q are very important but also self resonance frequency. In radio practice when the components gets connected with tubes or transistors que Q goes down very much . For this reason I believe that HP q-meter specs are more than enough for practical proposes. 10% for Q cose to 1000 it¡¯s very good !!

On 20 Nov 2022, at 19:29, John KN5L <john@...> wrote:

?On 11/20/22 5:49 PM, Mikek wrote:
So, what I think we have is loss resistance (from the self capacitance)
of 9,848,000¦¸
9,848,000¦¸ is Rp for the capacitive component of the added 11M resistor.

It was much easier for me to understand by viewing the SimSmith model
(attached again), where the capacitive component is isolated with C1
with C=CpC and Q=CpQ, with values of 400fF and 45.

One can discuss if the Q should be for the capacitive component or for
the resistor in total.

Both of our answers are equivalent. 45 for the capacitive component and
22 for the total resistor.

John KN5L




image.png
ss-Qmeter-AA7U.png

Join [email protected] to automatically receive all group messages.