Wish someone will assist

Measuring the Q.. Xl/r . Also, the nanoVna has Q function

But my coils all give low Q.. Less than 70 and can not understand why.. The coils are from kitsandparts

Have used wire gauge 24 and 26.. still can't get high Q at 7Mhz...not even high from 1Mhz to daylight

What can do?

Thanks

 

hi Z,
What is the measured inductance and resistance of the coils.?
E

 

hi Z,
What is the measured inductance and resistance of the coils.?
E

Hi E...
Inductance is 2.13uH and resistance is 2.6 ohms... 7.02Mhz

Frustrating

Thanks

 

Hello,

What type of core material do you use?

Bertus

 

Hello,

What type of core material do you use?

Bertus

Used T68 -2 and -6

Also have a table for the Al values

 

Along with the useful information posted above, for the highest possible use many small diameter separately insulated wires in parallel instead of solid wire. This reduces the eddy current losses within the copper.

 

hi Z,
Please post your actual calculations, your numbers look incorrect.?
E
Also what is the inductors internal capacitance.?

 

Hello,

In the posted PDF, the Q of the T68-2 is given on page 14 in the lower graph.
On page 16 the Q of the T68-6 is given.

Bertus

 

hi,
From the T68-2 it appears that the core is not the best choice for 7MHz operation.??

E

 

hi Z,
Please post your actual calculations, your numbers look incorrect.?
E
Also what is the inductors internal capacitance.?

The calculation is right E..The nanoVna also has a Q function.

Didn't check the capacitance... now, will use the graph to check things out

Although i know someone that had a Q of about 160 using T68-6 at 14 Mhz... Mine didn't work

 

If you were able to double the frequency without changing anything you would also double your Q, except we know that there is more than just resistance and inductance at work here.

 

If you were able to double the frequency without changing anything you would also double your Q, except we know that there is more than just resistance and inductance at work here.

lol...oh really? the resistance also increases with frequency but at a slower rate

The nanoVna also has a Q function.. Same reading with calculation Xl/r

 

hi Z,
If you are measuring the inductors laid flat on that what appears to a copper clad PCB, which is used as a ground connection , try moving the inductor away from the copper surface, then retest.


E

 

hi Z,
If you are measuring the inductors laid flat on that what appears to a copper clad PCB, which is used as a ground connection , try moving the inductor away from the copper surface, then retest.


E

No...can't do that... I even tried without the copper clad..same thing

From the smith chart, it has no capacitance

T68- 6...even from 1Mhz to 10Mhz... The Q is not above 75

Someone please solve problem for TS please

Thanks
but i think, problem lies in your response on ground

 

hi Z,
Do you have a inductor of a known Q factor so that you can check the NanVNA unit for accuracy.?

E

 

Have you calibrated the Nanovna with a similar testing layout, with open, short and 50 ohm load at 7 MHz?