开云体育

Thanks Tom, Any idea what it would be at a MHz or 10? I might set it up tomorrow and measure it at RF, but, if it's less then an ohm, I'm not sure how I would do that. :-) Mikek

Hi Mikek, Selecting Zo is an implementation choice. I picked 50ohm as all of my bench patch cables are 50ohm. Added to: https://www.kn5l.net/Q-Meter/ is "SimSmith Example" which demonstrates

It’s milliohms at dc. Take the resistance seen to the left of Q1’s base and divide by the product of betas. If dc betas are 100 each, you get about 5 milliohms, again at dc. Tom Sent from my

Yes, I keep confusing the 260A circuit driving the 0.02Ω and the HP 4342A not. Mikek

I'm not sure I agree, the schematic I posted shows a 75Ω resistor across the transformer as Zo. And I'm waiting for an analysis of the impedance converter amp to see if we can find it's output

The operating impedance for this example is 75 ohm. 75 Ohm R1 in tuning capacitor ass'y is matching load for impedance converter. The secondary of T1 has little to no change in load to the impedance

Someone sent me a private messaged and corrected me on the output impedance of the 50 to 1 transformer, it is 0.001Ω or 1 milliΩ. So, impedance ratio of 2500 x -.001 = 2.5Ω primary impedance. I'm

Hi Mikek, Added to: https://www.kn5l.net/Q-Meter/ is example HP-400E application. John KN5L

Hi Mikek, In the figure, Zo is output impedance of the oscillator, normally 50 ohms. The Zo resistor is the impedance match for the oscillator. The "Injection Transformer" supplies 1/50 of the voltage

John, now that I have thought about your graph a little bit, it seems clear the primary needs more inductance. To be flat down to 200kHz, I 'think' it would need about 160uh. That would be 168 turns

Here's two Q measurement methods, using S11 and S21 bandwidth. Measuring a reference Micrometals device for comparison. https://www.kn5l.net/Q-Meter/MM-T80-2-36T/ John KN5L

Hello George, You could have said the same about the bible – and I would have just deleted – or I might have said “Merely another assertion”. As soon as anyone tells me that something or

Oops, I really should remember to read all my incoming emails to see where the topic is going before making comments Johm

30 ga wire is 0.01" diameter. Your inductance is correct, 26.7 nH. I've handled LOTS of 30 ga wire :) John

Hi Brian, It has formulas to calculate inductance for every conceivable shape and size conductor and type of coil. Cheers, George G Sent: Friday, 16 September 2022 12:03 PM To:

The 0.02 ohm resistor is in series with the Inductor being measures so affects the Q measurement. I don't understand why the inductance of the thermocouple is meaningful, considering it's in series

I'm sorry, I got the numbers messed up. Corrected below. How does inductance change from say, a 1" long 0.10" diameter wire (30 Gauge wire) vs a 1" x 1"? square 1.4mil thick? (1oz copper pcb) Found a

The 0.02 ohm resistor is in series with the Inductor being measures so affects the Q measurement. I don't understand why the inductance of the thermocouple is meaningful, considering it's in series

And is that the inductance from one side of the square to the other, a 0.30" length, or from one end o the other, a 1" length. John

A comparison to a 1" long square wire 0.3" x 0.3" would be a more equivalent comparison. John