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In about the middle of this page, I see a bootstrapped tube. http://www.valvewizard.co.uk/accf.html It looks easy, but, does it change gain, or frequency response? Mikek

Next step is to measure the measurement. A method is plotting many measurements and ensure plot shape is appropriate. Added to: https://www.kn5l.net/Q-Meter/ is a Q-Curve of a T50-2 36T #24 DUT. Looks

Interesting question and beyond my skill level. I may ask that on an electronic design group and see if they have an answer. In the end though, I would much prefer to start solid state replacement

I wonder if the 260 voltmeter circuit could be bootstrapped by lifting the 100M resistor from ground, adding another resistor to ground, and adding a cap from the junction to the636A cathode? John

A Q Capacitor prototype is added to: https://www.kn5l.net/Q-Meter/ A rotor shaft ground wire is required. This old vintage capacitor was too scratchy. Measurements are repeatable. Q of variable

I remember a maxim, "when you measure something, you change it". It is officially called the "Observer affect" from the wiki, regarding electronics, (I think it is incomplete and needs more work) "In

I was thinking the capacitive divider was to reduce the C loading of the voltmeter on the resonant circuit, but it's to reduce the input resistance. Wouldn't matter if you are measuring 20 ?H coils,

That's exactly how I used the Kleijer amp, driving my Oscilloscope and doing 3db BW measurements. Mikek

An oscilloscope can be used as a RF Voltmeter when using a fixture with capacitive divider. https://www.kn5l.net/Q-Meter/ Added to section "Injection Transformer, With Capacitive Divider, Fixture" is

here: https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1970-09.pdf 10/120 pF divider work well.<<< Yes and nothing wrong with using a capacitive divider, I'm just adding, there are high input impedance

A capacitive divider seems to be a requirement. Additional information here: https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1970-09.pdf 10/120 pF divider work well. "To RF Vmeter" is connected to

You have a label, "To RF Vmeter" at the output of your capacitive divider, is that the HP410E or your RF Voltmeter Prototype? I'm looking for caps to make the divider/vmeter and connect it to my

Yes, I saw it, I'm just adding that in can be better, as in 0.25pf and 100MΩ input impedance. Yours adds 9.3pf to the tuning capacitor, (should use high Q caps) and I have no clue what the parallel

Hi Mikek Schematic of functional RF Volt Meter: https://www.kn5l.net/Q-Meter/ First Section with Title: "RF Voltmeter Prototype" this version has 10/120 pF divider in the schematic. John KN5L

OK, so you are unloading the resonant LC improving (getting closer to) the actual Q. I thought you were making some improvement to the injection transformer. Be aware the HP 400E has, as the manual

Mikek, Here is a graph showing the output impedance magnitude vs frequency for various transistors, including the 2N5109. The last two are microwave transistors and they provide the most constant

Hi Mikek, https://www.kn5l.net/Q-Meter/ Section "Injection Transformer, With Capacitive Divider, Fixture" John KN5L

I need a rough schematic, are saying both a 50 to 1 transformer and a capacitive divider? Thanks Mikek

Hi Mikek and David, HP 4342A a single 50:1 turn ratio toroid with a range of 22kHz to 70MHz. The simplest way to make a Q meter is a 50:1 Injection Transformer with capacitor divider Fixture and use

Hi David, Have you any more thoughts on the above conundrum? The only solution I see is to have two or three transformers to cover the frequency range. Mikek