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Re: Making a Q-meter /


 

Added to:
New T50-2 36T measurement is a V-Meter Bandwidth Q measurement and a
SimSmith model demonstrating Injection Transformer fixture loss when
driven with 50ohm generator. Note V-Meter voltage ratio measured Q=205,
BW Q=207. SimSmith model suggests DUT with Q=207 will result with
voltage ratio Q=204.

John KN5L

On 9/20/22 3:39 PM, John KN5L wrote:
Evaluating frequency range can be performed by removing DUT from
Injection Transformer fixture, adding a wire between input and output of
Injection Transformer fixture and evaluate output of RF voltmeter.
FT50-43 50 turn, fixture with prototype RF voltmeter as shown, 1dB
bandwidth is 7kHz to 14MHz.

John KN5L

On 9/20/22 10:39 AM, John KN5L wrote:
Success! Some emails ago Jacques mentioned using a capacitor divider at
RF voltmeter input. It may be a requirement!



is updated with new RF voltmeter schematic and Q measurement results. RF
voltmeter input coupling capacitor is 10pF with a 120pF shunt added to
FET Gate.

RF Voltmeter calibrated using DG1032. Rather flat from below 100kHz to
10MHz, with 1dB down at 10MHz.

Demonstrating direct reading Q meter with Q=250 at full scale. Measured
DUT is well within range for the device.

John KN5L

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