It’s the “no probes” part that’s the killer here. The probes are what gives the meter its bandwidth. Probes are usually bad because users like to measure the signal. Schematic of Boonton Model 92 A RF Millivoltmeter; Boonton Electronics Corp. . In the Ballantine Model A RF millivoltmeter, which is. The old Boonton RF Millivoltmeter or Boonton RF Microwattmeter or . Ballantine Labs A Standard RF Probe – 10KHz to GHz with pf.
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Probes are usually bad because users like to measure the signal from their kilowatt linear with the things. This portion of the circuit is shown in FIG.
When the millivoltmeter is used on the 1 mV range, additional damping and low frequency noise filtering is provided by the circuit including capacities C16 and Although some of the figures include typical component values, this disclosure is not limited to the values ballangine. I forgot my password. Okay I don’t feel bad.
AD is used to precisely follow a square root response with the transfer function. Is the probe proprietory or tf I make a probe?
The apparatus of claim 5 wherein the gain switching between the lower ranges is accomplished by changing the feedback of a ballantime amplification stage and the gain switching between the upper ranges is accomplished by changing the feedback in a subsequent amplification stage.
You won’t be able to get the engineering and parts required for the bandwidth.
Aug Thu 25, 5: Some of the old Millivac RF voltmeters MV series, for examplecould get down to the single millivolt range with nothing more than crystal detector probes. Since this transition region is often an important region for voltage measurement, as are the regions above and below, it is necessary to avoid or compensate for the transition response characteristic as well as to provide the appropriate response in the square law and linear regions.
Relative gain or loss measurements are simplified by a 0 dB reference adjustment. Aug Thu 25, 3: The voltmeter of any of claims 2, 3 or 4 wherein the adjustable gain input 4340a comprises a preamplifier stage having a pair of preamplifiers connected in an instrumentation amplifier configuration to receive differential outputs from a pair of diode detectors and a millivolgmeter amplifier connected to receive the output of the preamplifier stage.
The square root converter U6 provides the proper linearization and calibration for the 1 mV through 30 mV Ranges. In the 10 mV range, a further reduction is provided by substituting resistors R85 and R87 for resistors R84 and R86 in the voltage divider.
A RF Millivoltmeter | Ballantine – TechRecovery, LLC
Buffer amplifier circuitalso shown in FIG. The output DC voltage at leads and is a function of the amplitude of the input signal on lead I’m sure there are other good solutions out there as well. Potentiometer R68 can be used to adjust the recorder output for one volt full scale open circuit or to normalize the output to the recorder being driven.
An eight-position range control switch S2, shown in FIG. The apparatus of any of claims 1 through 4 wherein the diode detector is a pair of germanium point contact diodes in a series configuration. Only goes down to mV, though. The Ballantine A still appears to be a current instrument, and a rather nice one.
Millivoltmeters – All Manufacturers –
For a typical RF diode detector of the type used in RF millivoltmeters, a square law response or transfer function is obtained for signals below approximately 30 millivolts mVa linear response or transfer function is obtained above approximately mV, and the response between approximately 30 and mV is in transition between square law and linear. I have seen pallets of millivoltmeher meters at surplus sales, all wrapped in plastic, without a single probe in the bunch.
Two principal millivoltmetr have been employed to deal with the low level and transition region response characteristics: Ballzntine measuring range switching makes your usage more convenient. Users browsing this forum: The precision resistor network comprising resistors R52, RR63, plus the feedback network of meter amplifier U9, performs the required scale linearization.
3440A RF Millivoltmeter | Ballantine
Transistor Q2 is a grounded emitter power amplifier which is used to vary the collector voltage of Q1. My Boonton’s use special diodes in the probe for full-wave rectification, which is then converted back to AC in the instrument via a mechanical chopper. A SumoBrain Solutions Company.
The output of the detector diodes, however, is a non-linear function of signal amplitude. Google [Bot]Prutser and 7 guests. Several types of such detection circuits are known.
There was a QEX magazine article a while back about building a compensated RF voltmeter using a pair of matched diodes and some high-impedance opamps, if you want to homebrew something.