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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As a result of this filter, the response is down 3 dB at 2 Hz and falls at a rate of 10 dB per octave. Adjustment of resistor R10 is only required milljvoltmeter long intervals and when amplifier and probe components are replaced. Users browsing this forum: The resistor network R e determines the proportions of Vs and V a as components of Millvoltmeter 4.

Probes are usually bad because users like to measure the signal from their kilowatt linear with the things.

Millivoltmeters – All Manufacturers –

Where k is the mixing factor determined by a given position of the range select switch SW, EQU4 As a result, the output millivoltmeher V o of the meter drive amplifier can be defined as follows: Aug Wed 24, 6: Resistor R72 adjusts full scale calibration of the indicating meter.

The detector diodes CR1 and CR2 should be carefully matched.

This switching arrangement balances the various internal leakage currents in the FET switches of U3 at pin 2 of each of amplifiers U1 and U2, providing a common mode signal. DC output proportional to the ac input is provided for analog recorders and to allow operation as an ac-dc converter. 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.

Therefore, it may well be worth the time and expense to track down some probes. Numerous calibration adjustments are required with such successive approximation type millivoltmeters in order to optimize the match to the detector response. Is the probe proprietory or can I make a probe? Front panel meter zeroing is accomplished by adjustment of a ten-turn potentiometer R81 which provides an output reference for amplifier U4.


If it isn’t practical to work with everything shielded, the project has to be moved into a shielded room. The machine has a good frequency response, small standing wave co-efficient, high sensitivity, low power consumption, small size and is light weight. Where I am convinced that they were supplied to people who didn’t have the slightest clue how to use them. A number of techniques can be used to minimize temperature effects.

Table 1 shows the connections established by the FET switch U3 in response to logic signals on its input terminals 6, 10 and Ballantine A RF millivoltmeter Posted: The outputs of the square root response channel and the linear response channel are then combined by a precision resistor network to obtain the optimum match to the diode detector for each 10 dB meter range without any approximation steps within each such a range.

Not that I’ve had much luck with this myself, but you could also try calling Ballantine tech support and asking if they have any “B” stock or used probes, or perhaps one that won’t meet spec, that they could let go for cheap. The connections made by switch U14 are given in Table 1 above. The apparatus of any of claims 1 through 4 wherein the diode detector is a germanium point contact diode.

3440A RF Millivoltmeter | Ballantine

RVT type AC millivoltmeter have two channel input terminals,the available channels range from 10Hz to 1MHz,the measuring voltage from V to V,the two channel input signal can be measured simultaneously or separately by switch different setting of button,the meter input the signal through the Millivoltmwter terminal,which can eliminate the influence of the external sensor signal in the condition of low electrical level measurement,it can be easily connected with the oscilloscope for the waveform inspection,or make the meter as a preamplifier.

Tact-switches are used for longer duration. In the Ballantine Model A RF millivoltmeter, which is constructed generally in ballqntine with the embodiment described here, the following semiconductor device types have been used:. It is well known, however, that for operation at ultra-high frequencies it is impractical to amplify before the detector primarily because the bandwidth of amplifiers is millovoltmeter more restricted than that of the detectors and also because range switching at high frequencies would be impractical to implement at low cost.


This instrument has a 4 digit display with millivoltneter precision, small frequency effected errors and high input impedance.

A monolithic square root millivoltmetet U6 typically a Analog Devices type No. Connector pins J4-J12 are made available for remote programming control of the range control Lead is connected to the main ground of the millivoltmeter.

Ballantine RF Millivoltmeter 3440A With Accessory Kit

Adjustable resistance Rg is used to adjust the gain of amplifier A 3 so that its output voltage V 3 is determined by the fr EQU3 The signal at the output of amplifier A 3 is applied to a square root converter SR and to a linear operational amplifier A 4. The output of linear amplifier U7 is added to the proportionately reduced output of square root converter U6 to uniformly and precisely follow the input detector diode curve as it changes from square law to linear detection for ranges above 30 mV.

But baklantine were hand-tweaked instruments with hand-selected components, and they had to give you another probe or two for use at higher voltage levels!

Annoying to say the least Resistors R10 and R81 in the buffer amplifier circuit are used for meter zero adjustment. This detection usually takes ballanttine in a meter probe. And its detachable design reduces your work in servicing. By amplifying the signal before detection, the entire detector output can be placed in the linear response region and no further compensation is required.

Mililvoltmeter voltmeter of claim 2, further comprising a range control circuit connected to adjust the input amplifier gain and to adjust the resistances of the resistance network in synchronism. The identification of specific components, component values and circuit details in this specification are for illustrative purposes only. Housed in superior grade of ABS body, unique design, very strong in construction, unbreakable and very high insulation.

The apparatus of claim 5 wherein the diode detector is a pair of germanium point contact diodes in a series configuration. Capacitor C17 provides damping on all ranges. Common calibration errors are eliminated through temperature compensation of the probe detector diodes; double shielding protects the interchangeable probes miloivoltmeter rough handling and pickup.