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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I just picked up two of these cheap. 3440aa output of resistor network is selected for each of the ranges by the eight position FET Switch U8. Showing results 1 – 9 of 9 products found.
Millivoltmeters – All Manufacturers –
Two principal techniques have been employed to deal with the low level and transition region response characteristics: And reliably, the probes were separated from them when the item went to surplus sale, or stolen first. Table 1 above includes a truth table for FET switch U8.
Before I got these I was going to make an RF detector probe from one of the simple plans you see all over the internet. Aug Tue 23, 1: But they were hand-tweaked instruments with hand-selected components, and they had to give you another probe or two for use at higher voltage levels!
The probes are usually much more complicated than that. Replacement probes for all the Ballantine, Booonton, Millivac, Helper and other RF voltmeters which always show up without them You won’t be able to get the engineering and parts required for the bandwidth.
Ballantine RF Millivoltmeter 3440A With Accessory Kit
The first four steps, for the 1 to 30 mV ranges, are connected together through resistor R59 to provide the inverse of square law hallantine. Any users here of this instrument? Search Expert Search Quick Search.
More like hundreds of millivolts at best. The two pole, four position switch U14 is controlled by two logic signals A and B from the range control Preamplification at first appears to be the ideal solution.
Untested with no probes. The precision resistor network comprising resistors R52, RR63, plus the feedback network of meter amplifier U9, performs the required scale linearization.
Common calibration errors are eliminated through temperature compensation of the probe detector diodes; double shielding protects the interchangeable mllivoltmeter from nallantine handling and pickup. In the 3 mV range, the reference is reduced by a voltage divider comprising resistors R82, R83, R84 and R86, to correspond to the reduction in gain of the preamplifier Ballantine A RF millivoltmeter Posted: For example, the shaping amplifier in the Boonton Model No.
Annoying to say the least This instrument has a 4 digit mlllivoltmeter with high precision, small frequency effected errors and high input impedance. The apparatus of claim 3 wherein the range control comprises a gallantine range switch, a plurality of data line amplifiers, each having an input connected to a portion of the range switch and each driving a data line, a first electrically controllable switch responsive to signals on a plurality of data lines for adjusting the gain of the input amplifier, and a second electrically controllable switch ballajtine to signals or a plurality of data lines for adjusting the resistances of the resistance network.
I’m sure there are other good solutions out there as well. In a typical RF millivoltmeter made in accordance with my invention, the detector probe output is simply amplified sufficiently to place the detected signal in a predetermined amplitude range.
Thanks for all the information, these definitely were gov’t, there is a USMC callibration on one of them. I millivlotmeter RF probe and found lots of information about making a probe for use with a vom or dmm bqllantine the 1n34 diode. All switches are touch switches with high quality, providing good hand feeling and high reliability. Gain is set at approximately -1 resistors R64 and R66 in conjunction with the resistor network Thermal effects, input offset voltages and currents which would affect the meter’s zero point are balanced out by biasing the inputs of U1 and U2.
Although some of the figures include typical component values, this disclosure is not limited to the values shown. Probes are usually bad because users like to measure the signal from their kilowatt linear with the 344a. A root-mean-square rms response in the small signal region below 30 mv may be obtained by taking the square root of the sum of the squared signal components.
Table 1 shows the connections established by the FET switch U3 in response to millivoltmster signals on its input terminals 6, 10 and The apparatus of claim 6 wherein the diode detector is a pair of germanium point contact diodes in a series configuration. In the embodiments of FIGS. Temperature variations will change the detection efficiency and conduction offset so as to affect calibration.
The other thing is that I seem to recall that the probes are serial number matched rd the instrument. Is the probe proprietory or can I make a probe?
High rms accuracy, traceable to NIST, is assured regardless of waveshape. The identification of specific components, component values and circuit details in this specification are for illustrative purposes only.
Adjustable resistance Rg is used to adjust the gain of amplifier A 3 so that its output voltage V 3 is determined by the formula EQU3. 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 generally more restricted than that of the detectors and also because range switching at high frequencies would be impractical to implement at low cost.
The apparatus of any of claims 1 through 4 wherein the diode detector is a germanium point contact diode. The ambient temperature inside the probe is sensed by diode CR3 and the base-emitter diode of transistor Q1. Resistor R72 adjusts full scale calibration of the indicating meter. 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.