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1. HIFIELD VLF RECEIVER FREE TO EXPERIMENT
2. HIFIELD VLF RECEIVER FULL SIGNAL STRENGTH
3. HIFIELD VLF RECEIVER MOVIE OF COMPLETED

The polar response of the completed receiver was plotted with the equipment mounted on a large protractor as shown below. The final VLF receiver for SIDs. The end connector is a 9 Way D Type. The outer plastic cover is 40mm diameter.

Hifield Vlf Receiver Movie Of Completed

We will move it to a permanent box with soldered connections. This is how we built it at first for testing. Hickok Hieronymus Highfield Hilbert Hillary Hillcrest Hillel Hillsboro Hillsdale.View 1 minute movie of completed receiver, working and receiving WWVB 60 KHz time signal station.It works even when built like this on a solderless breadboard. Antedating antelope antelopes antelopes antenna antennas antennae.

Hifield Vlf Receiver Full Signal Strength

More will be added as work progresses. A sudden drop in recorded signal strength at night indicates you may have recoreded an astronomical event.This receiver is a work in progress. At night this effect dissipates and WWVB comes up to full signal strength.Monitoring WWVB's signal strength can allow detection of solar flares, x-ray bursts, gamma ray bursts, or other space events that greatly disturb the ionosphere, causing a sudden drop or increase in signal strength.You can also watch WWVB fade out an hour before local sunrise, and signal level increases at night an hour after sunset each day.

See diagram and photos.Note L2: 12 turns works well from 10 KHz - 300 KHz with FE part.L3 = 1 turn # 22 wire wound on FE. 5 turns gives less selectivity.NOTE: In our receiver we changed L1 to 2 turns on 06-26-2015, giving much better selectivity performance.L2 = 12 turns # 22 copper magnet wire wound on FE. 2 turns gives narrow selectivity. 3 turns gives even more selectivity. 4 turns gives good selectivity. See diagram and photos.NOTE L1: Selectivity is the ability of the receiver to separate stations on the dial.

Hifield Vlf Receiver Free To Experiment

Wire in as shown in the diagram and photos.VC1 = 15 pF - 384 pF variable capacitor. See photos.NOTE: Do not omit RFC1, it provides the needed signal blocking to force the received signals into the Q2 audio detector stage. Don't overdrive it, you'll loose headroom on signal strength measurements, but feel free to experiment, depending on your needs.RFC1 = 144 turns # 28 wire wound on separate FE core.

Be sure to use fresh or fully charged batteries during this calibration. The correct adjustment is the following for highest signal sensitivity: The meter should just barely indicate (it should move about the width of meter's pointer) above 0 when power is turned ON with nothing connected to the receiver. NOTE: You may want to use a 50 K trimmer resistor for precise adjustment of the signal meter. Omit this part if quick meter response is desired.C8 = 500 pF mica capacitor or other high Q type low loss capacitor.R8 = 33 K-ohms.

Make sure that the strongest signals will give a slightly past full scale reading for best performance. Adjust it to meet your research needs. Adjust this value so meter will not slam off scale on strongest signals. Exact value depends on your meter's sensitivity. Some VLF signals increase greatly at night so you may need to adjust your meter level to match your research needs based on this fact.R9 = 50 ohms to 200 ohms. However, if you want less meter sensitivity on your receiver you can adjust R8 to match your exact requirement.

BFO drive levels of 0.1 volt to 1.5 volt are input to the BFO jack. This resistor keeps the BFO drive level to a low managable value, and increases dynamic range when operating in BFO mode. We will be using rechargeable batteries so these have a slightly less voltage than standard AA batteries, so we did all testing with them.R10 = 47 K-ohms.

NiMH batteries will read lower on the meter by 0.5 volt.NOTE: SW1: use this switch for output level calibration when recording to a chart recorder. Set meter reading to 100 percent with new fresh batteries at a total of 3 volts, if only for calibration. High resistor value allows DC thru but blocks any RFI that might come from connected recording equipment.R13 = approximately 500 ohms, for battery test meter function, but exact value will be based on your meter.SW1 = momentary pushbutton switch for battery test function. High resistor value allows DC thru but blocks any RFI that might come from connected recording equipment.R12 = 100 K-ohms.

If the meter has a coil resistance greater than 200 ohms, place a resistor across the meter terminals to make the total resistance 200 ohms. You can use the meter movement from an analog volt meter also, it does not have to be the same one shown here. Meter shown has a 120 ohm coil movement. (not shown in diagram).METER: Mouser part number or any meter having a 120 ohm to 200 ohm coil movement.

Great for back-lighting the meter at 3 volts DC.AA-cell Plastic Battery Holder: Hillman brand from Lowes Hardware Stores. Hillman brand part number 881510, from Lowes Hardware Stores. Make sure your selected meter does NOT have a built in diode bridge.Panel Meters of all kinds can be found at this linkLamp: 6 volt hobby filament lamp. Do NOT use this part in the signal meter circuit. R9 makes up for the difference if the meter is lower value than 200 ohms.Important note: Some VU meter's come supplied with an external diode bridge that can be connected to the meter to allow readings of audio levels.

Reduce BFO input drive to about 0.1 volt input or until meter reads 75 percent of scale when doing scientific research (leaves some headroom for signals to increase further). The signal meter should swing past full scale when WWVB is coming in strong at night. This will produce a beat note of 400 Hz from the speaker when WWVB is tuned in. The receiver will also drive line-level jack of an audio amplifier.You can also use a pair of mono headphones or an earphone directly from the receiver's output jack, though not too loud, the WWVB signal is hearable in headphones with no extra amplification.From any sinewave signal generator, feed in a sine wave of 0.3 volts rms to the BFO input at 59.60 KHz. It will operate down to 1.5 volt so it works great with rechargable NiMH batteries which are typically 1.25 volt each for a total of 2.5 volts.The receiver will also work on just one 1.5 volt battery, however the signal meter function requires that the battery voltage be above 2 volts.Connect an audio amplifier having a 5000 ohm microphone input impedance at 1 mV sensitivity, for very loud reception. Holds two "AA" batteries.This receiver is designed to work work on 2 AA cell batteries of 1.5 volt each for a total of 3 volts.

In this photo the wood has not yet been painted and stenciled with the lettering. Other cases may be used also.The wood front panel piece is made of oak wood and is 9 and 15/16ths inches wide and 5 and 15/16ths inches high and 0.2 inch thick. C5 also prevents the BFO drive from entering the signal strength meter and causing meter to indicate a signal, when no input signal is present.A 'pelican' brand plastic case is being used for the receiver project. This value is set by C5 value of 1 uF. A BFO input of 60.4 KHz will also produce a beat note of 400 Hz, but it is much weaker than when a frequency of 59.50 KHz is used as the BFO input.The receiver has a peak audio detector response between 150 Hz to 500 Hz, with the center being around 300 Hz.

The use a hack saw to gently cut down the vertical portions. Use as small a drill bit as you can find, and drill holes carefully along the inside of the lines you mark. The cut out of the meter hole was done by drilling out the part of the board along where the meter will be mounted. The size is 1:1 and it was taped onto the wood board and was drilled thru the marked points.

You can also use a jig saw to cut out the whole piece without needing to drill the 100 tiny holes along the lines.