HF crystal tester

Quick components tester
by sv3ora

This quick and dirty components tester will show you if a two-terminal component is good or faulty. It will not measure the component properties, it is an "on/off" device, component is either BAD or GOOD. Despite being very simple, it is cheap and portable and it performs some interesting tests on components, not just continuity testing. It can also be used to troubleshoot some faults in circuits. It is designed so that it requires no adjustments, so no special equipment is needed to calibrate it.

moment

short

blue

a23

10k

bf495

680

1nf

4n7

100

bc547c

100pf

1n34a

10nf

68uh

The schematic of the tester is shown above. Below is the Schematix data, if you want to send this tester schematic to your HAM radio friends through morse code (or any other mode).

atmoment bbit bctt bhit biei bjea bkea blea bmea bnea boea bpea bqei brea bsei btfe buii cashort cbae ccst cdse chae ciae cqrb crblue csiu cubr cva23 dbis dctt dg10k dhes diae dost dpse dqes dsae duee edit eeea efei egea ehhe eine ejbf495 eqsi eses et680 fdrb ffrb fg1nf fhse fiae fj4n7 fn4n7 fqes fr100 fsie ftea futt gbni gcst gdse gfer ghie gihe gjte gktt gmts gnte goei gpai gqhe grea gsne gtbc547c gust gviu gwed gxin hdsi hfsi hg100pf hhse hies hj1k hksi hmsi hn1n34a hohi hp1n34a hqse hr10nf hsae husi ideu ie68uh ifee ihee iiee ikis ilea imti ioee iqee isee iuee jdee

The tester can be used for the next purposes:

Test resistors for open (range is 0 ohms to 10Mohms max)
Test inductors for open
Test diodes for open or short and determine polarity
Test LEDs or IR diodes for open or short and determine polarity
Test high values of electrolytic capacitors, >0.47uF, for open or short and charging capability
Test medium values of electrolytic or non-electrolytic capacitors, 10nF to 1uF, for open or short and charging capability
Test low values of static or variable capacitors, 4.7pF to > 1uF, for short and operation as resonant elements in an actual HF oscillator
Test crystals from <1.84MHz to >33MHz with operation as resonant elements in an actual HF oscillator
Test ceramic resonators from <1.84MHz to >33MHz with operation as resonant elements in an actual HF oscillator
DC continuity tester, for finding broken connections in cables, PCB traces etc.
DC detector, detect if there is an external voltage or not.
HF RF signal injector and detector, for finding RF related faults that can't be found with DC continuity. The injector and detector operate simultaneously and independently, so they can be used for other purposes as well with the help of external circuits (eg. impedance bridge etc.).
Standalone general purpose RF detector, as the detector bandwidth alone is several hundred MHz
HF signal generator, as the oscillator operates from <1.84MHz to >33MHz using crystals or ceramic resonators.
Low voltage capacitor discharge tool (a simple short) useful prior to any capacitor testing and when you have no metal nearby to discharge a capacitor

The circuit is composed of an HF oscillator followed by a detector. There are several points in the schematic (A to G) where the different tests, mentioned above, can be performed. These tests are performed as shown below:

Place a resistor at point F. If the resistor is open, the indicator LED will be off. If the resistor is good (or shorted) the indicator LED will be on.
Place an inductor at point G. If the inductor is open, the indicator LED will be off. If the inductor is good (or shorted) the indicator LED will be on.
Place a diode at point G and note the indicator LED state. Reverse the diode polarity (connect it the other way round) and note the indicator LED state again. If the indicator LED is off on both diode polarities, the diode is open (bad). If the indicator LED is on, on both diode polarities, the diode is shorted (bad). In a good diode, the indicator LED will be on on one diode polarity and off on the other. That way you can determine the anode and the cathode of a good diode, if there are no markings on it.
Place a LED or IR diode at point G and note the indicator LED state. Reverse the LED/IR polarity (connect it the other way round) and note the indicator LED state again. If the indicator LED is off on both LED/IR polarities, the LED/IR is open (bad). If the indicator LED is on, on both LED/IR polarities, the LED/IR is shorted (bad). In a good LED/IR, the indicator LED will be on on one LED/IR polarity and off on the other. That way you can determine the anode and the cathode of a good LED/IR. A good LED will be also seen to light up along with the indicator LED, when it is in the right polarity in the circuit.
Place a high value of electrolytic capacitor (>0.47pF) at point G (with the correct capacitor polarity!) after you have previously discharged it, by shorting it's terminals with the help of point A. If the capacitor is shorted, the indicator LED will be on continuously. If the capacitor is open, the indicator LED will be off. In a good capacitor, the indicator LED will be initially on and then gradually switched to off, as the capacitor charges up. The time that it takes for the indicator LED to be completelly switched off, depends on the value of the capacitor. In very large capacitors, this time can be several seconds.
Place a medium value of electrolytic or non-electrolytic capacitor (10nF to 1uF) at point F (with the correct capacitor polarity if it is electrolytic!) after you have previously discharged it, by shorting it's terminals with the help of point A. If the capacitor is shorted, the indicator LED will be on continuously. If the capacitor is open, the indicator LED will be off. In a good capacitor, the indicator LED will be initially on and then gradually switched to off, as the capacitor charges up. The time that it takes for the indicator LED to be completelly switched off, depends on the value of the capacitor. In very small capacitors, you will see the indicator LED to light up instantly and then switch off.
Place a low value of non-electrolytic static or variable capacitor (1pF to >1uF) at point F, after you have previously discharged it, by shorting it's terminals with the help of point A. If the capacitor is shorted, the indicator LED will be on continuously.
Place a low value of non-electrolytic static or variable capacitor (>4.7pF) at point B, after you have previously discharged it, by shorting it's terminals with the help of point A. For this test, the D and E terminals must be shorted. If the capacitor is good, the indicator LED will be on. I have noticed that this works with greater value capacitors as well as electrolytic capacitors, but I am not sure if this is an indication of a good capacitor of this type.
Place a crystal or a ceramic resonator (<1.84MHz to >33MHz) at point C. For this test, the D and E terminals must be shorted. If the crystal or the ceramic resonator is good, the indicator LED will be on.
To use point G as a general purpose DC continuity tester, connect the ground to one side of circuit under test (cable, PCB trace etc.) and point G to the other. The indicator LED will be on on short and off on non-short.
To use point F as a general purpose DC detector, connect the ground to one side of circuit under test (eg. the ground of a power supply) and point F (100 ohm resistor side) to the DC source of the circuit under test. The indicator LED will be on if a voltage is detected.
To use the tester as an "RF continuity tester" (injector/detector), isolate points D and E. Connect point D to one side of circuit under test (RF input) and point E to the other (RF output). The ground must be connected at the circuit under test too. Then connect a crystal or ceramic resonator of the desired frequency to point C. The indicator LED will be on if RF can pass through the circuit under test and off if it cannot pass through.
To use the tester as a general purpose RF detector, isolate points D and E and connect point E to the circuit under test (eg. an RF oscillator). The ground must be connected at the circuit under test too. The indicator LED will be on if an appropriate level of RF is detected.
To use the tester as a general purpose HF RF signal generator, connect a crystal or ceramic resonator of the desired HF frequency to point C, isolate points D and E (or you may keep them connected) and take the RF output from point D. The ground must be also connected at the external circuit to which RF will be fed.

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