Message	Date	From	Subject
5838	2011-02-15 02:15:39	iapizloj	Seco 500 crystalignmeter
Folks, on my unending search for a crystal tester, I read many years ago that this one was able to test all kind of xtals. My search was fruitful and a kind soul sent me the schematics. It is now placed on the Files section under this very subject. There is a 2N1225 oscillator for the xtal, and an AF oscillator for modulating purposes. A 1 mA meter servers as an indicator. What is really puzzling in the schematics is the wiring of the sliding switch, which has 4 positions: A. Untuned oscillator. Good for 1-20 MHz xtal testing. OFF (Oscillator OFF, but meter is available for voltage or current tests, as well as for field strenght meter) C. Tone modulated output. D. Unmodulated RF out. C and D are used for Third overtone transmitting xtals (for CB). I guess I would have to be thirty years older in order to understand such kind of schematics. If someone knows better, please give me a hand, as I would like to replicate the circuit. Be well jon, ea2sn

Folks,

on my unending search for a crystal tester, I read many years ago that this one was able to test all kind of xtals.

My search was fruitful and a kind soul sent me the schematics. It is now placed on the Files section under this very subject. There is a 2N1225 oscillator for the xtal, and an AF oscillator for modulating purposes. A 1 mA meter servers as an indicator.

What is really puzzling in the schematics is the wiring of the sliding switch, which has 4 positions:
A. Untuned oscillator. Good for 1-20 MHz xtal testing.
OFF (Oscillator OFF, but meter is available for voltage or current tests, as well as for field strenght meter)
C. Tone modulated output.
D. Unmodulated RF out.
C and D are used for Third overtone transmitting xtals (for CB).

I guess I would have to be thirty years older in order to understand such kind of schematics. If someone knows better, please give me a hand, as I would like to replicate the circuit.

Be well
jon, ea2sn