EMRFD Message Archive 5839

Message Date From Subject
5839 2011-02-15 10:05:55 Brooke Clarke Re: Digest Number 1295
Hi Jon:

I find for schematics that have a function switch, like this one, it
helps to erase those components that are not being used so that you end
up with different schematics for each function. Would you send to me
directly the missing pages from the manual? My crystal web pages:
http://www.prc68.com/I/Xam.html <- Crystal Activity meter (similar to
the Seco 500)
http://www.prc68.com/I/Xec.shtml <- crystal equivalent circuit
http://www.prc68.com/I/Xtal.shtml <- crystals
http://www.prc68.com/I/VC2000.shtml <- modern combined frequency counter
and crystal tester

Have Fun,

Brooke Clarke, N6GCE

> 1. Seco 500 crystalignmeter
> Posted by: "iapizloj" jon.iza@gmail.com iapizloj
> Date: Tue Feb 15, 2011 2:15 am ((PST))
> 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