[time-nuts] Ebay FE-5680A Rb: Are they that good?

Marco IK1ODO -2 ik1odo at spin-it.com
Fri Dec 9 09:54:59 EST 2011

At 14:21 09-12-11, you wrote:
>Think you are correct for most things we do.
>However in communications for mixing and such a sine wave is desirable and
>a very clean output to minimize things like IMD and other products as we
>get the 10 MC to its final frequency. Since you are a ham you may
>appreciate that.

Hello Paul,

I understand, but don't agree 100% :-) - I mean, doing radio either 
you use the 10 MHz for syncing oscillators in you chain (I do that 
for EME, all is derived from a FRK-HLN), or you use the 10 MHz 
directly to a mixer. The mixer usually is inherently non linear; if 
you look at the current in the diodes of a ring mixer, it is almost 
squared. More it is squared, more abrupt is the diode switching, 
better the mixer dynamic range. And many mixers are sensitive to 
harmonics (see Tayloe mixer) of the input signal or use harmonic 
mixing schemes (see any S/A), only possible if the mixer current is 
highly non-sinusoidal.
So, I agree with Javier about the search for existence of low lever 
spurious signals, but don't understand the need to have a (very) low 
harmonic content. Oh, well, to have too many harmonics is a bad thing 
- one time I had radiation problems from a coax feeding a 10 MHz 
squared signal, with components over 100 MHz - but this is an extreme case.

73 - Marco IK1ODO / AI4YF

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