[time-nuts] Quad Driven Mixer 5 to 10 MHz Doubler Article

[Charles Steinmetz]

Brian wrote:

>Personally, I'm lazy and like the Wenzel "full wave rectifier" 
>design with a nice BPF on the output to obtain a clean 10MHz.

The advantage of the multiplier circuit is that the signal straight 
out of the mixer has excellent harmonic and 5MHz suppression.  In my 
circuit with the quadrature hybrid, 5MHz feedthrough is less than 
-45dBc and the most prominent harmonic (30MHz) is less than 
-30dBc.  The visible spurs are all odd harmonics of the 10MHz output, 
so the signal is symmetrical and for many uses does not need any 
further filtering.  I generally use a 2-pole active filter that 
reduces the 30MHz to better than -55dBc, and if I need to get crazy I 
can add a simple series LC at the output to get the 30MHz below 
-70dBc.  This strategy minimizes the risk of temperature-dependent 
phase shift from the steep filter that would be necessary to reduce 
the spurs to those levels following a diode doubler.

Best regards,

Charles