[time-nuts] XOR frequency doubler question 5/10 Mhz

[paul swed]

Experimenting with a 74ls86 XOR doubler for 5 to 10 Mhz. Typically this
would use a 90 degree phase shift to the other gate. The gate acting as a
mixer to produce 10 Mhz.
The reason to experiment is that I have noticed most of the doubler
discussions take a 5 Mhz square wave filter it to a sine wave, feed it to a
multiplier scheme and then filter the output. The 7486 method eliminates
one of those processes.
I have accurate delay lines I can adjust in 2 ns increments (Allen Aviation
lump LC).
The output is a semi asymmetrical square wave due to some gate timing I
need to deal with if possible.
Setting the delay taps to 90 degrees produces a 10 MHz output with 5 and 15
Mhz 8-10 db down. Lots of other higher frequency outputs. At this point I
have no filtering on the output of the 7486.
Purposely mis-adjusting the taps sets either the 5 Mhz or 15 Mhz level
higher.

Other noise and such are many DB down 50 plus.
Why is this a bad method as compared to our typical time-nuts discussions?
Regards
Paul
WB8TSL