Re: Hairpin mixers with sub-LO Drive

David Jones <david.g6feo@...>


The DMC ASK 'brick' 23GHz radios used this type of circuit for their 2nd
IF on the receive side.

Assume a transmit frequency of 23GHz, then the receive could be 23GHz +
or - 1232MHz, then to get from 1232MHz to 72MHz a hairpin mixer was
used, with a cheap pc style 580MHz can oscillator which was doubled to
1160MHz in the mixer.

Do you want one to play with? I can put one in the post to you.

I used one of these boards to make a crude 23cms receiver, it worked
quite well.

73, David.

On Thu, 2013-01-10 at 19:03 +0000, Andy Talbot wrote:
Double balanced mixers have a quite respectable performance if used
with a LO at an odd submultiple of the wanted freqeuncy. This is a
particulalrly effective way of simplifying hardware where a wideband
DBM is used that actually covers the frequency of the sub-multiple LO.
MiniCircuits even document many DBMs at harmonics of LO and RF.

But... Has anyone tried using the simple hairpin two diode single
balanced mixer with drive at an odd subharmonic? If the LO is
applied to the hairpin, then the phase shift ending up at the diodes
will be reduced pro-rata, eg 60 degrees phase delta for LO/3 drive.
SO somewhat messy setup, but the resulting harmonic current in the
mixer will still be at the resulting 180 deg at teh wanted LO, so it
may work to some extent. And even harmonics won't get cancelled

Just wondering before I knock up a breadboard



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