LA7MI Stein Torp writes that he has tested a mixer which was used in a
Redifon mobile transceiver in the late 60's, but using modern
components. The input transformer is a pentofilar wound type with 5x
3turns (0.25mm enam cu wire), see drawing for the type of two hole
core used in the transformers.T2 and T3 are wound with 2x 3turns 0.3mm
wire. With input on 80m and 10.7MHz IF (LO = 14.5MHz) 3rd order IP on
the input was measured to +20dB, and the strange is that output
termination is not critical at all. It is possible to terminate it
with an xtal filter and still obtain +20dBm, which is not at all
possible with a ringmodulator. Measured the 1dB compression point to
+10dBm, see http://www.noding.com/la8ak/12345/n16.htm

73
Jan-Martin
LA8AK
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J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm