LTSpice schematic files for these are attached.The emitter resistor values shown are a good starting point however some adjustment to compensate for transformer parasitics may be useful to improve the output match.
Bruce Ed Palmer wrote:
I was wondering about that transformer. Thanks for the cross-reference. Ed John Miles wrote:Ed If it helps I can send you some LTSpice schematics so that you can simulate the circuit for yourself. The breadboards behave as predicted by the simulations at 10MHz. John Miles has done some preliminary phase noise measurements on his version. The transformers are wound on binocular ferrite cores. I used some 14mm (long) cores intended for 40MHz to 220MHz (I had some) operation in my breadboard which works well at 5MHz and 10Mhz.You can also use an off-the-shelf Mini-Circuits transformer for low-power applications. The T13-1 was the one I tried. I'll stick some of the plotsup on the web later tonight if possible.Residual PN is very good with this circuit, with a broadband floor near -170dBc/Hz at 10 MHz, and no excess 1/f noise relative to a passive mixer. -- john, KE5FX_______________________________________________ time-nuts mailing list -- time-nuts@febo.comTo unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nutsand follow the instructions there.
CommonEmitterTransformerFeedbackAmplifier_Type3_B_0dB.asc
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CommonEmitterTransformerFeedbackAmplifier_Type3_B_5dB.asc
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