- #1
Enthalpy
- 667
- 4
Greetings to all HF enthusiasts!
This is a first frequency multiplier, but beware I haven't tested it (and won't in a foreseeable future), so whether it improves over existing diagrams remains to be seen.
This diagram is to harvest an odd harmonic; connect the collectors together at one end of the coil to harvest an even harmonic.
A balanced mixer could be built similar to the multiplier, with the LO input between the input secondary's middle point and the ground; adding two PNP would make a doubly-balanced mixer. I doubt such a mixer has advantages over a diode bridge.
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Unusually, the multiplier has bipolars in common base without a power supply. All power comes from the input signal.
Stability isn't guaranteed, as the input signal brings power to the circuit. Beware many recent bipolars accept only a common-emitter configuration. I'd take only the necessary Ft, and wouldn't put the output tuning capacitor near to the collectors.
Marc Schaefer, aka Enthalpy
(Click on the thumbnail to magnify)
This is a first frequency multiplier, but beware I haven't tested it (and won't in a foreseeable future), so whether it improves over existing diagrams remains to be seen.
This diagram is to harvest an odd harmonic; connect the collectors together at one end of the coil to harvest an even harmonic.
A balanced mixer could be built similar to the multiplier, with the LO input between the input secondary's middle point and the ground; adding two PNP would make a doubly-balanced mixer. I doubt such a mixer has advantages over a diode bridge.
-----
Unusually, the multiplier has bipolars in common base without a power supply. All power comes from the input signal.
- The bipolars conduct at some 0.7V input voltage but drop only about 0.4V; this behaviour is more brutal than a diode, and shall transfer a bigger proportion of the input power more concentrated in the harmonics, so I hope losses improve over a diode frequency multiplier;
- The emitter current determines essentially the collector current, so imbalances between the transistors are less important than with the traditional two-transitors multiplier; operation nearer to Ft improve as well;
- The output power is well defined and should depend less on the input power than with diodes or traditional transistor diagrams.
Stability isn't guaranteed, as the input signal brings power to the circuit. Beware many recent bipolars accept only a common-emitter configuration. I'd take only the necessary Ft, and wouldn't put the output tuning capacitor near to the collectors.
Marc Schaefer, aka Enthalpy
(Click on the thumbnail to magnify)