Wow those are good results. I have to say the thread was one that motivated me to buy parts and then to do something. If Luciano will be writing this up, I look forward to it. Always a good read with excellent pictures. I do not have a particular need just wanted to see what the suggestions would do. I do have a question. The doubler really would work for anything as I recall. 10 mc in 20 out etc. Certainly some output adjustments needed.
Other comment injection locking is always interesting to me because you can inject at quite low frequencies. I would like to see some of the details from Henry. Regards Paul WB8TSL On Tue, Jun 14, 2011 at 3:00 PM, Bruce Griffiths <[email protected] > wrote: > Luciano followed this up off list and found that the suggested improvements > (and others) worked well. > The performance now closely mimics that of the simulations. > Final results: > > Input range +6 to +13 dBm > Gain 0dB ± 1 dB on the input range. > Output harmonics and subharmonics -60 dBc > > He intends to write an article on it. > > As yet he hasn't been able to measure the phase noise as this requires > using a pair of doublers with their outputs in phase quadrature. > > Bruce > > > paul swed wrote: > >> Lets see feb to june. Time to restart this thread. >> I found this a very interesting thread and finally ordered the >> transformers >> from mini circuits. Needed some other parts and had enough of an order to >> make sense. >> I do plan to build the circuit and try some of the comments suggested to >> see >> what happens. >> Though this may take a bit of time. Lots of other things to work on. >> Regards >> Paul >> WB8TSL >> >> On Wed, Feb 16, 2011 at 9:11 AM, paul swed<[email protected]> wrote: >> >> >> >>> This has been a great read. >>> Though I don't have a need at the moment. I may assemble this with the >>> various comments just to try it out. Dead bug style. >>> Regards >>> >>> >>> On Wed, Feb 16, 2011 at 8:46 AM, Paramithiotti, Luciano Paolo S< >>> [email protected]> wrote: >>> >>> >>> >>>> Bruce, >>>> I have collected yours comments, I hope they will be usefull for my next >>>> doubler version. >>>> A question: do you have ever made a physical doubler like this? if so, >>>> can >>>> you show us the schematic, photos and results of measurements made? >>>> >>>> Luciano >>>> >>>> Luciano P. S. Paramithiotti >>>> >>>> >>>> >>>> -----Original Message----- >>>> From: [email protected] [mailto:[email protected]] On >>>> Behalf Of Bruce Griffiths >>>> Sent: martedì 15 febbraio 2011 22.19 >>>> To: Discussion of precise time and frequency measurement >>>> Subject: Re: [time-nuts] Advanced 5 to 10 MHz doubler >>>> >>>> Simulation using LTSpice confirms that the 2N3904's actually saturate in >>>> this circuit. >>>> The phase noise performance will be poor. >>>> The transistor conduction angle is also poorly defined and significant >>>> conduction overlap due to saturation may render the circuit ineffective >>>> at >>>> high frequencies. >>>> >>>> The attached circuit schematic using a 1:4 (impedance ratio) input >>>> transformer will work much better and has a relatively well defined >>>> large >>>> signal input impedance. >>>> The output filter can be elaborated by replacing the 80pF caps with a >>>> combination of series tuned LC traps and a smaller shunt capacitance to >>>> reduce the level unwanted components. >>>> Suitable 100uH inductors (with SRF> 20MHz) are readily available from >>>> Farnell/element14. >>>> The output impedance is relatively low and a better match to 50 ohms may >>>> be achieved by adding a suitable low phase noise output buffer amp >>>> stage. >>>> Alternatively a 4:1 impedance ratio transformer can be used at the >>>> collector node with its primary shunted by a 200 ohm resistor. >>>> >>>> Any balancing circuitry (should this be necessary) should be implemented >>>> at the BJT emitters as any attempt to do this at the collectors will be >>>> ineffective. >>>> >>>> Bruce >>>> >>>> Bruce Griffiths wrote: >>>> >>>> >>>>> Paramithiotti, Luciano Paolo S wrote: >>>>> >>>>> >>>>>> http://www.timeok.it/files/5_to10_mhz_advanced_doubler.pdf >>>>>> >>>>>> >>>>>> >>>>>>> This design appears to have gone somewhat astray. >>>>>>> high impedance unless of course the transistors enter saturation in >>>>>>> which case the phase noise performance will be severely degraded. >>>>>>> The best place for a balance adjustment circuit is actually in the >>>>>>> emitter circuit. >>>>>>> >>>>>>> >>>>>> *The collector balancing work correctly and is more simple to >>>>>> >>>>>> >>>>> implement. >>>> >>>> >>>>> >>>>>> >>>>> I contend that the collector balancing technique you use only works >>>>> because the doubler isn't operating correctly. >>>>> With a high impedance collector output it would be relatively >>>>> ineffective unless the balancing resistance is increased to a level >>>>> that degrades the phase noise performance or saturation occurs. >>>>> >>>>> >>>>>> The description of the biasing is misleading in that the actual bias >>>>>>> level that sets the crossover current is determined by the signal >>>>>>> dependent voltage>across the two 0.1uF capacitors in the emitter. >>>>>>> With a 1:1 input transformer the quoted figure of 35 ohms for the >>>>>>> input impedance seems excessive for large signal operation of the CB >>>>>>> stages unless of>course they saturate. >>>>>>> >>>>>>> >>>>>> *the input impedance is 35 Ohms @ 0dBm as measured with network >>>>>> vector analyzer. It can be upgraded to 50 ohms adding resistance on >>>>>> emitters, with some gain reduction and probably less phase noise. I >>>>>> will do some modification in the next future, including an input 6 >>>>>> Mhz low pass filter. As you know, the input signal have to be pure >>>>>> sinewave to avoid unsymmetrical positive and negative half wave and >>>>>> obvious unbalaced output and high harmonics contens. I will test also >>>>>> the common emitter configuration to better isolate the doubler from >>>>>> the input impedance and level variations. Regarding the input level I >>>>>> have setup it's range, as my personal standard,from +7 to +13 dBm. >>>>>> >>>>>> >>>>>> >>>>> I thought as much, the large signal input impedance (this is far more >>>>> important than the small signal value) will be much lower. >>>>> Since the bias shifts with input signal level the small signal input >>>>> impedance that you measured is of little value. >>>>> >>>>> >>>>> >>>>>> It would also appear that the 20MHz tank 5.6uH + 12pF as drawn is >>>>>>> inappropriate in that it inevitably leads to saturated operation. >>>>>>> A series resonant 20MHz tank from the collector node to ground would >>>>>>> be a better choice. >>>>>>> >>>>>>> >>>>>> * The LC on collector is to adapt the impedance between the doubler >>>>>> and the filter and to cut the higher harmonics. The filter itself >>>>>> contain trap for 15 20 and 30 Mhz. >>>>>> >>>>>> >>>>>> >>>>> Maybe so, but the filter input topology adopted is inappropriate for >>>>> low phase noise and avoiding saturation. >>>>> Attempting to match the (poorly predictable and varying - with >>>>> temperature and input signal level) collector output impedance to the >>>>> filter input impedance is misguided, just treat the output as a high >>>>> impedance source. The 4:1 (impedance ratio) output transformer should >>>>> suffice, if necessary you can add a 200 ohm resistor in shunt from the >>>>> collector node to Vcc if you need a 50 ohm output impedance. In >>>>> practice it may be better to buffer the output with a series >>>>> transformer feedback stage with well defined output impedance. Series >>>>> resonant LC traps from the doubler collector node to ground should be >>>>> more effective than parallel resonant series traps in that the high >>>>> frequency component amplitudes at the doubler collector will be >>>>> significantly reduced rather than enhanced by the filter. >>>>> >>>>> >>>>> >>>>>> A snapshot or even a sketch of the collector voltage waveforms would >>>>>>> be useful in showing that the transistors saturate or not. >>>>>>> >>>>>>> >>>>>> *Actually the prototype is gone to friend's home and I cannot do any >>>>>> more measure on it. My next prototype's pubblication will be complete >>>>>> of collector voltage waveform to better understand the working >>>>>> condition of the doubler stage. I think the 2N3904 is not the best >>>>>> solution, i will test some more devices and bias point. >>>>>> >>>>>> >>>>>> >>>>> At 10MHz you will find that most wideband transistors will be noisier. >>>>> However using transistors with a lower base spreading resistance than >>>>> the 2N3904 may be useful. >>>>> >>>>> >>>>>> Thank you >>>>>> Luciano >>>>>> >>>>>> note: I'm not a genius, I just try to enjoy myself. If someone follow >>>>>> me, is at his own risk. >>>>>> >>>>>> >>>>>> >>>>>> Luciano P. S. Paramithiotti >>>>>> >>>>>> >>>>>> >>>>>> >>>>> Bruce >>>>> >>>>> >>>>> _______________________________________________ >>>>> time-nuts mailing list -- [email protected] To unsubscribe, go to >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> and follow the instructions there. >>>>> >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>>> >>>> >>> >>> >>> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
