YES 7851.... I hope In a message dated 12/12/2018 3:43:23 PM Eastern Standard Time, rich...@karlquist.com writes:
FWIW, the HMC832 has FOM of -226. The best synth on a chip now available AFAIK has FOM of -236. That's 10 dB better. Rick N6RK On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote: > I did some phase noise measurement and the 8751 is much better then the rest > on the market > > Sent from my iPhone > >> On Dec 12, 2018, at 1:20 PM, Bob kb8tq <kb...@n1k.org> wrote: >> >> Hi >> >> Just to save others the time digging, the 7851 uses a HMC832 VCO + >> fractional N PLL on a chip as >> the heart of its synthesizer. Yet another “way to go” if building a quick >> and simple signal source. >> >> === >> >> No argument at all about other parts of the radio having their limits. PA >> performance certainly is one >> of those areas. >> >> Bob >> >>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts >>> <time-nuts@lists.febo.com> wrote: >>> >>> My feeling is >>> A Because of the low sunspot cycle the large signal performance of the RX >>> is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency >>> concept is winning but expensive >>> B The power amplifier from 100 W to 1500 Watt need to be catching up to the >>> old Collins tube Amps with negative feedback, producing - 45 dB or better >>> IMD products. >>> >>> The military amplifier are fast on , reliable , durable and expensive... >>> initially. >>> >>> The noisy blower may be a bad thing. >>> >>> I “only “ run 1 KW, and I am happy with it >>> >>> 73 de N1UL >>> >>> Sent from my iPhone >>> >>>> On Dec 12, 2018, at 10:47 AM, Bob kb8tq <kb...@n1k.org> wrote: >>>> >>>> Hi >>>> >>>> Usually on HF, the issue is large signal rejection. Phase noise very >>>> definitely >>>> gets into that part of things. Other components in the signal chain do as >>>> well. >>>> Once the synthesizer is no longer the weak link in the chain, spending more >>>> to improve it (vs spending on the other components) probably does not make >>>> a lot of sense. Since the synthesizer is *far* from ideal, that sort of >>>> begs the >>>> question of just how troublesome the other parts are and how much better a >>>> device *could* be built. >>>> >>>> This does seem to be wandering a bit from a Time related topic ….. >>>> >>>> It does illustrate the point that “good enough” may be way far away from >>>> “pretty good” and yet even more distant from “as good as it gets”. The >>>> question on any system is always “how good do you need / what are you >>>> doing?” …. >>>> >>>> Bob >>>> >>>>> On Dec 12, 2018, at 8:49 AM, jimlux <jim...@earthlink.net> wrote: >>>>> >>>>> On 12/11/18 3:26 PM, Bob kb8tq wrote: >>>>>> Hi >>>>>> As I said, just how rational using these parts in a radio …. not at all >>>>>> clear to me. >>>>>> Back when I went to school, stuff that was this noisy was not in the >>>>>> “greatest” category. >>>>>> That was a *very* long time ago. >>>>>> Oddly enough best performance synthesizers have gotten better. (as the >>>>>> posted >>>>>> presentations very clearly show). Just why a “high end” radio uses a >>>>>> less than >>>>>> ideal synthesizer likely relates more to cost (even at a price of >>>>>> thousands of dollars) >>>>>> than to anything else. >>>>> >>>>> Or "good enough" performance - driving to a 3 dB NF for a HF receiver >>>>> while maintaining good strong signal performance is probably not worth it >>>>> >>>>> >>>>>> Indeed cost also drives things like GPSDO’s and GPS modules. We often >>>>>> are not >>>>>> very eager to acknowledge that fact. >>>>>> Bob >>>>> >>>>> _______________________________________________ >>>>> time-nuts mailing list -- time-nuts@lists.febo.com >>>>> To unsubscribe, go to >>>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>>> and follow the instructions there. >>>> >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@lists.febo.com >>>> To unsubscribe, go to >>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>> and follow the instructions there. >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.