Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Bruce and others, Thank you for the assistance. Seems that the TADD-1 will meet my needs, I will probably acquire one in the near future. Steve K8JQ Bruce Griffiths wrote: > Steve wrote: > >> Thanks for the info Bruce. >> >> I'm planning to use the Trimble Thunderbolt as the 10MHz source. >> >> The phase noise characteristics of that device are on the Trimble web >> site. I'm not versed enough in the specifications to call it good, bad >> or mediocre with respect to phase noise. Thoughts? >> >> Thanks. >> >> Steve K8JQ >> >> >> > Steve > > If one compares TvB's plot of the phase noise of a Thunderbolt with John > Ackermann's plot of the phase noise of a TADD-1 at 10MHz. > Then the phase noise floor of this particular Thunderbolt is lower than > the phase noise floor of the TADD-1 at the particular gain used in > John's test. > Thus using the TADD-1 at this gain will degrade the noise floor of that > particular Thunderbolt by about 7dB. > However at 1Hz and 10Hz the phase noise of the Thunderbolt exceeds that > of the TADD-1 by 15dB or more so the phase noise of that Thunderbolt > will not be significantly degraded by the TADD-1 at those offset > frequencies. > > Distribution amplifiers with lower noise floors and equivalent or better > reverse isolation do exist but tend to be expensive. > A design employing cascaded common base stages can have a significantly > lower phase noise floor. > > Bruce > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > -- Read The Patriot It's Right -- It's Free http://PatriotPost.US/subscribe/ Veritas vos Liberabit ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Steve wrote: > Thanks for the info Bruce. > > I'm planning to use the Trimble Thunderbolt as the 10MHz source. > > The phase noise characteristics of that device are on the Trimble web > site. I'm not versed enough in the specifications to call it good, bad > or mediocre with respect to phase noise. Thoughts? > > Thanks. > > Steve K8JQ > > Steve If one compares TvB's plot of the phase noise of a Thunderbolt with John Ackermann's plot of the phase noise of a TADD-1 at 10MHz. Then the phase noise floor of this particular Thunderbolt is lower than the phase noise floor of the TADD-1 at the particular gain used in John's test. Thus using the TADD-1 at this gain will degrade the noise floor of that particular Thunderbolt by about 7dB. However at 1Hz and 10Hz the phase noise of the Thunderbolt exceeds that of the TADD-1 by 15dB or more so the phase noise of that Thunderbolt will not be significantly degraded by the TADD-1 at those offset frequencies. Distribution amplifiers with lower noise floors and equivalent or better reverse isolation do exist but tend to be expensive. A design employing cascaded common base stages can have a significantly lower phase noise floor. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
> Thanks for the info Bruce. > > I'm planning to use the Trimble Thunderbolt as the 10MHz source. > > The phase noise characteristics of that device are on the Trimble web > site. I'm not versed enough in the specifications to call it good, bad > or mediocre with respect to phase noise. Thoughts? > > Thanks. > > Steve K8JQ Here's an old plot of a random Thunderbolt I tested: Ignore the spurs (test setup problem). http://www.leapsecond.com/museum/tbolt/tbolt_pn.gif /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Tom's unit had the bandpass filter installed, and as Bruce noted I've regretted ever putting the holes on the board for it -- my saying is that "every resonator is a thermometer"! The prototype that Tom tested without a filter had much better tempco, and I suspect that the filter-less production version would be closer to that performance. I'm hoping to do my own tempco testing one of these days, but things beyond my control have gotten me way behind on the project list lately. John Didier Juges said the following on 03/28/2008 02:09 PM: > The phase plots on tvb's web site > http://www.leapsecond.com/pages/tadd-1/3phase2.gif show that the device's > temperature was never stabilized. The closest to being stable is at the 29 > minute point on that plot. > > Particularly when the phase value goes up (not sure if it's when temperature > goes up or down), because the phase was still changing at a pretty high rate > when the compressor changed state. I think Tom should rerun that test with a > much slower cycling, to make sure the phase was stable before the compressor > was turned on (or off). Since the phase excursion was not complete, the > 150pS/degree is probably underestimated. > > My guess is that the period should be at least doubled. > > Didier KO4BB > >> -Original Message- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Mock >> Sent: Friday, March 28, 2008 12:29 AM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] TADD-1 six channel RF distribution amplifier >> >> >> Bruce Griffiths wrote: >>> Steve wrote: >>>> I'm thinking about using the TAPR TADD-1 six channel RF >> distribution >>>> amplifier to distribute the 10MHz output of my Trimble >> Thunderbolt to >>>> a few pieces of test equipment. >>>> >>>> What does the TADD-1 do to the phase noise characteristics of its >>>> outputs as compared to the phase noise characteristics of >> its input? >>>> Improve? Degrade? Little or no change? >>>> >>>> Thanks. >>>> >>>> Steve K8JQ >>>> >> I've been using a TADD-1 for about 6-months now and I'm quite >> happy with it. You certainly can't beat the price. I added >> the optional 10MHz BPF and tuned it with a tracking generator >> and spectrum analyzer. The outputs are very clean. >> >> I've never tried to measure phase noise, but the op amps and >> the rest of the circuit seem to be good choices to me. tvb >> did some analysis of the box you might find interesting: >> http://www.leapsecond.com/pages/tadd-1/ >> >> jeff >> >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, >> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> No virus found in this incoming message. >> Checked by AVG. >> Version: 7.5.519 / Virus Database: 269.21.8/1339 - Release >> Date: 3/22/2008 4:43 PM >> >> > > No virus found in this outgoing message. > Checked by AVG. > Version: 7.5.519 / Virus Database: 269.21.8/1339 - Release Date: 3/22/2008 > 4:43 PM > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
> The phase plots on tvb's web site > http://www.leapsecond.com/pages/tadd-1/3phase2.gif show that the device's > temperature was never stabilized. The closest to being stable is at the 29 > minute point on that plot. > > Particularly when the phase value goes up (not sure if it's when temperature > goes up or down), because the phase was still changing at a pretty high rate > when the compressor changed state. I think Tom should rerun that test with a > much slower cycling, to make sure the phase was stable before the compressor Agreed. Actually, I don't have that A/C anymore so future tempco tests won't have that rapid cycling. > was turned on (or off). Since the phase excursion was not complete, the > 150pS/degree is probably underestimated. > > My guess is that the period should be at least doubled. Yeah, I think so. The main conclusion I had when I made those plots was that the input filter was a bad idea, at least if the TADD was to be used for precision work. > Didier KO4BB /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Thanks for the info Bruce. I'm planning to use the Trimble Thunderbolt as the 10MHz source. The phase noise characteristics of that device are on the Trimble web site. I'm not versed enough in the specifications to call it good, bad or mediocre with respect to phase noise. Thoughts? Thanks. Steve K8JQ Bruce Griffiths wrote: > Steve wrote: > >> I'm thinking about using the TAPR TADD-1 six channel RF distribution >> amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a >> few pieces of test equipment. >> >> What does the TADD-1 do to the phase noise characteristics of its >> outputs as compared to the phase noise characteristics of its input? >> Improve? Degrade? Little or no change? >> >> Thanks. >> >> Steve K8JQ >> >> >> > Like any distribution amplifier it always degrades the signal phase noise. > Whether the amount of degradation is significant or not depends on the > phase noise characteristics of your source. > > If your signal source phase noise is 10dB greater than the intrinsic > phase noise of the distribution amplifier than the increase in the phase > noise at the distribution amplifier is relatively insignificant. > > Thus you need to know the phase noise characteristics of your source and > of the distribution amplifier (when set to the gain you need). > > The phase noise characteristics of the distribution amplifier vary with > its gain. > > The phase noise of your source and a distribution amplifier vary with > the frequency offset at which they are measured. > > What source are you intending to use? > Do you know its phase noise characteristics? > > Bruce > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
The phase plots on tvb's web site http://www.leapsecond.com/pages/tadd-1/3phase2.gif show that the device's temperature was never stabilized. The closest to being stable is at the 29 minute point on that plot. Particularly when the phase value goes up (not sure if it's when temperature goes up or down), because the phase was still changing at a pretty high rate when the compressor changed state. I think Tom should rerun that test with a much slower cycling, to make sure the phase was stable before the compressor was turned on (or off). Since the phase excursion was not complete, the 150pS/degree is probably underestimated. My guess is that the period should be at least doubled. Didier KO4BB > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Mock > Sent: Friday, March 28, 2008 12:29 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] TADD-1 six channel RF distribution amplifier > > > Bruce Griffiths wrote: > > Steve wrote: > >> I'm thinking about using the TAPR TADD-1 six channel RF > distribution > >> amplifier to distribute the 10MHz output of my Trimble > Thunderbolt to > >> a few pieces of test equipment. > >> > >> What does the TADD-1 do to the phase noise characteristics of its > >> outputs as compared to the phase noise characteristics of > its input? > >> Improve? Degrade? Little or no change? > >> > >> Thanks. > >> > >> Steve K8JQ > >> > > I've been using a TADD-1 for about 6-months now and I'm quite > happy with it. You certainly can't beat the price. I added > the optional 10MHz BPF and tuned it with a tracking generator > and spectrum analyzer. The outputs are very clean. > > I've never tried to measure phase noise, but the op amps and > the rest of the circuit seem to be good choices to me. tvb > did some analysis of the box you might find interesting: > http://www.leapsecond.com/pages/tadd-1/ > > jeff > > > ___ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, > go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > No virus found in this incoming message. > Checked by AVG. > Version: 7.5.519 / Virus Database: 269.21.8/1339 - Release > Date: 3/22/2008 4:43 PM > > No virus found in this outgoing message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.21.8/1339 - Release Date: 3/22/2008 4:43 PM ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Steve said the following on 03/27/2008 09:35 PM: > I'm thinking about using the TAPR TADD-1 six channel RF distribution > amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a > few pieces of test equipment. > > What does the TADD-1 do to the phase noise characteristics of its > outputs as compared to the phase noise characteristics of its input? > Improve? Degrade? Little or no change? > > Thanks. > > Steve K8JQ > I did some testing a while ago on a TADD-1 as well as an HP 5087A and Spectracom 8140T line amplifier. At 5 MHz, for offsets above 1 Hertz, the TADD-1 is better than the HP amp (the 5087A is better at very low offsets, though). The results are at http://www.febo.com/pages/amplifier_phase_noise/ I've learned a bit about technique since I did this test, and want to rerun it one of these days. But the data shouldn't be more than a few dB off. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Jeff Mock wrote: > Bruce Griffiths wrote: > >> Steve wrote: >> >>> I'm thinking about using the TAPR TADD-1 six channel RF distribution >>> amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a >>> few pieces of test equipment. >>> >>> What does the TADD-1 do to the phase noise characteristics of its >>> outputs as compared to the phase noise characteristics of its input? >>> Improve? Degrade? Little or no change? >>> >>> Thanks. >>> >>> Steve K8JQ >>> >>> > > I've been using a TADD-1 for about 6-months now and I'm quite happy with > it. You certainly can't beat the price. I added the optional 10MHz BPF > and tuned it with a tracking generator and spectrum analyzer. The > outputs are very clean. > > I've never tried to measure phase noise, but the op amps and the rest of > the circuit seem to be good choices to me. tvb did some analysis of the > box you might find interesting: > http://www.leapsecond.com/pages/tadd-1/ > > jeff > > Jeff As John Ackermann has often pointed out using a high Q bandpass filter is a particularly bad idea if phase shift tempco is important. The best way to eliminate harmonics is to use high Q traps tuned to the unwanted harmonics, these have litle phase shift (and associated tempco) at the fundamental. If you do use a high Q bandpass filter it may be necessary to regulate its temperature to stabilise its phase shift. Some care in selection of filter components is also required to avoid significantly increasing flicker phase noise. John has far some distribution amplifier phase noise comparison data at: http://www.febo.com/pages/amplifier_phase_noise/ Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Bruce Griffiths wrote: > Steve wrote: >> I'm thinking about using the TAPR TADD-1 six channel RF distribution >> amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a >> few pieces of test equipment. >> >> What does the TADD-1 do to the phase noise characteristics of its >> outputs as compared to the phase noise characteristics of its input? >> Improve? Degrade? Little or no change? >> >> Thanks. >> >> Steve K8JQ >> I've been using a TADD-1 for about 6-months now and I'm quite happy with it. You certainly can't beat the price. I added the optional 10MHz BPF and tuned it with a tracking generator and spectrum analyzer. The outputs are very clean. I've never tried to measure phase noise, but the op amps and the rest of the circuit seem to be good choices to me. tvb did some analysis of the box you might find interesting: http://www.leapsecond.com/pages/tadd-1/ jeff ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TADD-1 six channel RF distribution amplifier
Steve wrote: > I'm thinking about using the TAPR TADD-1 six channel RF distribution > amplifier to distribute the 10MHz output of my Trimble Thunderbolt to a > few pieces of test equipment. > > What does the TADD-1 do to the phase noise characteristics of its > outputs as compared to the phase noise characteristics of its input? > Improve? Degrade? Little or no change? > > Thanks. > > Steve K8JQ > > Like any distribution amplifier it always degrades the signal phase noise. Whether the amount of degradation is significant or not depends on the phase noise characteristics of your source. If your signal source phase noise is 10dB greater than the intrinsic phase noise of the distribution amplifier than the increase in the phase noise at the distribution amplifier is relatively insignificant. Thus you need to know the phase noise characteristics of your source and of the distribution amplifier (when set to the gain you need). The phase noise characteristics of the distribution amplifier vary with its gain. The phase noise of your source and a distribution amplifier vary with the frequency offset at which they are measured. What source are you intending to use? Do you know its phase noise characteristics? Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
