Thanks Tom and Bob, I have been thinking of contacting Agilent for some time. I think they are a great company with some good products, but there are a few real blind spots in some current products. I also have seen in the past a genuine interest in listening. I would be willing to approach them if I could enlist your help in addressing potential changes to improve the product. Thanks; Thomas Knox
> From: li...@rtty.us > Date: Tue, 18 Feb 2014 18:00:17 -0500 > To: time-nuts@febo.com > Subject: Re: [time-nuts] strange behavior of 53230A or is the light on, > but nobody in? > > Hi > > Well at least this got me digging a little. > > If you grab a copy of the 53230A spec sheet and look under the external > reference input, it’s pretty well described. It will accept 1, 5,10 MHz as an > external reference. It will lock over a 1 ppm range with the XO option and > 0.1 ppm with the OCXO option. Based on that I’d guess they are still using > the same basic PLL approach as on the older counters (5335 era). > > The “Microsoft Windows inside” sticker on the back of the counter was a bit > of a surprise …. > > Bob > > On Feb 18, 2014, at 11:51 AM, Tom Van Baak (lab) <t...@leapsecond.com> wrote: > > > TomK, > > > > If anyone has technical contacts deep within Agilent, let's see if this > > issue can be resolved. I would have bought a 53230A when it came out a few > > years ago but my eval units showed this clock noise problem. That plus the > > poor quality of the ref out made me think the designers were cutting > > corners, or had little experience in metrology, or maybe they thought this > > was "ok" for a bench instrument. > > > > Otherwise it's a really nice counter; the first one from Agilent than can > > actually do ADEV properly (since it is a time stamping counter). > > > > I should dig out my old data and send it to you. Maybe as group we can help > > them fix the problem. > > > > /tvb > > > >> On Feb 18, 2014, at 12:10 AM, Tom Knox <act...@hotmail.com> wrote: > >> > >> I have asked Agilent > >> if stock versions of the 53230A and 53132A switched the internal > >> oscillator out of circuit with an Ext Ref signal > >> applied. I thought > >> Agilent's engineer was intentionally vague but said the oscillators were > >> indeed switched out of circuit on the counter with Ext Ref signal applied. > >> These questions were related to several 53132A's I have seen configured > >> with a small board back near the Ext Ref input (OPT H01 I think) that > >> appeared to Switch the internal reference out of circuit. Agilent would > >> not share information on the option. My question to Agilent is why sell an > >> option and be unwilling to say what it does or how your stock unit > >> functions? > >> Thomas Knox > >> > >> > >> > >>> From: t...@leapsecond.com > >>> Date: Mon, 17 Feb 2014 09:38:28 -1000 > >>> To: time-nuts@febo.com > >>> Subject: Re: [time-nuts] strange behavior of 53230A or is the light on, > >>> but nobody in? > >>> > >>> Bob, > >>> > >>> I'm wondering if you (or any else) has measured the PLL performance of > >>> the 53230-series? > >>> > >>> I agree it will "clean up the crud" but this assumes the ext ref is > >>> dirtier than the internal osc. > >>> > >>> What I found instead was that if you use a good external ref the PLL > >>> actually makes it worse. This was very disappointing. The XO version of > >>> the counter performed worse than the OCXO version even with a maser as > >>> the ext reference. Did your reading of the schematic show a way to > >>> directly use the ext ref, bypassing the noisy PLL? > >>> > >>> The other thing I found was that the ref out signal was a very polluted > >>> copy of the ref in. > >>> > >>> /tvb (i5s) > >>> > >>>> On Feb 17, 2014, at 7:04 AM, Bob Camp <li...@rtty.us> wrote: > >>>> > >>>> Hi > >>>> > >>>> If you dig into the schematics (when they supplied them … ): > >>>> > >>>> The external reference goes into a phase detector. It’s one of those > >>>> digital ones that can lock up to many inputs. You could feed 3.33333333 > >>>> MHz in as a standard input as well as 0.5, 1, 2.5, 5, and 10 MHz. The > >>>> internal oscillator (or an internal oscillator) is phase locked to the > >>>> external input through a fairly narrow analog loop. The idea is to clean > >>>> up the crud on the standard line. > >>>> > >>>> With no external reference, the PLL drops out and you go back to what > >>>> ever the local reference is. > >>>> > >>>> Yes there’s a little more to it than that and no the circuit is not > >>>> exactly the same on every counter HP ever made. > >>>> > >>>> Bob > >>>> > >>>>> On Feb 17, 2014, at 7:55 AM, wb6bnq <wb6...@cox.net> wrote: > >>>>> > >>>>> Hi Mike, > >>>>> > >>>>> The most likely answer is when you select external time base for an > >>>>> input, it disables the connection for the internal oscillator. The > >>>>> external input signal is probably also routed straight to the reference > >>>>> output jack. > >>>>> > >>>>> However, it would be good to read the manual, as they usually cover how > >>>>> those connections work. Otherwise, perhaps someone that owns one could > >>>>> provide further insight. > >>>>> > >>>>> Bill....WB6BNQ > >>>>> > >>>>> mike cook wrote: > >>>>> > >>>>>> Something that must be simple to explain, but that I can't get my head > >>>>>> round. > >>>>>> > >>>>>> I got a new 53230A. > >>>>>> When first using it, I measured my T-Bolt 10MHz using the internal > >>>>>> 10MHz timebase and it came up short of 10MHz, 9.999 998 5xx. I wasn't > >>>>>> worried about it as the counter only has a TCXO internal oscillator. > >>>>>> So I fired up my PRS10 and after leaving that on for some time, > >>>>>> connected it to Ext Ref. , changed to the ext time base and measured > >>>>>> again. This time 10.000.000.00x. Then I switched the two references, > >>>>>> measuring the PRS10 against the T-Bolt. Again I got 10MHz down to the > >>>>>> 11th digit. > >>>>>> All that looked good so I have been using it with either the PRS10 > >>>>>> locked to GPS, or the T-Bolt as the external time base. > >>>>>> > >>>>>> After leaving it on (but not inactive) for a month, I did an Autocal. > >>>>>> No problem. > >>>>>> I was wondering if that would have changed the internal time base > >>>>>> frequency, but no, using that still gave similar figures to the above. > >>>>>> > >>>>>> So at that point I decided to measure the Internal TB against my > >>>>>> reference. So I connected the Int. Ref. Out to channel 1, connected my > >>>>>> PRS10 ref to Ext. Ref In, selected the EXT time base and found that > >>>>>> the count was 10MHz dead on????? I don't get that at all. > >>>>>> > >>>>>> in summary: > >>>>>> DUT against internal TB counts < 10MHz. To me that means that the > >>>>>> internal timebase is a bit fast. Is that assumption correct? > >>>>>> DUT against Ext.Ref counts 10MHz > >>>>>> Internal TB against Ext.Ref counts 10MHz. If my assumption above > >>>>>> is correct, the count should be greater than 10MHz, no? > >>>>>> > >>>>>> Can anyone shed any light on that? > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> _______________________________________________ > >>>>>> 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. > >>>> > >>>> _______________________________________________ > >>>> 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. > >> > >> _______________________________________________ > >> 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. > > _______________________________________________ > 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.
