[time-nuts] New Member + Basic Questions

Rob Sherwood. rob at nc0b.com
Fri Jan 15 05:58:50 UTC 2016 

The 8660 is a rather messy generator with five loops.  Its phase noise spec within a 30 kHz bandwidth is nominally 4 dB worse than an HP 3336C. Of course the frequency range of the 8660 is vastly greater than the 3336C, depending on the plugin. There were 4 versions of the 8660, A, B, C & D. I mention the 3336C because while a very handy synthesizer, its phase noise is terrible compared to the 8640A/B. It depends on what you want to do with your generator. As you said, if it can be purchased and shipped for $100, why not. Alignment of the 8660 is a pain, so expect a project. Hopefully it gets packed properly. Shipping damage of large and heavy test equipment is a really big problem.

Rob, NC0B

Sent from my iPad

> On Jan 14, 2016, at 4:02 PM, "Nathan Johnson" <jdownj at gmail.com> wrote:
> 
> 
> 
> What does the group think of the HP 8660? Just scored a broken one too cheap to
> pass up. I know it's not gonna be the last signal generator I buy, but for under
> $100 shipped it should be an interesting project.
> Nathan KK4REY
> 
> Sent using CloudMagic Email
> [https://cloudmagic.com/k/d/mailapp?ct=pi&cv=7.4.15&pv=9.1&source=email_footer_2]
> On Tue, Jan 12, 2016 at 02:50, Discussion of precise time and frequency
> measurement <time-nuts at febo.com> wrote:
> Robs correct on that front. Did not have time to respond till now.
> The 8640 is not some sort of synthesized gen.
> But it has one of the lowest noise floors of any generator.
> So I have several of them and then the synthesized gens like those
> mentioned.
> 
> Hear that sucking sound?
> Its quicksand.
> 
> Regards
> Paul
> WB8TSL
> 
>> On Mon, Jan 11, 2016 at 3:54 PM, Rob Sherwood. <rob at nc0b.com> wrote:
>> 
>> It is more of a counter-assisted drift stabilizer than a true phase lock
>> as would happen if locking a 10811 to an external standard. Rob, NC0B
>> 
>> Sent from my iPad
>> 
>>> On Jan 11, 2016, at 1:00 PM, "bownes" <bownes at gmail.com> wrote:
>>> 
>>> 
>>> 
>>> 
>>> The 8640 will lock to an external 5Mhz reference. That's what the BNC in
>> the heatsink is for. At least that is where it is on mine.
>>> 
>>> The trick is doing a good divide by two.
>>> 
>>> However, that said, the 8640 tops out at ~1024MHz, which if you get
>> interested in even the lower microwaves, is not quite enough.
>>> 
>>> 
>>> 
>>> Bob
>>> KI2L
>>> 
>>>> On Jan 11, 2016, at 09:47, Rob Sherwood. <rob at nc0b.com> wrote:
>>>> 
>>>> The HP 8647A may be the worst signal generator HP ever made. The 8656B
>> won't even go down low enough in level to make a noise floor measurement on
>> a modern transceiver. Sure you can add external attenuation, but you won't
>> know about how much leakage is occurring. Otherwise why wouldn't HP have
>> added another 15 dB attenuation in the box? That is why I mentioned the
>> 8657B. Yes the 8662A's reliability issue is the power supply. No question
>> not a starter generator. The 8642A was never intended for field repair,
>> but it is the only generator with low enough phase noise to test top radios
>> today, and something a ham could afford. Again, not the first sig gen that
>> should be on your list
>>>> 
>>>> Rob, NC0B
>>>> Sent from my iPad
>>>> 
>>>>> On Jan 11, 2016, at 8:01 AM, "Nathan Johnson" <jdownj at gmail.com>
>> wrote:
>>>>> 
>>>>> 
>>>>> 
>>>>> I really appreciate all the help. I really like that Ref0 combination,
>> I don't
>>>>> see any Ref1s available right now, but you are saying that any decent
>>>>> GPS+Arduino can substitute? Should I be looking in the archives for
>> that, or is
>>>>> there a website?
>>>>> Minor clarification to my earlier post about the signal gen, I am
>> aware that the
>>>>> 8640 won't lock to an external reference. I had intended that to read
>>>>> 8640-something or 50-something. I'm watching an 8647 and an 8656b on
>> the usual
>>>>> site at the moment. That 8662 looks beautiful, but it's a huge
>> investment for a
>>>>> piece of old gear that has a reputation for being a bit... Cranky and
>>>>> opinionated. I have no practical need for that now, so I won't sign up
>> for that
>>>>> kind of challenge until I do.
>>>>> I'm quite familiar with how this stuff multiplies, I have a Tektronix
>> scope
>>>>> collection, and have been a lurker on the TekScopes list for about a
>> year. There
>>>>> is a running joke on that list about "scope acquisition disorder". I'm
>> pretty
>>>>> sure that I'm infected, but I only have 5 scopes in the house at the
>> moment, so
>>>>> it's not that bad... Yet!
>>>>> 
>>>>> Nathan KK4REY
>>>>> Sent using CloudMagic Email
>>>>> [
> https://cloudmagic.com/k/d/mailapp?ct=pi&cv=7.4.15&pv=9.1&source=email_footer_2
>> ]
>>>>> On Mon, Jan 11, 2016 at 04:28, Discussion of precise time and frequency
>>>>> measurement <time-nuts at febo.com> wrote:
>>>>> Good thread everyone.
>>>>> Nathan you have received a lot of wisdom and humor today.
>>>>> Yes for sub $200 you can be in good shape.
>>>>> If lucent remember a Ref0 needs an arduino and a good GPS 1 PPS.
>>>>> Though frankly even neo6s play well.
>>>>> If a Ref1 it has a GPS in and no need for the arduino. The $175 gets
>> you a
>>>>> ref1 and ref0 combo that tie together usually with a cable thats
>> shipped
>>>>> with the units.
>>>>> Mine were brand spanking new. NOS.
>>>>> Good luck.
>>>>> To Ron ohhhh yes no shed or anything but the gear builds up. Darn
>> thing is
>>>>> this stuff actually last longer then an iPhone99X due out tomorrow I am
>>>>> sure.
>>>>> Paul
>>>>> WB8TSL
>>>>> 
>>>>>> On Sun, Jan 10, 2016 at 4:31 PM, Rob Sherwood. <rob at nc0b.com> wrote:
>>>>>> 
>>>>>> Paul,
>>>>>> 
>>>>>> Your last paragraph was a hoot. A ham friend of mine recently rented a
>>>>>> storage shed to keep all his spare test equipment and parts units.
>> Another
>>>>>> ham friend used to have four storage units to store all his "stuff".
>> The
>>>>>> disease is not curable with either time or antibiotics.
>>>>>> 
>>>>>> My XYL will have to deal with two homes with labs and ham shacks, 7
>>>>>> towers, 13 yagis, etc. when I am SK. Need I say more.
>>>>>> 
>>>>>> Rob
>>>>>> NC0B
>>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of
>> paul swed
>>>>>> Sent: Sunday, January 10, 2016 1:56 PM
>>>>>> To: Discussion of precise time and frequency measurement
>>>>>> Subject: Re: [time-nuts] New Member + Basic Questions
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> Nathan,
>>>>>> Bob shared a link for the Lucent units and a great amount of detail
>> has
>>>>>> been shared on Time-nuts about them. They will do what you want. The
>> Ref0
>>>>>> requires a external GPS receiver and another Time-Nuts Arduino. It
>> works
>>>>>> really well and the quality of the ref0 seems to be that of the 1pps
>>>>>> feeding it.
>>>>>> But they also make a no brainer pair that has a ref0 and ref1 that
>> has a
>>>>>> built in GPS receiver. They were $175 but they go all over the place
>> in
>>>>>> price. But it does just work.
>>>>>> Trace-ability is an interesting word around this group. From your
>>>>>> description not sure thats really a need. Accept for the oven
>> oscillator
>>>>>> they all are great and yes even really good oven oscillators are
>> great and
>>>>>> can actually be amazing. Not cheap at all though.
>>>>>> You describe your counter and sig gen they have a resolution of .1Hz
>> so
>>>>>> going further isn't really all that helpful.
>>>>>> Now here is the real issue you face and its far more of an issue then
>> you
>>>>>> expect.
>>>>>> First the generator and oscillator and suddenly you find yourself
>>>>>> acquiring more stuff. Maybe a RB, then a Cesium, distribution
>> amplifiers,
>>>>>> better antennas. Sound familiar? You are doooomed. Back away real
>> fast.
>>>>>> Good luck
>>>>>> Paul
>>>>>> WB8TSL
>>>>>> 
>>>>>>> On Sun, Jan 10, 2016 at 2:42 PM, Bob Camp <kb8tq at n1k.org> wrote:
>>>>>>> 
>>>>>>> Hi
>>>>>>> 
>>>>>>>> On Jan 10, 2016, at 1:25 PM, Nathan Johnson <jdownj at gmail.com>
>> wrote:
>>>>>>>> 
>>>>>>>> Hello All,
>>>>>>>> I'm a ham radio operator, for just a few years, and electronics nut
>>>>>>>> for
>>>>>>> many
>>>>>>>> more. I have been reading the archives and trying to learn a bit. I
>>>>>>>> am
>>>>>>> wanting
>>>>>>>> to develop an accurate frequency standard for "lab" and radio use. I
>>>>>>>> see
>>>>>>> that I
>>>>>>>> have 3 basic options that are possible on my budget, a decent
>>>>>>>> OCXO-based
>>>>>>> device,
>>>>>>>> a rubidium standard, and a GPSDO. My current uses are to supply
>>>>>>>> accurate
>>>>>>> timing
>>>>>>>> to a signal generator(not yet purchased, HP 8640/8650-something) and
>>>>>>>> a
>>>>>>> frequency
>>>>>>>> counter(Fluke 1953), mostly used in aligning radios.
>>>>>>>> In the near future I am hoping to expand that to a homebrew HF
>>>>>>>> transceiver(probably clocking a DDS chip of some sort), and some
>>>>>>>> higher frequency(possibly up to 10GHz) transverters.
>>>>>>>> So what I have learned so far about each option:
>>>>>>>> -OCXO is probably stable enough for what I am trying to do, but by
>>>>>>>> itself provides no guarantee of absolute accuracy(I'm looking at the
>>>>>>>> microwave operators "weapon of choice", the Isotemp 134-10), has an
>>>>>>>> adjustment pin
>>>>>>> for a
>>>>>>>> tuning voltage, but no idea what an appropriate value is for that
>>>>>>>> voltage without access to a more accurate standard. I will probably
>>>>>>>> build an
>>>>>>> OCXO device
>>>>>>>> of some kind anyway as an interim measure while I earn for the money
>>>>>>>> to
>>>>>>> obtain
>>>>>>>> something better, and to validate a distribution amp within the lab
>>>>>> etc.
>>>>>>>> -Rubidium Standard seems like a very nice idea, but it's still not
>>>>>>> traceable in
>>>>>>>> terms of absolute accuracy(although the adjustment range of the
>>>>>>>> available standards appears to be several orders of magnitude better
>>>>>>>> than I am
>>>>>>> likely to
>>>>>>>> need). The available standards are being re-imported from China,
>>>>>>>> with
>>>>>>> unknown
>>>>>>>> hours or life remaining, and in some cases unknown condition. They
>>>>>>> appear to be
>>>>>>>> power hogs. A $200 gamble.
>>>>>>>> -GPSDOs have many options available, and are referenced to primary
>>>>>>> standards.
>>>>>>>> Pretty sure this is where I want to go. I'm looking at Item#
>>>>>>> 231803015799 on the
>>>>>>>> usual auction site, and this seems to be everything I need? I also
>>>>>>> looked at
>>>>>>>> item# 111514491254, but there doesn't seem to be any documentation
>>>>>>>> about
>>>>>>> what's
>>>>>>>> inside.
>>>>>>> 
>>>>>>> The first item you reference is a Nortel GPSTM with all the “stuff”
>> to
>>>>>>> make it work other than the power supply. If you dig into the
>>>>>>> archives, there is a *lot* of information on them there.
>>>>>>> 
>>>>>>> The second item is a Chinese Ham built GPSDO without the antenna. It
>>>>>>> has the nice feature of being actively developed. If you can read
>>>>>>> Chinese, you can tune in to the lists that have information on it.
>>>>>>> 
>>>>>>> Of the two, I’d go for the first one from a US seller that I’ve had
>>>>>>> good luck with.
>>>>>>> 
>>>>>>> A somewhat more “do it yourself” option is:
>> http://www.ebay.com/itm/221852021307?_trksid=p2055119.m1438.l2649&ssPa
>>>>>>> geName=STRK%3AMEBIDX%3AIT
>>>>>>> 
>>>>>>> combined with a GPS receiver board. They also are available in a “2
>>>>>>> for a bit less” form from the same seller.
>>>>>>> 
>>>>>>> Each item has it’s plusses and minuses. The third item has a pretty
>>>>>>> clean
>>>>>>> 15 MHz output for microwave use.
>>>>>>> All of the 10 MHz outputs are a bit dirty noise wise if you decide to
>>>>>>> multiply them up to > 10 GHz. The normal approach in that case is to
>>>>>>> lock up a clean 100 to 150 MHz range VCXO to the GPSDO and then
>>>>>>> multiply the VCXO output to microwaves.
>>>>>>> 
>>>>>>> All of them are quite adequate to supply a reference to a signal
>>>>>>> generator or a counter. All are good enough for normal HF radio use.
>>>>>>> 
>>>>>>> Bob
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>> Am I missing key points here? Or am I headed on the right path?
>>>>>>> Appriciate any
>>>>>>>> and all input.
>>>>>>>> Nathan KK4REY
>>>>>>>> 
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