[time-nuts] New Member + Basic Questions

Scott McGrath scmcgrath at gmail.com
Fri Jan 15 08:11:21 EST 2016


The 8660 is really a sweep generator designed for alignment of IF stages of airband and satellite gear.  Hence its odd frequency selections and it's miserable phase noise performance that being said I have a couple of them and the are good generators for  general purpose use if you respect their limitations



Content by Scott
Typos by Siri

> On Jan 15, 2016, at 12:58 AM, Rob Sherwood. <rob at nc0b.com> wrote:
> 
> 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
>>>>>>>>> 
>>>>>>>>> Sent using CloudMagic Email
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>>> https://cloudmagic.com/k/d/mailapp?ct=pi&cv=7.4.15&pv=9.1&source=email
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>>>>>>>> ]
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