[time-nuts] New Member + Basic Questions

Rob Sherwood. rob at nc0b.com
Mon Jan 11 15:54:49 EST 2016


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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