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RE: External 10MHz clock

K3ROJ — Sun, 31 Oct 2010 07:23:01 GMT

[quote][b]va3qr (8/30/2010)[/b][hr]So I got my Flex 5KA last Friday afternoon. Not wanting to be left wondering if I should have a 10MHz reference or not, I hopped on eBay and purchased a Thunderbolt GPS Timing Sensor used from China. The kit came with the sensor, power supply, external antenna with 30' of coax and DB9 serial cable.

I downloaded the setup program from the web after Googling around for about 5 minutes, turned it on and, within about 10 minutes, the software was reporting 10MHz accuracy at +/- 0.06ppb.

I use HF mainly, but I figured it was listed for under $200USD after shipping and I'm getting the VHF/UHF upgrade as SOON as its available so I might as well be on the safe side and set it up.

Just throwing in my 2 cents.[/quote]

Using a GPS 10 MHz reference is the best idea and you can either make or buy a distribution box to supply 10 MHz to other radios or projects using regular RG6 coax. JWM Engineering and KUHNE Electronics have available many PLL oscillators used for beacons or to replace older crystal oscillators such is in my Elecraft XV144 transverter (116 MHz). I have a low power referenced oscillator made by JWM Engineering on 1296 MHz where I can quickly check to see if my station is receiving OK. It is always great to know my Flex5000A and 1500 are precisely on frequency each time they are turned on.

RE: External 10MHz clock

va3qr — Mon, 30 Aug 2010 15:54:39 GMT

So I got my Flex 5KA last Friday afternoon. Not wanting to be left wondering if I should have a 10MHz reference or not, I hopped on eBay and purchased a Thunderbolt GPS Timing Sensor used from China. The kit came with the sensor, power supply, external antenna with 30' of coax and DB9 serial cable.

I downloaded the setup program from the web after Googling around for about 5 minutes, turned it on and, within about 10 minutes, the software was reporting 10MHz accuracy at +/- 0.06ppb.

I use HF mainly, but I figured it was listed for under $200USD after shipping and I'm getting the VHF/UHF upgrade as SOON as its available so I might as well be on the safe side and set it up.

Just throwing in my 2 cents.

RE: External 10MHz clock

HowardZ — Wed, 09 Jun 2010 22:59:54 GMT

I have noticed that NAVSYNC's website specifies the 1pps signal's accuracy as 30ns, but does not specify the 10Mhz signal's accuracy.

I emailed NAVSYNC asking what the 10Mhz signal's accuracy is. I got this answer:

"with a 3D GPS fix the accuracy of the frequency output is typically 0.5 ppb (or 0.0005 ppm)."

So, I think the CW46 offers a good value, as there is no Rubidium to wear out.
One can afford to buy a new one, rather than a used one.
It is easy to integrate to the Flex 5000, one only needs a SMA to BNC adapter.
One also has to hook the two power wires (too short in my opinion) to your power supply.

P.S. Chris, so far I have tried using FLDIGI to listen to WWV at 10Mhz. I reduce the frequency by 1Khz because FLDIGI's frequency measurement function listens at 1Khz above dial frequency. The CW46 seems to read the WWV within 1 HZ. Occasionally it will show between 1HZ and 2HZ off. I do not know how accurate FLDIGI's frequency measurement function is.

RE: External 10MHz clock

ZL1BOE — Wed, 09 Jun 2010 22:58:46 GMT

Hi Howard,

Just as a matter of interest, if you were to use your Flex to measure an unknown frequency with great accuracy how would you do it? The PowerSDR display only resolves to 1Hz I think.

Would one need external software?

In the Winrad SDR software the ECSS modulation mode (Synchronous AM) actually takes charge of the frequency display and reads out the carrier frequency being received - but only resolves to 1Hz. Not sure if the PowerSDR software SAM mode works like Winrd ECSS 0 - in the sense that the display automatically shows the the measured frequency? However it would take better than 1Hz resolution to win a competition these days. Of course propagation takes it's toll on measurements also.

I participate in local frequency measurement competitions here in ZL and have had some success using a conventional RX plus MixW software which resolves to 0.1Hz. But more digits will be needed to take advantage of a GPS or rubidium clock.

73, Chris

RE: External 10MHz clock

K3ROJ — Wed, 09 Jun 2010 09:38:10 GMT

I believe the best 10 MHz reference device is the Z3801A which was used a few years ago at cell phone sites for precise frequency and timing control. Once in a while you will see someone on E-Bay selling several units for around $300 to $500 depending on whether or not they have been converted to use RS232 instead of their RS422 which is a simple mod using header pins. Sometimes sellers include a GPS antenna and power supply. 48 volts or more is required which can be a simple transformer/capacitor power supply since they were made to run on battery/generators during power outages. I didn't go the Rubidium route since I know at least 2 hams who's rubidium source eventually stopped working. Anyway, my Z3801A remains on 24 hours a day sitting in my basement with a small GPS antenna outside and RG6 from a splitter feeding my 5000A, HP signal generator, HP frequency generator and eventually my 1500 when it arrives. Here is a great site explaining everything you need to know about it:
http://www.realhamradio.com/GPS_Frequency_Standard.htm
My Flex 5000A is so accurate that I would be ashamed to use it in the ARRL frequency measurement tests. When I eventually get the 5000A V/U internal transverter board installed, the 5000A will become the most accurate and stable piece of test gear available and if another station also has a reference, we could work PSK31 on 432.200000 Mhz for example without having to tune each other in and just imagine working meteor scatter on 144.080000 MHz.

RE: External 10MHz clock

HowardZ — Thu, 03 Jun 2010 23:28:43 GMT

Chris,

I am happy that you introduced me to the www.navsync.com website.

I purchased the Navsync CW46 GPS Timing Sensor.
This small box has the chip you mentioned, plus a built-in GPS antenna.

It has two thin wires coming out - one is a 1pps signal and the second is a 10Mhz signal. They are SMA, so I use a SMA-Female to BNC-Male adapter.

It takes a wide voltage range, from 6.5 to 24.0 volts.

Accuracy is 30ns - a nanosecond is one billionth of a second - which I think means 30 ppb (parts per billion) accuracy.

It comes with a 9-pin RS232 COM port cable and free software called "NS3K View" so watch the GPS working.

I can see that it is available as a USB model, but I bet it just means they include a USB serial adapter.

PLUSES: No Rhibidium to wear out, and it is more accurate than the Rhibidium clock.
NEGATIVE: dependent on being able to hear at least one GPS satellite, cost more than a used Rhibidium clock from Ebay/Hong Kong

Cost: $244 plus shipping = $253

Howard

RE: External 10MHz clock

HowardZ — Tue, 25 May 2010 22:17:38 GMT

Well Chris,

I was looking at the $500 Development Kit
http://secure.conwin.com/cgi-bin/store/cp-app.cgi?usr=51H676289&rnd=8836536&rrc=N&affl=&cip=69.211.225.2&act=&aff=&pg=prod&ref=51665&cat=navsync&catstr=HOME:navsync

But, there is also a lower cost $244 item
http://secure.conwin.com/cgi-bin/store/cp-app.cgi?usr=51H676289&rnd=5438911&rrc=N&affl=&cip=&act=&aff=&pg=prod&ref=53125&cat=navsync&catstr=HOME:navsync

With this one, it appears we'd need to only make two connections - the 10Mhz cable to the Flex 5000, and to provide this unit with DC power. There is a weird connector which carries many wires - including the DC power. The unit has a built-in GPS antenna. So, I'd think people would need a 10 ft power cord and a 10 ft coax cable - to try to position it near a window.

My main concern would be the ability to buy that weird connector needed for the DC power.

I'd imagine a GPS unit will last longer than a used Rhibidium unit - as long as the government keeps GPS satellites in space.

Howard

RE: External 10MHz clock

ZL1BOE — Tue, 25 May 2010 16:57:11 GMT

Sure appreciate your advice Howard. I plan to purchase of of those rubidium units off Ebay as you suggest. As previously mentioned my interest is frequency measurement and with a Flex 1500 I should have a neat measurement reciever and signal generator!

73, Chris ZL1BOE

RE: External 10MHz clock

HowardZ — Tue, 25 May 2010 10:40:45 GMT

Hi Chris,

I looked into the unit you found. The cost is $500 for the GPS Unit - ready to go - in a nice box with all the connectors and a power supply. The cost is rather high.

The used Rhibidium clock I purchased on Ebay from China cost $80. Presumably it was used in cell phone towers to keep equipment on frequency.

Now, if a company like Flex were to buy only the GPS chip in bulk - and incorporate it into their own circuit board I am sure the cost would be very reasonable. However, the average Amateur Radio operator wouldn't want to pay for it, as 1ppm or 1/2 ppm is sufficient for most purposes. I can see 5 E10-8 being useful for VHF/UHF digital work where being exactly on frequency can be important.

I'm not sure how to do the math 5 E10-8 = 50 E10-9 = 50 ppb?
50 parts per billion?

RE: External 10MHz clock

HowardZ — Mon, 24 May 2010 13:35:46 GMT

I purchased a used Rhibidium clock from this guy on Ebay. After a few seconds it provides accuracy of 1 part per 50 million (5E-8). I only use it a few hours per day - I won't keep it on 24X7 because it is used and the Rhibidium eventually will be spent.

http://cgi.ebay.com/EFRATOM-LPRO-101-Rubidium-10MHZ-Fre-Standard-Easy-Kit-/180377137148?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item29ff50affc

Basically what the Flex 5000a needs is a 10Mhz clock to coax BNC male. The box you mentioned sounds like similar accuracy - it says 5nanoseconds. Your challenge will be programming it for 10Mhz and interfacing it to the radio and providing it a GPS antenna.

External 10MHz clock

ZL1BOE — Sun, 23 May 2010 16:15:52 GMT

Of course there are some lucky hams already out there with Rubidium (Caesium?) or GPS stabilized standards but it seem likely than many of us might be looking for a lower cost external clock solution for the Flex 5000 (and the new Flex 1500)

The Navsync CW-25TIM (http://www.navsync.com/notes3.html#2) module is a sub $70.00 module GPS stabilized standard which measures roughly 2" x 1.5" and will hold synch down to only one satellite even in-doors in most cases. All we need is someone knowledgeable to tell us if it can be direct connected to the Flex 5000/1500 clock input?

I am not presently thinking of UHF/microwave operations am very keen on frequency measurement. I have a Flex 1500 on order but in the meantime using an RFSpace SDR-IQ reciever with Winrad software in ECSS mode it is a cinch to read 15 Mhz WWV down to the last Hz. Unfortunately, unlike the Flex 5000 and 1500 the SDR-IQ does not provide for an external clock. Any one know whether Flex Power SDR SAM mode works the same way as Winrad's ECSS? i.e. phase locks onto any carrier and shows the measured frequency directly on the display?

Can anyone suggest an economical Flex 5000/1500 (sub $200) external clock solution? Even a higher quality quartz clock would be of interest.

73, Chris ZL1BOE