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K3S XREF GPSDO recommendation needed

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K3S XREF GPSDO recommendation needed

Dear Gang:
A shiny new K3S has joined my Elecraft herd, though K3 #2545 is still going strong. I have been getting confused looking at GPSDOs, and wonder if someone can recommend a plug and play (or close as practicable) GPSDO for me to buy.
73 Eric WD6DBM

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Joe DeVincentis

Re: K3S XREF GPSDO recommendation needed

I have have this one and no complaints:

https://v3.airspy.us/product/lb-gpsdo-1/

73,
Joe, KO8V

> On Jun 5, 2018, at 12:08 AM, eric norris via Elecraft <[hidden email]> wrote:
>
> Dear Gang:
> A shiny new K3S has joined my Elecraft herd, though K3 #2545 is still going strong. I have been getting confused looking at GPSDOs, and wonder if someone can recommend a plug and play (or close as practicable) GPSDO for me to buy.
> 73 Eric WD6DBM
>
>

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ke9uw

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Elecraft mailing list

I bought one of these similar with the clock and freq displayed. Very handy clock.
https://www.ebay.com/itm/Latest-10MHZ-SINE-WAVE-Sinewave-GPS-DISCiPLINED-CLOCK-GPSDO-with-LCD-Display-/202153437548?hash=item2f1148a96c

Amateur Radio, KE9UW

________________________________________
From: [hidden email] [[hidden email]] on behalf of eric norris via Elecraft [[hidden email]]
Sent: Monday, June 04, 2018 11:08 PM
To: [hidden email]
Subject: [Elecraft] K3S XREF GPSDO recommendation needed

Dear Gang:
A shiny new K3S has joined my Elecraft herd, though K3 #2545 is still going strong. I have been getting confused looking at GPSDOs, and wonder if someone can recommend a plug and play (or close as practicable) GPSDO for me to buy.
73 Eric WD6DBM

Sent from Yahoo Mail on Android
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Chuck, KE9UW

Wes Stewart-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Joe DeVincentis

I'm using it for other purposes but I have one of these and it's fine.

The only downside is the very clunky software and the sometimes difficulty of
getting the two frequencies out that you might want. For 10MHz only, it's a
piece of cake.

Wes N7WS

On 6/5/2018 4:49 AM, Joe DeVincentis wrote:

> I have have this one and no complaints:
>
> https://v3.airspy.us/product/lb-gpsdo-1/
>
> 73,
> Joe, KO8V
>
>> On Jun 5, 2018, at 12:08 AM, eric norris via Elecraft <[hidden email]> wrote:
>>
>> Dear Gang:
>> A shiny new K3S has joined my Elecraft herd, though K3 #2545 is still going strong. I have been getting confused looking at GPSDOs, and wonder if someone can recommend a plug and play (or close as practicable) GPSDO for me to buy.
>> 73 Eric WD6DBM
>>
>>
> ______________________________________________________________
> Elecraft mailing list
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David Box-2

Re: K3S XREF GPSDO recommendation needed

David Box-2

Re: K3S XREF GPSDO recommendation needed

David Box-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Wes Stewart-2

Grant Youngman-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by David Box-2

I’ve been using one in the station for a long time (starting years ago before the K3 came along). Started with an HP Z3801, and replaced that with an HP Z3816, when the 3801 went to heaven. I currently use a bit more modern (and more compact) Trumble Thunderbolt. All of those have worked fine.

If I needed a new one, I’d probably buy the Bodner since it’s compact, appears to be a well regarded device, and will run off the station 12V DC supply. These are available in the US from Airspy (and maybe others) at https://v3.airspy.us/product/lb-gpsdo-1/ <https://v3.airspy.us/product/lb-gpsdo-1/>

Grant NQ5T
K3 #2091, KX3 #8342

> On Jun 5, 2018, at 10:04 AM, David Box <[hidden email]> wrote:
>
>
> ______________________________________________________________
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David Box-2

Fwd: Re: K3S XREF GPSDO recommendation needed

In reply to this post by David Box-2

Edward R Cole

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Elecraft mailing list

I do not use a GPSDO for 10-MHz reference source. Instead I bought a
Russian surplus OCXO from e-bay for $40:
http://www.kl7uw.com/K3EXREF.htm was my beta-tester report
http://www.kl7uw.com/Rubidium.htm more info on OCXO install. I
stopped using a "wall-wart" for 12v supply after discovering excess
ripple from the "wart". Now I simply use my station Astron 50 which runs 24/7.

For GPS time I use a little GPS dongle (plugs into computer USB
jack). Model BU-363 found on e-bay for about $15. I run BktTime
(IZ2BKT) sw to control computer time (previously used
Dimension-4). This keeps my computer time accurate for running JT65.

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

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David Box-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Elecraft mailing list

I have one of Bodnar's units and works well. The software is clunky but
usable. There is a way to set other frequencies than what the pulldown
menus offer. You need to go to and download a copy of the DSPLLsim
utility in order to calculate the correct coefficients..

Below is a set of steps that Jan Verduyn has published that allows
setting the two ports to other frequencies, in this case he was trying
to get 10Mhz and 36MHz but using DSPLLsim you can work out other pairs.
DSPLLsim is at
<https://www.silabs.com/products/development-tools/software/clock>

If you only need one frequency then Bodnar also sells a smaller unit
<http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=301>
that is lower priced. AirSpy also sells this unit.

Dave K5MWR

From Jan Verduyn instructions for tailoring frequencies.

Setting of the GPSDO Output 1 to 10MHz and GPSDO Output 2 to 36.000 MHz
as external clock for the VNWA is done as follows:

Start the GPS clock application for the Leo Bodnar standard 2 port GPSDO.

1. Set output 1 and output 2 to 10000000 Hz = (10 MHz)

2. Make sure both outputs are enabled

3. Press “Find” and both output should be locked and produce 10.000 MHz

4. Now change the register details as shown below by typing in the
following data:

10000000 = GPS Reference Hz

5 = N31

6 = N2_HS

450 = N2_LS

5 = N1_HS

108 = NC1_LS

30 = NC2_LS

0 = Phaseshift degrees (unchanged)

15 = BW unchanged

5. next press “Update” button and both outputs should show red – locked

6. If you measure with Frequency meter you will find that output 1
produces 10 MHz and Output 2 will produce 36 MHz.

Note that the output 2 indication will continue to show 10 MHz, which is
wrong. It should read 36MHz.

These settings are stored when you switch off the GPSDO, When you apply
power to GPSDO at a later date the same frequencies should be produced.

Remember however as soon as you press the “Find button” the settings
will be lost and will need to be re-entered.

If GPS Signals are lost then the output frequencies are derived from the
built-in TCXO with the last correction factor applied before lock was lost.

The above register settings were obtained using DSPLLsim utility.
Make sure you select the SI5328 to obtain the correct settings.

Attached is a screenshot of the GPS Clock Configuration screen.

Good luck.

Jan G5BBL SDR-Kits

On 6/5/2018 7:38 AM, Wes Stewart wrote:
> I'm using it for other purposes but I have one of these and it's fine.
>
> The only downside is the very clunky software and the sometimes
difficulty of getting the two frequencies out that you might want. For
10MHz only, it's a piece of cake.
>
> Wes N7WS
>
> On 6/5/2018 4:49 AM, Joe DeVincentis wrote:
>> I have have this one and no complaints:
>>
>> https://v3.airspy.us/product/lb-gpsdo-1/
>>
>> 73,
>> Joe, KO8V
>>
>>> On Jun 5, 2018, at 12:08 AM, eric norris via Elecraft
<[hidden email]> wrote:
>>>
>>> Dear Gang:
>>> A shiny new K3S has joined my Elecraft herd, though K3 #2545 is
still going strong. I have been getting confused looking at GPSDOs, and
wonder if someone can recommend a plug and play (or close as
practicable) GPSDO for me to buy.
>>> 73 Eric WD6DBM
>>>
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>
> ______________________________________________________________
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Clay Autery-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Joe DeVincentis

Eric,

Joe's link is to the 2-output Bodnar unit I recommended to you in my
private response to you.

AirSpy is the US source for the unit. I would do a price compare with
shipping to see if the unit ex-VAT and Royal Mail from Bodnar or
SDR-Kits is more or less than the US price + shipping from AirSpy.

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/05/18 06:49, Joe DeVincentis wrote:

Clay Autery-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Wes Stewart-2

The software COULD be better. I needed 36 MHz and 10 MHz and that
wasn't "available" directly in the software, but with the right manual
parameter settings, you can achieve virtually ANY combination.
I believe Wes, you were the one that clued me in to this fact..... as
well as the multiple parameter combination to achieve the same output
freq combos.

As you said.... 10 MHz only... easy-peasey.

Question that will save me a lot of research.... Can the Bodnar be fed
to the K3s directly bu jumper without attenuation? Just verifying.
Don't want to feed too high a signal and torch something. :)

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/05/18 07:38, Wes Stewart wrote:

> I'm using it for other purposes but I have one of these and it's fine.
>
> The only downside is the very clunky software and the sometimes
> difficulty of getting the two frequencies out that you might want.
> For 10MHz only, it's a piece of cake.
>
> Wes N7WS
>
> On 6/5/2018 4:49 AM, Joe DeVincentis wrote:
>> I have have this one and no complaints:
>>
>> https://v3.airspy.us/product/lb-gpsdo-1/
>>
>> 73,
>> Joe, KO8V
>>
>>> On Jun 5, 2018, at 12:08 AM, eric norris via Elecraft
>>> <[hidden email]> wrote:
>>>
>>> Dear Gang:
>>> A shiny new K3S has joined my Elecraft herd, though K3 #2545 is
>>> still going strong. I have been getting confused looking at GPSDOs,
>>> and wonder if someone can recommend a plug and play (or close as
>>> practicable) GPSDO for me to buy.
>>> 73 Eric WD6DBM
>>>
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>
> ______________________________________________________________
> Elecraft mailing list
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>
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Grant Youngman-2

Re: K3S XREF GPSDO recommendation needed

My Trimble Thunderbolt puts out +7 dBm. The Bodnar can be set for +13-something down to +7.7 dBm. Sounds in the ballpark.

The Trimble hasn’t torched anything. I don’t recall seeing specs on maximum input power for the K3 but I haven't looked at it for a while, have a short memory, and they’re probably there somewhere in the paperwork …

Grant NQ5T
K3 #2091, KX3 #8342

> Can the Bodnar be fed to the K3s directly bu jumper without attenuation? Just verifying. Don't want to feed too high a signal and torch something. :)
>

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Clay Autery-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Grant Youngman-2

While the Bodnar GPSDO will run off "station power" as long as it sees
less than 14 vdc at the external DC (5.5mm x 2.1mm (+ to center pin)
connector, anything above 5 vdc is dumped as heat into that tiny little
chassis.

It will ALSO run fine (and preferred) at 5 volts DC from EITHER the USB
port OR the External power connector.

Here is what I do:

1) I don't have the GPSDO connected to the computer via USB when I am
not ACTUALLY setting it via software.

2) I can run it from a USB cable connected to a "charge only" port on my
computer connected hub OR from ANY port on the USB hub I use for "power
only" and no connection to a computer. BOTH of these hubs have 12 VDC
external power supplied STOCK by a 12 vdc switching PS (wall wart). "I"
power them from the station power supply (13.9 VDC) via an LM317 based
adjustable DC regulator that I set at precisely 12 VDC.

3) Alternatively, I can power the GPSDO via the Ext Power connector with
5 VDC from EITHER a USB cable hacked on one end to add the 5.5mm x 2.1mm
connector (to the aforementioned USB hubs), OR via a twisted pair cable
with 5.5mm x 2.1mm connector on one and and the other end terminated to
connect to the 5VDC output of the regulator I mentioned earlier that
primarily powers the HP 58516a GPS Antenna Splitter/amp.

Bottom line... I eliminated the switching supplies from the picture and
feed the GPSDO 5vdc to minimize the waste heat dumped into the GPSDO
chassis.

As an aside, and verified with Leo Bodnar, you can switch the GPSDO from
computer connected to power ONLY WITHOUT cold booting the device (you do
not have to power it down). With the unit connected to the computer via
USB, simply connect some other 5vdc power source to the Ext Power
connector (USB or other as described above) You now have 5 vdc going to
both USB and Ext Pwr connectors. THEN, disconnect the USB connection to
the computer. The unit is now on EXTERNAL DC only, no data/computer
connection.

I then perform an additional step... I plug a pwer only connection BACK
into the USB connector (to a charging-only or a power-only USB hub/power
bus), and then remove the power cable from the Ext Pwr connector.

Why? To remove the possibility that the computer connection might feed
something back into the GPSDO and affect its frequency outputs.

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/05/18 09:31, Grant Youngman wrote:

> I’ve been using one in the station for a long time (starting years ago before the K3 came along). Started with an HP Z3801, and replaced that with an HP Z3816, when the 3801 went to heaven. I currently use a bit more modern (and more compact) Trumble Thunderbolt. All of those have worked fine.
>
> If I needed a new one, I’d probably buy the Bodner since it’s compact, appears to be a well regarded device, and will run off the station 12V DC supply. These are available in the US from Airspy (and maybe others) at https://v3.airspy.us/product/lb-gpsdo-1/ <https://v3.airspy.us/product/lb-gpsdo-1/>
>
> Grant NQ5T
> K3 #2091, KX3 #8342
>
>> On Jun 5, 2018, at 10:04 AM, David Box <[hidden email]> wrote:
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
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> Message delivered to [hidden email]

Clay Autery-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Edward R Cole

Just curious... Why would you choose NOT to discipline the OXCO?

And I agree.... wall warts, and indeed ALL switching supplies are the
work of Satan. <wink>

I have/am eliminated/ing everyone I can.

I don't have a device with an OXCO yet, but I am powering my TXCO GPSDO
from Bodnar with a VERY quiet linear DC supply. (Astron Linear with
additional outboard regulation and filtering).

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/05/18 10:53, Edward R Cole wrote:

> I do not use a GPSDO for 10-MHz reference source. Instead I bought a
> Russian surplus OCXO from e-bay for $40:
> http://www.kl7uw.com/K3EXREF.htm was my beta-tester report
> http://www.kl7uw.com/Rubidium.htm more info on OCXO install. I
> stopped using a "wall-wart" for 12v supply after discovering excess
> ripple from the "wart". Now I simply use my station Astron 50 which
> runs 24/7.
>
> For GPS time I use a little GPS dongle (plugs into computer USB
> jack). Model BU-363 found on e-bay for about $15. I run BktTime
> (IZ2BKT) sw to control computer time (previously used Dimension-4).
> This keeps my computer time accurate for running JT65.
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> Dubus-NA Business mail:
> [hidden email]
>

Clay Autery-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by David Box-2

Here is a copy/paste of the post I made on the VNWA Group for a summary
of the two methods I've seen for setting 36MHz and 10 MHz just for the
record:
Other combinations would require the use of the SilLabs software to
calculate the parameters.... I have yet to figure out how to use it
correctly. But there are those who have and MAY be amenable to
calculating them for you.
____________________________________________________

Here are TWO methods for setting 36MHZ and 10MHZ together:

Method #1: Output #1 = 10MHz; Output #2 = 36MHz (Thank you, Jan!)

Start GPS Clock Configuration application

1. Set Outputs 1 & 2 (Hz) to 10000000 (10 MHz) AND "Output Drive
Strength" to 8mA.

2. Make sure both output enable boxes are checked.

3. Press “Find”. When complete, both outputs lock at 10000000 Hz.(10MHz)
4. Now, enter the following register values:
____________________________

10000000 = GPS Reference Hz

5         = N31

6         = N2_HS

450       = N2_LS

5         = N1_HS

108       = NC1_LS

30        = NC2_LS

0         = Phase shift degrees (unchanged)

15        = BW (unchanged)
____________________________

5. Click "Update". When finished, both will show 10000000 MHz, BUT wait!

7. Close the GPS Clock Configuration app. Then restart the app. The
displays will update to reflect 10 MHz on Out #1 and 36MHz on Out #2.
You can confirm this by measuring them with a frequency counter/meter.

DO NOT PRESS "Find"! If you do, you will set both to 10MHz and have to
start all over.

++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++

Method #2: Output #1 = 36MHz; Output #2 = 10MHz (Thanks to Simon @ Bodnar)

Start GPS Clock Configuration application

1. Set Output 1 (Hz) to 36000000 (36 MHz) and "Output Drive Strength" to
8mA.

2. Make sure both output enable boxes are checked.

3. Press “Find”. When complete, both outputs lock at 36000000 Hz.(36MHz)
4. Now, enter the following register values:
____________________________

4800000 = GPS Reference Hz

11        = N31

11        = N2_HS

1350      = N2_LS

9         = N1_HS

20        = NC1_LS

72        = NC2_LS

0         = Phase shift degrees (unchanged)

15        = BW (unchanged)
____________________________

5. Click "Update". When finished, both MAY show 36000000 MHz, mine
displays correctly about a third of the time. BUT as before... wait!

7. Close the GPS Clock Configuration app. Then restart the app. The
displays will update to reflect 36 MHz on Out #1 and 10 MHz on Out #2.
You can confirm this by measuring them with a frequency counter/meter.

DO NOT PRESS "Find"! If you do, you will set both to 10MHz and have to
start all over.

Here is an image to illustrate the results:
http://www.montac.com/images/vnwa/36x10Mhz_Bodnar.jpg

================================

NOTE: You can tell the "Find" or "Update" process is complete when ALL
three labels ("Find", "Update", and "Sleep") are NOT "greyed out. Text
is black.

I've not yet confirmed whether 8mA is sufficient drive current to feed
10 MHz to my HP5335a or Elecraft K3s, et al. yet. When I do, I will
post back with results.

Hope y'all find this useful!

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/05/18 12:48, David Box wrote:

>
>
> I have one of Bodnar's units and works well. The software is clunky
> but usable. There is a way to set other frequencies than what the
> pulldown menus offer. You need to go to and download a copy of the
> DSPLLsim utility in order to calculate the correct coefficients..
>
> Below is a set of steps that Jan Verduyn has published that allows
> setting the two ports to other frequencies, in this case he was trying
> to get 10Mhz and 36MHz but using DSPLLsim you can work out other
> pairs. DSPLLsim is at
> <https://www.silabs.com/products/development-tools/software/clock>
>
>
> If you only need one frequency then Bodnar also sells a smaller unit
> <http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=301>
> that is lower priced. AirSpy also sells this unit.
>
> Dave K5MWR
>
>
> From Jan Verduyn instructions for tailoring frequencies.
>
> Setting of the GPSDO Output 1 to 10MHz and GPSDO Output 2 to 36.000
> MHz as external clock for the VNWA is done as follows:
>
>
>
> Start the GPS clock application for the Leo Bodnar standard 2 port GPSDO.
>
>
>
> 1. Set output 1 and output 2 to 10000000 Hz    = (10 MHz)
>
> 2. Make sure both outputs are enabled
>
> 3. Press “Find” and both output should be locked and produce 10.000 MHz
>
> 4. Now change the register details as shown below by typing in the
> following data:
>
>
>
> 10000000   = GPS Reference Hz
>
> 5                   = N31
>
> 6                   = N2_HS
>
> 450              = N2_LS
>
> 5                   = N1_HS
>
> 108              = NC1_LS
>
> 30                = NC2_LS
>
> 0                           = Phaseshift degrees (unchanged)
>
> 15                       = BW unchanged
>
>
>
> 5. next press “Update” button and both outputs should show red – locked
>
> 6. If you measure with Frequency meter you will find that output 1
> produces 10 MHz and Output 2 will produce 36 MHz.
>
>
>
> Note that the output 2 indication will continue to show 10 MHz, which
> is wrong. It should read 36MHz.
>
> These settings are stored when you switch off the GPSDO, When you
> apply power to GPSDO at a later date the same frequencies should be
> produced.
>
> Remember however as soon as you press the “Find button” the settings
> will be lost and will need to be re-entered.
>
> If GPS Signals are lost then the output frequencies are derived from
> the built-in TCXO with the last correction factor applied before lock
> was lost.
>
> The above register settings were obtained using DSPLLsim utility. Make
> sure you select the SI5328 to obtain the correct settings.
>
>
>
> Attached is a screenshot of the GPS Clock Configuration screen.
>
> Good luck.
>
>
>
> Jan G5BBL SDR-Kits

Elecraft mailing list

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Grant Youngman-2

The spec's are in the K3EXREF manual I have dated August 2016,
Rev B. page 4

"Connect the external 10 MHz signal source to the rear panel
REF. connector. The 10 MHz source should have a signal level
between +4 dBm and +16 dBm, nominal. For square wave sources,
2VDC to 3.3VDC peak is optimum. If the source is a 5V logic
level, use a 50-ohm resistor in series with the input.
Caution: To avoid damage to the K3EXREF, do not exceed these
levels."

73,
Bob
K2TK ex KN2TKR (1956) & K2TKR

On 6/5/2018 3:31 PM, Grant Youngman wrote:
> My Trimble Thunderbolt puts out +7 dBm. The Bodnar can be set for +13-something down to +7.7 dBm. Sounds in the ballpark.
>
> The Trimble hasn’t torched anything. I don’t recall seeing specs on maximum input power for the K3 but I haven't looked at it for a while, have a short memory, and they’re probably there somewhere in the paperwork …
>
>
> Grant NQ5T
> K3 #2091, KX3 #8342
>
>> Can the Bodnar be fed to the K3s directly bu jumper without attenuation? Just verifying. Don't want to feed too high a signal and torch something. :)

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Clay Autery-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Grant Youngman-2

Found this in the K3EXREF manual:

"Connect the external 10 MHz signal source to the K3 rear panel REF.
connector. The 10 MHz source
should have a signal level between +4 dBm and +16 dBm, nominal. For
square wave sources, 2VDC to
3.3VDC peak is optimum. If the source is a 5V logic level, use a 50-ohm
resistor in series with the
input. Caution: To avoid damage to the K3EXREF, do not exceed these levels."

So, it would appear that the +8dBm setting I have set as per the VNWA
directions for 36 MHz, will work in that respect for the K3s.

As I understand it, the Bodnar unit is square-wave, so the only question
is what is the voltage envelope for the signal?
I STILL am awaiting my crimper to match my cable stock, so I can't make
a BNC to SMA cable to test the Bodnar output.

The DC voltage on the output from my non-RMS multimeter is about 1.589
VDC, so that would indicate 2 x 1.589 = 3.178 approx. pk-pk, right?

This agrees with the Bodnar site which says: "Both output signals are at
3.3V CMOS levels with 50 Ohms characteristic impedance."

Thus, my conclusion would be direct connection via jumper wire only; no
attenuation, et al. required.

Thanks! It was easier to research than I thought. <blush>

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/05/18 14:31, Grant Youngman wrote:

> My Trimble Thunderbolt puts out +7 dBm. The Bodnar can be set for
> +13-something down to +7.7 dBm. Sounds in the ballpark.
>
> The Trimble hasn’t torched anything. I don’t recall seeing specs on
> maximum input power for the K3 but I haven't looked at it for a while,
> have a short memory, and they’re probably there somewhere in the
> paperwork …
>
>
> Grant NQ5T
> K3 #2091, KX3 #8342
>
>> Can the Bodnar be fed to the K3s directly bu jumper without
>> attenuation? Just verifying. Don't want to feed too high a signal
>> and torch something. :)
>>
>

Wes Stewart-2

Re: K3S XREF GPSDO recommendation needed

In reply to this post by Clay Autery-2

I'm not answering for Ed, and I don't have the Ref Lock doodad for my K3.

That said, a decent OCXO, like a Morion, will have, after warm up and a little
aging, stability more than adequate to discipline a K3. The K3 isn't phase
locked to an external reference anyway, it's just "nudged" on frequency
periodically.

If GPS lock is lost on the Bodnar device it reverts to a TCXO that is likely no
better than the one in the K3, assuming the high stability option. (Note: I
haven't pursued all of the relevant specs, this is just gut feel.)

I have the Bodnar unit because my sweetie asked me what I wanted for Christmas a
few years ago and I had just read about it. I have no compelling need, but I
did use it with a modified SDR-IQ to try my hand at the last ARRL FMT. I also
have a Morion, off eBay, that I thought I should have. I have yet to apply
power to it :-) I suppose I was remembering the days when I would have killed
to have something that accurate.

Likewise after reading timenuts I thought I should get a TAPR GPS time standard
kit. I have absolutely no need for that either but Lady Heather looks nice on a
spare computer screen ticking away at one second increments with nanosecond
accuracy :-).

Wes N7WS

On 6/5/2018 12:55 PM, Clay Autery wrote:

> Just curious... Why would you choose NOT to discipline the OXCO?
>
> And I agree.... wall warts, and indeed ALL switching supplies are the work of
> Satan. <wink>
>
> I have/am eliminated/ing everyone I can.
>
> I don't have a device with an OXCO yet, but I am powering my TXCO GPSDO from
> Bodnar with a VERY quiet linear DC supply. (Astron Linear with additional
> outboard regulation and filtering).
>
> 73,
>
> ______________________
> Clay Autery, KY5G
> (318) 518-1389
>
> On 06/05/18 10:53, Edward R Cole wrote:
>> I do not use a GPSDO for 10-MHz reference source. Instead I bought a Russian
>> surplus OCXO from e-bay for $40:
>> http://www.kl7uw.com/K3EXREF.htm was my beta-tester report
>> http://www.kl7uw.com/Rubidium.htm more info on OCXO install. I stopped using
>> a "wall-wart" for 12v supply after discovering excess ripple from the
>> "wart". Now I simply use my station Astron 50 which runs 24/7.
>>
>> For GPS time I use a little GPS dongle (plugs into computer USB jack). Model
>> BU-363 found on e-bay for about $15. I run BktTime (IZ2BKT) sw to control
>> computer time (previously used Dimension-4). This keeps my computer time
>> accurate for running JT65.
>>
>> 73, Ed - KL7UW
>> http://www.kl7uw.com
>> Dubus-NA Business mail:
>> [hidden email]
>>
>
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