I have decided to make some of the external clock reference interface boards for the QDX, both the direct and the clock-multiplier versions.  Also I will have replacement QDX back-panels so we won't have to drill a new hole in the existing QDX panel.

The direct interface accepts a 25 MHz clock (from a Bodnar GPSDO, or perhaps Glenn's (N6GN) upcoming budget GPSDO.  The multiplier version includes a PLL chip that accepts a 5 or 10 MHz reference and generates the 25 MHz clock required by the QDX.  If all goes well these should be available in a couple of weeks.  See my wb6cxc.com blog for more details.





"Turn Island Systems" is my "company".  Not much going on there though -- for the moment it's just me and a friend messing around.

Another one to do the 66.66 MHz clock for the KiwiSDR would that be a good addition to the product catalogue ?
With the beautiful back-panel of course!

And Glenn n6gn creating not only a gps antenna distribution board but also a 8-port reference signal distribution board laid out for 5/10/25 MHz ?

Heaven can wait ...

Erwin

Kiwi interface?  I will look into it!  I don't have a Kiwi, but I will discuss it with Rob and Glenn.

There's another project I am working on, mainly for myself but I would be pleased if others could also use it, is a very simple clock distribution buffer.  It has one 50-Ohm input, and five 50-Ohm AC-coupled square-wave outputs.  The input range is 1-50 MHz, -10 to +20 dBm, and the outputs are 3V P-P unloaded.  The outputs are nominally phase-matched, but the in/out delay is unspecified (just device and layout delay.)  The thing is powered through a USB jack (power only).  It's probably not up to calibration-lab standards, but for basic distribution of clocks it's good enough.  I already have a 10 MHz distribution box in my garage-lab, but it's a heavy rack-mount thing and I want something I can move around.



I've also got an enclosure and front/back panels.  The board just went out for fab and assy, I should have it back in a couple of weeks.

Some of our WD sites have 7 or more Kiwis which would ideally all be GPSDO locked.  I have 6 Kiwis at KFS, 7 at KPH and 3 in Maui.

On Sat, Mar 25, 2023 at 09:03 AM, Paul WB6CXC (tech-blog: wb6cxc.com) wrote:

The input range is 1-50 MHz

I actually expect the clock distribution buffer input frequency range to be below 100 KHz to well over 100 MHz, since I've run similar input and output circuits to beyond 200 MHz, This board also has optional output transformers to provide isolated and floating outputs (minimizing ground-loops), but the first batch of boards will be stuffed for common input, output, and power ground.

On Sat, Mar 25, 2023 at 09:23 AM, Rob Robinett wrote:

Some of our WD sites have 7 or more Kiwis which would ideally all be GPSDO locked.

This is an example of why the distribution board has five outputs -- units can be reasonably daisy-chained.  With two boards you get nine outputs.  Of course if the GPSDO output is strong, and the radio reference input sensitivity is adequate then you don't need a buffer, just some splitters.  But I could probably sell the distribution boards for $50 (without the enclosure).

CMI can be an issue. Glenn made efforts to minimize that on his GPS distro board.

-Jim

WA2ZKD

On Sun, Mar 26, 2023 at 05:02 AM, Jim Lill wrote:

CMI can be an issue. Glenn made efforts to minimize that on his GPS distro board

Understood.  It's not been a real problem in my setups, but I do have some isolation transformer boards I can insert when the need arises:


And if there is demand beyond my own use for the distribution board I will probably build the isolated version.

I've mailed out a bunch of the QDX External Clock Interface boards (both the Direct 25 MHz unit, and the Multiplier (10 -> 25 MHz) unit, and I'm going to be having a second batch fabricated and assembled.  I'm running this through my previously dormant TurnIslandSystems.com website, where there is more info on the boards.  If anyone wants one please let me know so I can put you on the list.
73,
Paul / wb6cxc