Even a TCXO is not stable within the LNB!
And there is a lack of space in the LNB, it needs a lot of soldering skills to get this done.
Preferred solution is to feed the 25MHz via cable, preferred LNB has min. two outputs, use one of these to feed the 25MHz. I use a ferrite bead as a transformer as suggested somewhere in this forum.
TCXO or later GPSDO can be placed in temperated shack 
I simply use a AS169-73 (RF switch). Inputs connected to internal TCXO and a added SMA connector, output connected via 47pF to AD9363ABCZ xtalin input. Appropriate control signals generated from PS_GPIO6 for the AS169 and the TCXO enable (off while external).
Important to add 20k in parallel to R91!!! This lets the (original) FW think it is a rev. D HW and the ext clock commands will work:
// this enables the internal TCXO
fw_setenv refclk_source internal
// this enables the external CLK in
fw_setenv refclk_source external
// set different ref. clocks
fw_setenv ad936x_ext_refclk '<40000000>'
fw_setenv ad936x_ext_refclk_override '<40000000>'
fw_setenv ad936x_ext_refclk '<45000000>'
fw_setenv ad936x_ext_refclk_override '<45000000>'
fw_setenv ad936x_ext_refclk '<25000000>'
fw_setenv ad936x_ext_refclk_override '<25000000>'
fw_setenv ad936x_ext_refclk '<40000000>'
fw_setenv ad936x_ext_refclk_override '<40000000>'
fw_setenv ad936x_ext_refclk '<50000000>'
fw_setenv ad936x_ext_refclk_override '<50000000>'
// ... reboot to take affect
rebootI equipped my rev.C. pluto with a similar, more simple circuit.
OS commands for switching between external and internal clock work only if the rev. resistor is modified accordingly.
Petronel,
from 10MHz OCXO (squarewave) you can extract 50MHZ harmonic with crystal and buffer this with inverters and feed into pluto.
Divided by 2 can be used for LNB!
Found this somewhere, do not remember where.
25MHz for the pluto is out of spec as far as I remember , might work or not.
In a second step you may sync the OCXO to GPS ... ... always good to have enough ham projects
I do not recommend to remove original TCXO because you have to apply a lot of heat. Disable it by EN input and place the new TCXXO elsewhere on a small PCB.
No need for removal, disabling is sufficient, check schematic.
Try before modification, because modification is not easy. You need soldering equipment and skills 
.
Best inject from external for the rev. C!
As far as I remember the SW recognises the HW revision and rev D commands shall not work on rev C HW.
Basically the command switches a GPIO which controlls the switchi g HW. I modified my Pluto and had to add a parallel resistor to the rev resistor. The same generates an analogue value which is evaluated at startup. Check the associated schematics.
Someone using a CDCE913?
It is claiming low jitter, but no data with repsect to phase noise.
Whats about generating 100MHz with a ADF4351, which is claiming low phase noise VCO?
Divide this by 2 (50MHz) and 4 (25MHz) for Pluto and LNB. ADF4351 can be refrenced by 10MHz OCXO or GPSDO.
Lucien,
This looks interesting.
On your web you state that bare PCB can be supplied.
Can you give us more information about the price, shipping and how to order?
Tnx, Frank
I uninstalled the DigiUSB driver, unplug and plug again.
Now the Relay is recognized as a HID USB-Input device and it works as expected .... 
Hm, this is the only one HID relay. Due to the fact that all other control apps fail to control the relay it may not have an ID at all?!
I will try to remove all other external USB devices .....
Ok.
I see the ID in SDRconsole, there seems to be no valid Serial-ID. The same issue I faced with other control apps for this kind of USB-relays 
I have this one. Recognized by win10 but not by sdr-console. I tried some other app, but no success. These do not recognize it.
If someone can read the attiny of a functional board, the content may be flashed into mine. Relays driven by pin 2 and 3.
Can someone point to a working usb HID relay?
I bought one (HW-343) which does not seem to work on Win10.
I can confirm that it works .... ip:xxx.xxx.xxx.xxx
Insights......fine alignment from outside via screw.
40dB coupler
Pluto shall be able to run on 10MHz with appropriate modification of config file.
Is there a reason why you put the multiplier?
BTW: The level matters; there is an impact to the signal quality. Check TCXO mod thread.
May be you can apply the USB/GND modification described here
at about 7:40
BTW: The removal of the TCXO is outdated, it does not need to be removed, it can be disabled.
