Portsdown and Langstone external GPSDO

[HB9IAM]

I want to use a GPDSO reference for Portsdown and Langstone.
With a Puto rev. C and firmware V0.32 or 0.35, the synchronization is perfect.
But to transmit an image, you need the "Dirty" firmware.
After installation, the external reference doesn't work;
the Langstone still use the Pluto's TCXO.
The Putty command "fw_printenv refclk_source" indicates "refclk_source=external,"
but the reference comes from the Pluto's internal TCXO !

What's wrong ?
Pierre HB9IAM

[g0mjw]

What are you doing wrong?

Perhaps you need to specify the clock?

https://wiki.amsat-dl.org/doku.php?id=e ... export_pdf

fw_setenv refclk_source external
fw_setenv ad936x_ext_refclk_override "<40000000>"
pluto_reboot reset

Or perhaps you are using firmware for a Rev B. As you don't specify which "dirty" firmware version nor where you got it, there is no way to tell.

Mike

[g4eml]

External reference clock support was added to the official pluto firmware at V0.32 to support the Rev C hardware.
Any modified firmware based on an earlier official version will not use the external clock settings. The environment variables can still be set but they won't do anything.

Langstone is not sensitive to firmware version and should work OK with any official or modified versions.

Portsdown needs to use the modified firmware that supports DATV.

Colin G4EML

[G1BVI]

Hi All my LB GPSDO came today to use with the Portsdown/Langstone £198 ouch

I tried the Dirty official firmware and failed.. to get the external reference working.
I tried Toms 0303 and that would not transmit with the Portsdown ..
I tried other firmware all with the same result.. Most just would not tx with portsdown.
Finally though having put back the official firmware for PD4 the pluto does not TX at all.
Giving up for now, and will try and reformat and then reflash, otherwise one Pluto C/D for sale !!!
I am sure someone can get it going...


So hot and flustered....
So bottom line I gather is that with a pluto C/D and firmware v 0.31-4 g9ceb-dirty my expensive GPSDO will not function with it.

73 all

heats getting to me hi hi
nick

[G1BVI]

I give up.

The thing is only driving into another portsdown with a lime mini but its not showing any output on the band scope now?
ive re formatted and put om v 0.31-4-g9ceb and no change

On the pluto config page under M3 it reports the range is extended..
it reports both CPUs enabled and its the right version for PD4

so al seems normal !

I have a lime and as it seems I cannot add an external ref to this, in the morning will find a box and put it up for sale here £150 incl.

im sure I can find a use for the Leo Bodnar GPSDO!!


73

Nick

[HB9IAM]

Hello Nick

Now i am not alone to get the problem !

I use a trik to get Portsdown an Langstone both look to a extermal reference ! :
On the past I have modify my first Pluto by removing the poor original TCXO and
connect direct the reference, desctiveng in manny publication

Now the look is perfect !

I still hope somone find a solution for the D version !

73 Pierre HB9IAM

[Basil]

This page from Analog Devices help forums may hold an answer to checking if a Revision C / D Pluto has successfully been programmed to use an external reference:


https://ez.analog.com/adieducation/univ ... ock/432026

[g4eml]

I don't have a pluto rev D but looking at the schematic it should be possible to force the external reference to be used even if the older firmware doesn't support switching. This would need a small hardware modification.

The reference clock is selected by GPIO6 . High is external clock, low is internal clock.

GPIO6 feeds via R102 to the two switching MOSFETs which select the clock source.

So if you removed R102 and then fed 1.8V from the nearby C121 into the gate of Q2 the switch would be forced into the external reference state.

Colin G4EML

[Pheonix2024]

Hi All

Okay, I have been struggling with the external clock issue on a rev C pluto for about a week now. Based on my findings and Colin's comments, here is my conclusion. Please tell me if I am wrong.

PLuto rev C out of the box works fine with external clock. I am using a 10 MHz clock with no problems and tested with sdrangel at 1GHz and an Icom8600 rx, perfect. Happily I found this out after a week by going back to first principles and installing the original firmware rather than shelling out £150 for a 'proper' oscillator

After installing the frequency expansion all still working well.

After installing F5OEO 'dirty' firmware in order to make it work with Portsdown, the external clock input no longer works. Google AI Gemini tells me that the internal clock should be shown on the clk output but a look at the schematic shows this to be nonsense.

The fw_printenv instructions show the correct information for external clock but the external clock will not work with the F5OEO firmware.

I gather that the Langstone will work with the original Pluto firmware, so for langstone only, you can use the original pluto firmware and all will be well, I 've not tried this yet.

For the Portsdown, it appears that you need to use the F5OEO firmware but then switching back to Langstone you would need to reload the original Pluto Firmware if you want to be anywhere near your intended txrx frequency otherwise is uses the internal clock which is miles away from true it drifts like mad so no good for qo-100

73s Greg G4CST

[g4eml]

The fw_setenv instructions are just creating and setting environmental variables. You can create and set anything you like. However the firmware needs to be aware of those variables to make use of them.

The F5OEO firmware was written for a rev B pluto which did not have provision for the external clock. The variables to change to external clock were not added to the firmware until after the Rev C pluto was released.

The only option with older firmwares is to do a hardware mod to switch to using an external clock.

Colin G4EML