Langstone Discussion Forum

[G8GKQ]

Hi Ian

The USB Mic Dongle is optimised for electret. There is a bias voltage. I use a standard Yeasu fist Mic with a Plessey SL6270 preamp/ALC IC to feed the USB dongle. Still available on eBay.

And I would welcome the provision of a "ppm" software compensation adjustment for the TCXO. I have a high stability oscillator in my Pluto, but it has at least 5 kHz error at 23 cms.

Dave, G8GKQ

[g4eml]

I am not sure how it can be done on the Raspberry Pi but the frequency accuracy of the Pluto can be trimmed by editing xo_correction in the config.txt file.

When you connect your Pluto to a PC using USB it will appear as a usb drive.
You will find the config.txt file in that drive.

xo_correction has to be set to the actual frequency of the oscillator. This is nominally 40 MHz or xo_correction = 40000000

If you have a 6 KHz error at 23cm that would be about a 185 Hz error at 40MHz so a value of
xo_correction= 39999815 would probably get you close.

Once you have edited the config.txt file you have to eject the drive using the windows toolbar whilst leaving the Pluto connected. That forces the value to be saved permanently.

Details of how to do this are on the analogue devices wiki for the Pluto.

I am sure there must be a way to do this on the Pi. If I can work out how to do it I will add it to the Langstone code. My Pluto is fitted with an adjustable tcxo which can be precisely set, so I have never needed to do it.


Colin.

[g0mjw]

It’s already included a Mike!

If you set the transverter Tx offset and Rx offset to different values the SAT flag appears along with an extra ‘MONI’ button. Selecting Monitor allows full duplex.

It has reminded me that the offsets are not actually displayed correctly, I think a positive offset actually shifts the frequency down. I will fix that in the next release.

Colin.

Ah - didn't spot that. Must RTFM.

Mike

[G8XZD-TV]

Hi Ian

The USB Mic Dongle is optimised for electret. There is a bias voltage. I use a standard Yeasu fist Mic with a Plessey SL6270 preamp/ALC IC to feed the USB dongle. Still available on eBay.

And I would welcome the provision of a "ppm" software compensation adjustment for the TCXO. I have a high stability oscillator in my Pluto, but it has at least 5 kHz error at 23 cms.

Dave, G8GKQ

Thanks Dave, will investigate tomorrow,
PS thanks for your hardwork too with this and Portsdown A27 - both work a treat.

[G8XZD-TV]

I am not sure how it can be done on the Raspberry Pi but the frequency accuracy of the Pluto can be trimmed by editing xo_correction in the config.txt file.

When you connect your Pluto to a PC using USB it will appear as a usb drive.
You will find the config.txt file in that drive.

xo_correction has to be set to the actual frequency of the oscillator. This is nominally 40 MHz or xo_correction = 40000000

If you have a 6 KHz error at 23cm that would be about a 185 Hz error at 40MHz so a value of
xo_correction= 39999815 would probably get you close.

Once you have edited the config.txt file you have to eject the drive using the windows toolbar whilst leaving the Pluto connected. That forces the value to be saved permanently.

Details of how to do this are on the analogue devices wiki for the Pluto.

I am sure there must be a way to do this on the Pi. If I can work out how to do it I will add it to the Langstone code. My Pluto is fitted with an adjustable tcxo which can be precisely set, so I have never needed to do it.


Colin.

Thanks Colin - hadn't thought about looking there.
73, Ian.

[DL5BCA]

Hi @ all,

I'm playing around with the TRX a little bit.
I have a 70cm repeater on my doorstep in 500m ...
Now I wanted to program the corresponding offset Frequenz of -7.6MhZ in FM ...
I wonder thati have to enter 7.6 - and not -7.6MHZ - to be able to set a negative Txvtr TX frequency offset.

Is that ok?

I would also like to have the Pluto in a case near the antenna ...

73 Thomas DL5BCA

BTW: the software is great ...

[g4eml]

I have never tried it on a repeater. That was not what it was originally designed for.

Yes the offset is inverted. You may need to set + offset instead of -.

I will correct that in a future release.

Colin.

[DL5BCA]

Hi Collin,

Are there any News??

73 Thomas DL5BCA

[g4eml]

Hi Thomas,

Thanks for reminding me, I have made the changes but forgot to upload them.

The Langstone code has now been updated to correct the sign of the Tx and Rx offsets.

Settings mode now shows the offset and also the real Rx or Tx frequency.

Offsets in existing configuration files should be adjusted automatically.

Colin G4EML

[DL5BCA]

ello Collin,

many thanks for your effort.

I did the update.

It struck me that to set a 7.6 mhz offset frequency I have to turn my mouse for an hour ...

Since you can set the offset frequency for each band separately, I would like it to be displayed above the actual frequency display when set. Maybe a "switch" for switching the offset frequency on and off is also good.

I know you didn't program it for FM modulation, but there are some FM relays at 23cm and it would be a shame if you couldn't work with such a great option.

Thanks for all the effort. Here are some OMs working to get the Longstone up in the air.

73 Thomas DL5BCA