Peculiarites when using Pluto GPO0 for keying

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Peculiarites when using Pluto GPO0 for keying

Post by OZ7TA » Wed Dec 13, 2023 3:01 pm


I have just finalised Langstone V2 transceiver with a Pluto, consisting of a "Control Unit" housing the Raspi, Pluto and support circuits and band specific "Frontends" housing PA, RX/TX relay, LNA and RX filter.

Pluto is version C/D with external OCXO. SW is F5OEO version 0303 (like my Pluto version B used for DATV on QO-100). Th C/D specific patch from F5UII is implemented. I use the Pluto GPO0 for keying the TX and I have implemented the "GPO0 disable" circuit using GPO1 to prevent keying durin Pluto calibration.

In the ongoing "Set to Work" process I have noticed two peculiarities:

1. During start-up, in the very last seconds of the "Loading" screen, GPO0 goes high and consequently keys the TX, but there is NO RF. When the "Loading" screen disappears after a couple of seconds, GPO0 goes low and the Langstone is ready for operation.

2. If one during receive presses "SET", chooses "TX att" and adjust the TX level using the scroll wheel, GPO0 goes high and keys the TX. As above there is NO RF output an the Pluto is still in receive mode, howver with antenna disconnected ude to the TX/RX relay is in TX position. GPO0 stays on until one presses "PTT". Then RF comes on and ona can press "PTT" once more and everything is back to normal.

Nono of the peculiarites are critical, but nevertheless I wonder if others have experienced same or similar phenomenons.

vy 73

Jorgen, OZ7TA

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Re: Peculiarites when using Pluto GPO0 for keying

Post by Pa3fbx » Thu Dec 14, 2023 10:51 am

Hi Jörgen, i am also working with Langstone on a Pluto but as adviced I am still using an very old f5oeo version of pluto. Portsdown where Langstone is incorporated does not like the older versions and ptt is switched directly out of the raspberry gpio.

So I never bothered with the f5uii ptt board.
I have that working on other Pluto,s so I know what you mean.

I may test it if this is the same here but than again I wonder why you would do it that way.

Main advantage of Langstone and portsdown is a hard wired ptt. Both going in and going out.
I will use the pluto ptt for remote control the ptt when not using Langstone nor portsdown if I set the raspberry to port forwarding and control the pluto via sdrconsole or dat easy but than you do not have this problem...

Best regards.

I am currently controlling from 1 MHz upto 10ghz..

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Joined: Thu Apr 26, 2018 9:36 am

Re: Peculiarites when using Pluto GPO0 for keying

Post by g4eml » Thu Dec 14, 2023 12:20 pm

I have just checked on my test system and I cannot reproduce the problem with adjusting Tx Att. My TX relay always stays off.
I can't think of anything that could cause that behaviour at the moment.

Regarding PTT during startup, the Pluto sets all of its GPO pins high when it boots, so if you have a relay connected to just one pin it will turn on during the start-up. The GP1 modification was designed to stop that happening by only keying the relay if GP0 is high and GP1 is low. You say that you have this modification but it sounds like it might not be working correctly.

Langstone supports using GP1 for this if you have set 'Copy Band Bits to Pluto' to Off. GP1 will then always remain low.
If 'Copy band bits to Pluto' is On then you will need to ensure that the least significant band bit is always set to zero for this to work correctly.

Colin G4EML

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