Portsdown 2020 power ouput low

[G3GJA]

I’m getting some problems with my Lime Mini / Porstdown 2020. Normally the output is 0dBm with the gain set at 90 on 23cms.

More often than not, on start-up I cannot get the output above -35dBm. Attempts to push is higher by winding the gain up causes the shoulders to appear when they are normally 50dB down on the peak. Carrier mode produces the same results.

I've found that if I switch to a 13cm frequency and then press Tx the power comes up and switching back to 23cms restores power on that band to normal.

I think there is some band switching in the Lime Mini somewhere around 2GHz. Is it possible that's not being set up properly on boot?

Clive G3GJA

[G8GKQ]

Hi Clive

The internal band switching is set when the Lime is called to transmit each time, not on boot, so that seems unlikely.

What LimeSDR Mini Firmware do you have loaded: DVB, 1.29. 1.30 or 1.31?

Dave

[g4hiz]

Hi Clive,

May I suggest to check the Lime calibrate configuration under M3/Lime/Config? I know that at one time, there was an issue if this was set to 'Calibrate if needed' at start-up. The level came up low as you found, but seem to correct itself after a few changes (band?). The way around this was to set to 'Calibrate every Tx' at start-up. I'm not sure if this was sorted, but I believe it was on Dave's 'to-do' list at one time.

73
Jen

[G3GJA]

You were spot on Jen! Setting the calibrate to run on every Tx start fixed the issue.

In answer to Dave's query, I'm running v1.30 and the DVB extension.

Thanks for the help.

73

Clive