INVERTED SPECTRUM TX

[IK2NBU]

Hi Guys

i'm using sdr Lime Mini USB as IF RTX at 72 MHz, with up conversions home made HF Transceiver

To have correct USB/LSB monitor vision on RX , i must use the function "Inverted Spectrum" starting SDR console.

But on TX, I haven't found how to reverse the modes ?

so I'm forced to use USB to transmit in LSB, and vice versa.

Any suggestions ? Please e 73

Arnaldo ik2nbu

[jdow]

That hides in the definition, which can be awkward. But, that's the way it is. Click on "Select Radio". On the lower right of this popup dialog click on "Definitions". Then on the lower left of the definition you can "Invert Spectrum". You may be able to create a duplicate definition to make it a little easier. I've never tried to do this intentionally. However, I have seen it happen unintentionally.

Hopefully somebody else will appear with a better answer.

{^_^}

[IK2NBU]

Thanks, I'll try this setup

[IK2NBU]

Sorry

Transverter conversion on software SDR is not correct function in this case.

Because i need only to invert I e Q signal to swap USB/LSB operating mode at frequency 72 MHz,
that is my fix IF channel, after a mixer and a DDS VFO operating from 72 to 102 MHz.

Any suggestion ? Thanks

[jdow]

OK, let me get this straight - you need to invert for only one of TX or RX but not both?

Ah, I think I see what you did. Look at the transmit panel. You have USB selected. Try setting it to the "Sync RX" position.

TXP.png (14.47 KiB) Viewed 2309 times

I bet this helps.

{^_^}

[Max]

Because i need only to invert I e Q signal to swap USB/LSB operating mode at frequency 72 MHz,
that is my fix IF channel, after a mixer and a DDS VFO operating from 72 to 102 MHz.

I'm not sure I fully understand what you are doing? It seems from your description you are trying to use SDRC to control the Lime but you are tuning the radio by some other means because you mention your homebrew HF transverter has a DDS VFO? I'm really not sure how this would interface with SDRC?

Maybe best to draw a block diagram of your setup and post it here as an attachment so we fully understand what you have there? I am not at all sure that you should be inverting the spectrum at all from what you describe. This seems to be confirmed by the fact the sidebands are switched. All very odd.

Block diagram please. Also, is the HF transverter a kit/assembled or is it your own design? If kit/commercial can you please let us know the model number?

73, Max

[jdow]

If my guess is not right, I'd love to see a diagram of his transverter. And it would be good to know his final output frequencies? I don't like being forced to guess and drag information out with tongs and pliers.
{o.o}

[IK2NBU]

Thanks for your reply

You can see the video on my you tube channel, attached the block schematics of my RTX 50 HF/VHF/UHF, made with LIME USB and SDR Consolle.
Lime SDR work as IF RTX on fix 72Mhz, with external mixer and DDS VFO from 72 to 512 Mhz.

[IK2NBU]

Short Video presentation ( with AI translate )

[jdow]

This isn't a suitable place for a critique of the design; but, I note it may be a nightmare over some of its frequency range with regards to spurious responses.

If I read it correctly the output of the mixer is at 72 MHz. And that would be with the DDS at 122 MHz for a 50.0 MHz input. So Fif = Fdds - Fin. Your SDR software will show USB when you are receiving LSB and vice versa. The transmit path starts at the 72 MHz IF. Your monitor port will show exactly what the SDR software thinks. It's DDS should be at 122 MHz so that Fout = Fdds - Fif. So again it inverts the sideband, you transmit LSB when SDR says USB. It's symmetrical. BUT, your monitor port is monitoring the Lime's output. So if SDR says USB it will be USB.

That is the only way I can see that you'd be seeing the wrong sideband when testing. I tell myself to, "unwind, think it through, and check your assumptions." Sometimes I even listen to myself. This is the kind of thinking error I've made (at least) once before and hopefully never again.

{^_^}