WSPR211 r2242 and IQ transmitter

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G6AIG
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Joined: 2010/11/17 - 11:28
WSPR211 r2242 and IQ transmitter

I am using WSPR 2.11_r2247 (I think latest version)
with an SDR-radio ( TxRx Ensemble )
I am using the built-in sound card from the motherboard (Asus P5B)
which uses the Analogue Devices AD1986 chip, and "SoundMAX" software.

I shopuld mention that the setup works well with PowerSDR software,
including TX I and Q signal adjustment to 96HHz and with SDR-radio to 192KHz

When I use WSPR,
On receive, everything works fantastically well, including the
frequency calibration offsets.

Hovever, on Tx, I get VERY unbalanced amplitudes from the 2 channels,
(nearly double the signal on the 0/180 input than the 90/270).

Concequently, I have next to no sideband image-rejection

The I and Q transmit sliders help a little, but with maximum settings,
I only get around 10dB rejection.

When I start PowerSDR software up in parallel,
the wspr test signals are properly balanced, and I lose the
calibration offset.

When I switch back to just WSPR, and update the LO, the unbalance
returns.

There seems to be something screwy going on here with the IQ outputs.
Perhaps it is specific to my sound-card? Has anyone else trodden this path?
Thanks, Hugh G6AIG