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JT65 DIGITAL SPLATTER
Posted: Fri Jul 07, 2017 1:38 am
by mark1161
I am seeing redundant signals, (see screen shot attachment) above and below my signal, when TX on JT65. What should I be looking at to correct this situation?
Thanks
mark
WA2DIY
Re: JT65 DIGITAL SPLATTER
Posted: Fri Jul 07, 2017 4:45 am
by w9mdb
Looks like 1st one above is 120Hz and 2nd one is another 240Hz up.
So looks like 60Hz interference which presents itself as 120Hz.
Power supply, wall worts most likely culprits.
Start unplugging things...
Also make sure everything is common grounded too.
de Mike W9MDB
Re: JT65 DIGITAL SPLATTER
Posted: Fri Jul 07, 2017 2:25 pm
by w-u-2-o
Gent's: I moved this to the Digital Mode sub-forum.
I'm only seeing significant spurs above your TX frequency, at roughly +1.2KHz and +4KHz.
I see your drive is quite high, at 77W. With PureSignal off, which is the case, -30dBc IMD is not abnormal for the amplifier that is built into the 100W ANAN series radios when operating at such a power level.
It's hard to successfully run PureSignal in automatic mode with digital modes. However you can turn it on, use the two-tone function and Single Calibrate to lock in a linearization correction, then proceed to operate. As long as you don't move the VFO the linearization correction should remain valid. This may significantly reduce the IMD, if they are in fact IMD products.
Another thing you might check for is a sample rate mismatch somewhere. What are you using to move sound between WSJT-X and PowerSDR? VAC? Voicemeeter? Are all of the virtual audio cable devices set to 16 bit, 48KHz in the Windows Sound Control Panel, both on recording and playback tabs?
73!
Scott