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I have a question about using the Softrock Ensemble RXTX with one of those cheap far east linear amp kits. I believe the amp is working correctly and I have set the bias voltage adjustment on the gates of the power MOSFETs (~1.0 vdc) and activated PTT (ground), I now adjust the output of the RXTX using a 2000 Hz test audio to the Line-In usine M0KGK IQ Test and use CFGSR to control PTT on the RXTX.

When adjusting the amplitude of the test IQ 2000 Hz signal to ~ -10dB with PTT active on the RXTX the power amp kicks in (output at the dummy load) and then, less then one second, the RXTX shuts off the RF output and the USB connection to the computer laptop drops.

What is the most likely cause of the RXTX RF shut off? Is it DC ground loop, RF back feeding the Softrock or sloppy connections between components? I would appreciate any input form any of you who have successfully used the RXTX with a RF power amplifier, especially the cheap kits form E-Bay and Alliexpress.

On 09/12/2020 16:05, Robert George wrote:

the RXTX shuts off the RF output and the USB connection to the computer laptop drops

Sounds like RF getting into the USB cable. Try one of those shielded cables with ferrite chokes built in at both ends.

HTH

Nick

Sounds like RF getting into the USB cable.? Try one of those shielded cables with ferrite chokes built in at both ends.

Yes, there is nothing in the Softrock that is likely to do that.
USB drop-out seems to confirm.

73 Alan G4ZFQ

Hello Alan,

Wednesday, December 9, 2020

Could the issue be power supply overload if they share the same supply? I would have thought TX'ng into a dummy load on a short coax would be unlikely to get into the USB cable? Just an idea.


Best regards,
Chris 2E0ILY mailto:chris@...

Sounds like RF getting into the USB cable. Try one of those shielded
cables with ferrite chokes built in at both ends.

AG> Yes, there is nothing in the Softrock that is likely to do that.
AG> USB drop-out seems to confirm.

AG> 73 Alan G4ZFQ


AG>