Re: Sound of CW during practice vs. live using QCX+

Gary Bernard

Jim, wall warts can be very noisy. I have had good results using a wall wart from Meanwell. You might look in to their 15 V product. I get 6 watts on my 20 and 40 QCX plus.
Regards, Gary W0CKI

-----Original Message-----
From: Jim McCusker (K3YO) <jmccusker@...>
Sent: Fri, Jun 18, 2021 11:59 am
Subject: Re: [QRPLabs] Sound of CW during practice vs. live using QCX+

Thanks to everyone who commented on this issue.  First, I did transmit into a dummy load and got the same result.  But I just figured out what's going on.  I recently ordered a rechargeable LiFePO battery which provides 9V and 12V output that just arrived today.  I disconnected my 12V wall charger from the QCX+ and hooked up the battery, and low and behold, normal sidetone when I started transmitting!!  Not sure exactly what was happening, but the battery clearly made a huge difference.  Perhaps Hans may have some ideas about what's going on, but at this point I think I'll just stick to using the external battery.

Thanks to everyone for the quick responses, hopefully my experience may help others.

Jim / K3YO

On Fri, Jun 18, 2021 at 10:53 AM Ronald Taylor <wa7gil@...> wrote:
Jim, it certainly isn't normal but can happen with some antenna configurations. If you are using one of the popular end fed or OCFD designs, a resonant center fed dipole without a balun or even just being too close to any radiating portion of the antenna, you are probably getting RF issues. If the sidetone sounds normal with a dummy load and bad with an antenna, then RF getting back into the audio circuits via the headphone jack is one of the likely culprits. Some have added a capacitor from the audio output to ground. .01 - .1 uF soldered to the bottom of the board across the headphone jack works. I've used that mod to correct this problem on a few QCX Minis. 

Lots of discussions on this group regarding antenna improvements are there for the reading as well.

Good luck .. Ron

On Fri, Jun 18, 2021 at 6:14 AM N3MNT <bob@...> wrote:
May be RF getting into circuitry.  Try transmitting into a dummy load.

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