** Update ** In the interests of sharing my findings, I have now got it working. What I have done: - Reworked L12 - this improved things greatly ( I must have had a fault there). - Reflowed joints on

My experience is on QCX+ rather than QDX but for what its worth : Having put a very very light smear of heatsink compound (standard white silicone/zinc stuff) on the flat faces that get screwed to

Mike Ah yes! I too remember now. Hans did say somewhere that the different audio ICs in the v3 took more current. If Dave's measurement is accurate his is taking a little more than normal. But not a

On Mon, Aug 1, 2022 at 03:52 PM, John Rabson wrote: I seem to recall a question in my IEE (1966?) fiinals which asked me to outline the design of a 1kW transistor AF amplifier. I asked a neighbour who

I think the 100ma RX current value was from early QDX history and with the various upgrades most recent builds have been averaging out in the 140-150 ma range. I believe there was a note to this

We hear about all the problems on here, so I thought I'd post something positive. I recently installed updated 1.08 firmware chips for my original QCX 40 & 20m and QCX mini 30 & 60m. The minis have

I seem to recall a question in my IEE (1966?) fiinals which asked me to outline the design of a 1kW transistor AF amplifier. I asked a neighbour who worked in semiconductor research if the examiners

Dave, This test shows if T2 is wound and installed correctly. How much down is LSB? If it is around possibly 50dBthen the secondaries must be wound and connected correctly. Fundamentally there is no

Yep: https://www.mouser.com/new/nxp-semiconductors/nxp-mrf1k50h-transistor/ As used in the Elecraft KPA-1500 (two of them, which gives a great deal of overhead). And I do have CK-722's. They came in

Jason, The next step would be to verify IC1. It should have 5volts on the input and 3.3volts on the output. A correct input and no output would mean a bad IC1. I am using the fact that the current

I did do the sweeps with a dummy load on all bands and the USB graphs look fine albeit that the LSB graphs don't look as low as possibly they should do, so maybe the unwanted sideband rejection isn't

If the 5V and 3.3V regulators are hot, it would follow some other components will also be hotter than they should, especially I/C’s. Finding same should point you in the right direction.

Yes, I see 5V on the output of IC2. Jason KB1ZOK

Hi Hans, wow that was quick! Thanks for confirming, I see the site is now updated. Hopefully will have a working unit this weekend :D 73 Elia M0ZHN

Hi Elia 3 and 3a are the same manual. I have just amended the website to make that clear. Thanks for pointing this out to me. 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl

Good morning, I just received my QDX and was lookin on the QRP-Labs website to find the correct manual for the PCB that I have, the PCB I have is Rev 3a but the website only has the manuals for Rev 3.

Hi Mark, Did you solve your problem? I just received a ready built 20m mini on Friday, but it’s not receiving, I checked on the same antenna on the big rig where there are strong signals. I have the

Dave, One comment to Alan's post: Audio and RF Sweeps need to have a 50ohm dummy load connected to the antenna to work correctly. As Alan does suggest, using the terminal Audio and RF Sweeps help in

You mean the Audio Filter sweep? I've never seen it say no signal but there are obviously problems around your LPFs. I have done quite a bit of probing with my You must rectify the obvious first. You