Jim Bennett / K7TXA

I love my multiple QCX rigs, but.... after having an Elecraft K3/P3 for 10+ years and now a K4D, I feel "blind" when using my QCX+ rigs - no pan adapter / display. Kind of like back in the olden days when we had separate transmitters and receivers: one had to go tuning around on the RX for an open spot or a CQ, then bring the TX to that frequency. It's a bit better with the QCX+, as the TX is already there, but one must still traverse the band manually until an opening or a CQ'er is found. Fun, but after a while, frustrating.

So, I've ordered am RSPdx SDR. Planning on putting it on an antenna switch so I can visually "see" the entire band, zoom in on a signal and determine if it is a CQ or not. If none are found, then an open spot can be determined for my own CQ.

At first I was thinking about using one of the Internet SDR sites, but realized that what they hear and what I hear may not be the same. I imagine their antennas are a tad better than my flagpole vertical!

Wondering if other folks are doing the same with your QCX? 

Jim / K7TXA
Eagle, ID

SKCC 10447
BUG 301

Joshua KJ7LVZ

I hear you but, no.  If I'm using my QCX it is for simplicity's sake.  I have some high-dollar shiny equipment I can use for that job if I want to be quick, efficient, or want to look at stuff, but if when I'm using my QCX, I just want to spin the encoder and ride the key.  Maybe, just maybe, I'll think about putting something together for portable use with an RTL-SDR, Pi, and 7" screen at some point but not now.  

If you want an idea, I'd use the Easy TR switch from Pacific Antenna to switch out your SDR on transmit.  You'll lose 3db on RX due to splitting the signal but it worked for me when I originally added an RSPdx on receive to my FT-991A.  http://www.qrpkits.com/ezseries.html#eztrsw  If you don't want the drop in signal, there's the hupRF tap buffer board.  I use it in my Kenwood TS-590S as a panadapter output.  If you can figure out how to wire it in to the QCX so it doesn't get signal on TX, it is the best option.  I got a bit berated on another board for using one as "it's not necessary" but I sure like it.

There are other options such as MFJ but what's the fun in not soldering something yourself?  Haha.  

Good luck.


Daniel Walter

 I also have a K3/P3 combo and I love it. My 4 QCXs don't compete with that. Where the QCXs shine is on SOTA and POTA outings. Especially SOTA. Even comparing them to the IC-705, they still come out looking good. The KX3/KX2 have them beat, but only if you don't consider the price. 
73, Dan  NM3A

John Kirby


As you know I'm sure...
A 200 Hz CW filter is TQQ tight fQr lQQking rQund the band
200 Hz is outstanding when the pileup is on you :>))

Suggestion ...
... either mod and or bypass the QCX audio filter
... then use an external es/or variable audio filter

First hand experience from 991 es 7300

72 73
FM19 on DELMARVA Peninsula

Roelof Bakker


I agree with your sentiment regarding the use of a waterfall / spectrum display.
Since 2008 I have been tinkering with SDR's for reception at LF and once experienced the
benefits of a visual representation of band activity, it is hard to live without it.

I have just added a rf-out and USB-port to my Elecraft K2.
Lex, PH2LB helped me out with the USB port:


The rf-out port is a JFET source follower, loosely coupled at the input of the mixer of the

I am using a SDRPlay RSP1A running under SDRConsole, providing a waterfall and spectrum
display putting the in-built displays of high end radio's to shame.

SDRConsole is via com0com connected to either my logbook or contest program.
Both RSP1A and the logbook or contest program can control the K2 and visa versa.

Maybe this is a bit over the top for a 'simple' CW transceiver like the QCX, but it can be

I have a QSX plus for 80 and 40m and I am tempted to add a rf-out port.
This way outboard T/R switching can be omitted and hence the chance to destroy the RSP1A is

A waterfall display sure helps. Wednesday evening I have been testing the rf-out port of my K2
from 160 to 10M. Ending up on 10M, the band was dead (it was 1 hour 40 minutes after sunset).
Just one CW signal could be spotted on the waterfall display. This appeared to be V26IE from
Antigua and against all odds, I was able to work him with 5W from my K2 and a wire antenna.

Last night the story was repeated as just another single CW station showed up on 10M. This
time I worked Barbados, 8P0P at around the same time, 19:50 UTC.

Roelof, pa0rdt

Ron Carr


I added a Teensy 3.6 and Audio Board to one of my QCX+'s.   It was an interesting project but is perhaps a bit of overkill.  The QCX+ has I and Q tap points, you could buffer these signals and feed them to a sound card and have a waterfall on a computer without too much effort.