Topics

#20m #20m


Paul Ross
 

Got my QCX+ for 20 meters up and going. Couple of resistors missing in the kit, but those arrived today.
Smoke test passed.
Alignment OK - reasonably satisfied at this point -- did 3 passes through I/Q process.
Set menu for "straight" keying.
About 3.5 watts output on  13.8 volts. Need to make a more exact measurement when I get a better dummy load -- the QRP Labs kit is now somewhere between here and Turkey.
"Noisy" audio -- doesn't seem to be the volume control. RF getting into something? Comes on fine after initial boot mute, then may "crackle," sometimes quit. Restarting does the same cycle.
Decoder is decoding random noise. Need to find a signal to listen to.
Hints, or a place to start checking?
Otherwise, all seems good.
/paul W3FIS


Paul Ross
 

Also, I have the "S" meter turned on. It fluctuates appropriately with the background noise, but when the audio dies, so does the "S" meter display. Does that help?  

First thing tomorrow is to go over it all again looking for a cold/bad solder joint someplace....


Shane Justice
 

Paul,
You should only be aligning your radio while it is connected to a dummy load. 

If you had it on an antenna, you will need to repeat the alignment connected to a 50 ohm dummy load.

As far as the receiver noise goes, HF is dominated by atmospheric noise. There is some hiss one can hear in the receiver that is noise in the radio, but it should be fairly low, compared to atmospheric noise. Again, proper alignment should minimize internally generated noise.

What time of day are you using your 20m radio? 20m is usually a daytime band, so if you try it when it is dark at your location, you may hear nothing on the band but static crashes from distant lightning.

Not knowing your experience level with HF, this is as close as I can guess as to what may be happening with your radio.

I hope this helps.

Shane
KE7TR


On Oct 24, 2020 at 14:38, Paul Ross <w3fis@...> wrote:

Got my QCX+ for 20 meters up and going. Couple of resistors missing in the kit, but those arrived today.
Smoke test passed.
Alignment OK - reasonably satisfied at this point -- did 3 passes through I/Q process.
Set menu for "straight" keying.
About 3.5 watts output on  13.8 volts. Need to make a more exact measurement when I get a better dummy load -- the QRP Labs kit is now somewhere between here and Turkey.
"Noisy" audio -- doesn't seem to be the volume control. RF getting into something? Comes on fine after initial boot mute, then may "crackle," sometimes quit. Restarting does the same cycle.
Decoder is decoding random noise. Need to find a signal to listen to.
Hints, or a place to start checking?
Otherwise, all seems good.
/paul W3FIS


Paul Ross
 

I did the alignment on a dummy load. Went over EVERYTHING with a jeweler's loupe and touched up ANYTHING that looks a little marginal with a soldering iron. All seems to be fine now. It had all the symptoms of a bad connection -- thermal -- warm up problem, noise. However, the usual "bang on case" of my vacuum tube days produced no joy.

FWIIW, have had my ticket since 1957 (KN2VZY, K2VZY, K1QBC, W3FIS) and am an EE by training. Got into this game in the tube era and used to scrounge old TV parts... I have soldering iron burns to prove it....

I have a small (1 watt) dummy load, so didn't want to push it. Have a QRPLabs dummy load (20) watt kit on the way, so when that is put together, I will run through the alignment a second time. I do hear the WSPR and maybe a JT8 <gasp> station on, as well as a couple of other CW stations, so I think I am pretty well out of the woods by this point.

Thanks for your suggestions.


Paul Ross
 

As to TOD, tests mid-afternoon yesterday, and about noon today. I usually work 40 meter CW (7030, 7055). I didn't (fat chance...) need another 40 meter radio, so decided to have a go at 20 meter single band. I do have a 20 meter "Hilltopper," but it is a bit awkward to use, so the nice LCD display of this radio looked good. I like to do field QRP when the weather is good, so this looked reasonable. That "Mini" radio in the works is interesting...


Paul Ross
 

Thought I had this sucker licked. After a few minutes - 5 or so, something likely heats up. I loose audio and side tone. Rig still keys up OK. Would a can of spray electric coolant be the next step? I've been over all the joints a couple of times with a jeweler's loupe and don't find anything amiss.

Advice at this point?


Paul Ross
 

Well, I'm completely stuck now. Went back to check alignment with dummy load. Can not get above a 4, or bar to move when trying to peak BPF. Continuity on 4 winding transformer. Position of tuning capacitor has no effect.

Audio dies within a couple of seconds of turning it on.

I do not have have access to a 'scope or much test equipment.

Is there anyone in the group who might take a look at it? Will cover postage both ways and something for your time.

Thanks!


Ronald Taylor
 

I’d be happy to do that for you Ross. I’ll send you a separate email with info. 

73... Ron

On Sun, Oct 25, 2020 at 16:09 Paul Ross <W3FIS@...> wrote:
Well, I'm completely stuck now. Went back to check alignment with dummy load. Can not get above a 4, or bar to move when trying to peak BPF. Continuity on 4 winding transformer. Position of tuning capacitor has no effect.

Audio dies within a couple of seconds of turning it on.

I do not have have access to a 'scope or much test equipment.

Is there anyone in the group who might take a look at it? Will cover postage both ways and something for your time.

Thanks!










Paul Ross
 

Thanks!  Tried a general reset, and now have control of BPF, BUT, radio still dies on me after a few moments.


Ronald Taylor
 

Paul, did you just send me the following note from a different e-mail address? :

"One more thing, but it should be obvious, mine is the 20 meter version.

Have you ever hooked the GPS unit up to one of yours for time discipline?

I'm using my FT-817ND for WSPR at the moment, but the radio might be 
another possibility.

/paul"



My email app is suspecting phishing ... weird .... anyway, if this was from you, No, I've never used the GPS for time discipline on a QCX. I only use it to 
calibrate the system and reference oscillator frequencies. I don't do WSPR, only CW and you can't do CW and GPS at the same time because they use the same connections to the microcontroller. I do have a VFO that I discipline with the GPS and it has a clock function. I think the QRP-Labs station clock is the best option for using GPS for time discipline. Be careful using the QCX for WSPR. Make absolutely sure your antenna SWR is good before transmitting. Also, it's good practice to lower the operating voltage on the rig to something like 10 volts to cut the transmitter power at least in half so as to not overstress the finals with the 100% duty cycle transmission for 2 minutes at a time. Again, for WSPR operation, the QRP-Labs U3S is a much more versatile solution. 

Best 73 ... Ron


On Sun, Oct 25, 2020 at 4:36 PM Paul Ross <W3FIS@...> wrote:
Thanks!  Tried a general reset, and now have control of BPF, BUT, radio still dies on me after a few moments.