Hi All, I am looking for someone hopefully local or at least in the UK to repair my 80m QCX. I will pay for the repair. My QCX was delivered fully assembled ?and worked perfectly for a time but will not now transmit. I suspect that I may have transmitted when the antenna was not connected although things appeared to go ?astray ?when I changed from 12 to 15 volts psu?
Roger Taylor
G4CGU
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Shout out to Mustafa Tan for the lightAPRS and tip
My two lightAPRS units are presently being tested on the ground for a
possible pico balloon launch in June. Thanks to the excellent
instructions and engineering by the lightAPRS team, I had an easy time
setting up these APRS trackers. An important tip, make sure you place
the libraries in the correct file.
Thanks Mustafa for a great product.
Regards, Fred NT6T
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Re: Load impedance for Si5351a?
I also wonder about how well the Si5351a would react to an AC short.
Steve, I ran a U3S with a TX muting that simply shorted the output of the coupling capacitor to ground via a BS170. It is still working. But the consensus was that it is not a good idea. I've no real knowledge but I do not see the loading being critical for use as a calibration tool. Maybe the 5pF is to maintain a sharp waveform. It is fed into BS170s in QRP Labs projects, much more than 5pF. 73 Alan G4ZFQ I'm thinking about putting in a series resistor between the
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QCX beacon enhancement possibility
#poll
I was thinking about a possibility for a feature that could be incorporated in these radios Hans has been designing.? Since the ability to interface with a GPS is already there it would be an interesting option to have a menu item that could turn on a feature which appends the latituge / longitude GPS coordinates to the beacon.? I wanted to poll the members of this list to see how many others think this would be a valuable feature and if there is enough interest perhaps Hans could add it to a future firmware release if there are enough remaining resources on the microcontroller.? I was thinking that this could allow the beacon to act as an emergency locator transmitter when configured as such.? There could be other reasons for it as well. So the question for this poll is:? Please choose your level of interest for addind lat/long to the beacon function. Best regards Joe ve3vxo
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Re: QCX-SSB: SSB with your QCX transceiver
For those who are interested; there is now an improved version of the QCX-SSB experiment, it can be found here:?? In the meantime, I got quite a number of experimenters who reported a successful modification of their QCX and could make QRP SSB contacts.
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Note that if you plan to upgrade, it is important to remove C31 and add a 10uF capacitor at C32. This will resolve an issue with Q6 (which was not digitally switching resulting in degraded IMD and thermal instability). This fix together with the more accurate signal processing of the new firmware, improves the IMD performance, carrier+side-band rejection and spectral purity considerably. Please let me know how this works out for you. Note there is still room for further optimizations like mitigating the PA/key-shaping introduced phase-errors (that occur especially at smaller amplitudes), and the effect that reducing C32? improves the IMD.
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Another interesting thing to try out is the use of constant-amplitude SSB feature (set drive parameter to 8); this modulation scheme will solely transmit speech-information via the phase of the carrier (PM). This of course degrades the IMD performance, but quite unexpectedly this seems to be quite beneficial in weak-signal conditions when your signal just needs to be popping out above the noise-floor to make yourself heard: it occurs to me that using a constant-amplitude with worse IMD will actually improve the intelligibility in these cases.
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73, Guido
PE1NNZ
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Well, it appears that the QCX-17 is getting out on 15m too...
The QCX-17's lpf does attenuate output on 21060 kHz a few dB...could bypass it, I reckon.
72 / 73,
Bill, N4QA
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Load impedance for Si5351a?
I am building a general purpose LF/MF/HF/VHF/UHF "crystal calibrator" using a Progrock and a QLG1.? But I am not sure how to deal with the RF outputs from the Progrock.? I do have them AC-coupled through 0.1 microfarad capacitors.?
The Si5351a data sheet only specifies it for a 5 pF load.? I've read in other places that 50 ohm loads result in poor crosstalk between the outputs.? But this is of little concern in the current application.? I am a bit concerned about heating....the Progrock is drawing >50mA with some combinations of output frequencies and the current does seem to depend quite a bit on the load impedance (even a few inches of open-circuited coax has a noticeable effect).? I also wonder about how well the Si5351a would react to an AC short.
I'm thinking about putting in a series resistor between the Progrock/blocking capacitor and the output of my box, or an L network of resistors, to reduce the loading on the Si5351a while providing a low impedance source (50 ohms perhaps), since there seems to be more output power than I need for this specific purpose.? At some point I may add a multiplier circuit to produce microwave harmonics - that would benefit from lots of drive, so I don't want to attenuate too much and have to amplify back up again.
Any useful thoughts on this topic?
73,
Steve VE3SMA
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Thanks Bill for your reply, yes you were correct I should have fully scrutinised the manual. As my old boss used to say "if in doubt go back and read the instructions". Unforetunatley the rig no longer transmits so I am now trying to find some one locally to help me.
73 Roger G4CGU
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Re: QSX to be shown at FDIM this year?
If you haven't been to one of these conferences, put it on your Bucket List. With possibly one exception, all of the speakers are top-notch, and the list of speakers includes Hans. His talk last year was both entertaining and informative, and I'm sure it will be the same again this year. The only thing that could make it better is a QSX order form! There are plenty of other events that make it fun, too (e.g., Vendor night, show-n-tell, banquet), plus the Dayton Hamvention is about a half-hour away. FDIM is a "two-birds-with-one-stone" item on your Bucket List.
Jack, W8TEE
On Tuesday, April 9, 2019, 8:19:17 AM EDT, SkipF, NT1G <skip.flem@...> wrote:
On Tue, Apr 9, 2019, 6:07 AM John AE5X < ae5x@...> wrote: FDIM would be even better... ;-)
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John AE5X
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I've been doing that successfully for years. No need for even the heat-shrink. Works wonderfully. Here's
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Re: QSX to be shown at Friedrichshafen this year?
One can hope!!
Jack, W8TEE
On Tuesday, April 9, 2019, 6:07:51 AM EDT, John AE5X <ae5x@...> wrote:
FDIM would be even better... ;-)
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John AE5X
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Re: QSX to be shown at Friedrichshafen this year?
FDIM would be even better... ;-)
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John AE5X
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QSX to be shown at Friedrichshafen this year?
Anyone know if QSX might be ready by Friedrichshafen this June 21-23?
<URL:>
eagerly watching every day,
72/73 de Ken N9VV
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?°À³å(¥Ä)³å/?
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Another idea to try:? Invert your thinking.? The switch doesn't have to be the stationary part.? I attached one to the end of a short stick and put some heat shrink tubing around to guide the wire down the stick and make everything nice and neat.? Hold the thing in your hand and tap it on any convenient surface, even your knee!?? However this is for specific circumstances like you are on a tight budget, you are counting grams for a portable SOTA type gig etc.? For portable ops with higher speeds I really like my Porta Paddle made by American Morse Equipment especially for a rig with built in keyer.? It is still pretty light and when strapped to your thigh allows you to operate almost like at home.
On Mon, Apr 8, 2019 at 2:15 PM R. Tyson via Groups.Io <tysons2= [email protected]> wrote: I wanted a small lightweight key for portable use. Ended up using micro switches. These are fixed to a strip of plastic cut from one of those white chopping boards sold cheaply in supermarkets.
The key can be held in one hand and operated with one finger of the other hand. You can sit back comfortably and don't need a flat surface to put a conventional key on. I have had some very nice keys over the years but these are by far the easiest and most comfortable to use. It is easy to send good? morse with these cheap substitutes. Extending the lever part of the micro switch makes it a bit slower to send morse with. What's the normal procedure when conditions are not good ?? Slow down and send good, well spaced and easily read CW, that gives the other guy a sporting chance of copying you. I had a 14 minute CW rag chew recently and, despite poor conditions, the other guy copied everything I sent with my micro switch key. Why not use the one on the QCX board ?
Mine are in diecast aluminium cases so I needed off board keys.?
Here's a couple of photos, make your own variations
?Reg? ? ? G4NFR
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Hi Dennis,
I have seen them before, there are some ex-army keys that look quite similar.
I have had some good straight keys in the past including the Junker key - see photo below.
The little micro switch keys are so simple, so cheap and soooo easy to use. It is much easier to send good CW while sitting comfortably and not needing anything to put it on. One finger does all the work, or you could use a thumb for a change....
Reg? ? G4NFR
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Hi
Your little key is probably lighter than mine. If it works for you then great..
I found this a number of years ago, It was used by Indian rail way workers out on the line doing repairs.
They would climb a pole and hook up a pair of wires so they could telegraph the office. I did not get the sounder that would have been used with the key
Dennis
AG4TD
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I wanted a small lightweight key for portable use. Ended up using micro switches. These are fixed to a strip of plastic cut from one of those white chopping boards sold cheaply in supermarkets.
The key can be held in one hand and operated with one finger of the other hand. You can sit back comfortably and don't need a flat surface to put a conventional key on. I have had some very nice keys over the years but these are by far the easiest and most comfortable to use. It is easy to send good? morse with these cheap substitutes. Extending the lever part of the micro switch makes it a bit slower to send morse with. What's the normal procedure when conditions are not good ?? Slow down and send good, well spaced and easily read CW, that gives the other guy a sporting chance of copying you. I had a 14 minute CW rag chew recently and, despite poor conditions, the other guy copied everything I sent with my micro switch key. Why not use the one on the QCX board ?
Mine are in diecast aluminium cases so I needed off board keys.?
Here's a couple of photos, make your own variations
?Reg? ? ? G4NFR
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Jim, glad to here that You dropped a zero! Otherwise I would have to look for an alternative capacitor. But having a Q of 300 is OK for me, even if I loose some power in it.
73 Axel DF1ET
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Sorry Axel I guess I dropped a zero when I typed 30.? Still a capacitor in the hundreds range is terrible and a good capacitor should be 10 times that or more. The capacitor I use in my magloop has a Q factor of 5000 for example.? Many people use the poor plastic dielectric variables designed for tuning AM transistor radios of the '70s in antenna tuners and are happy making tons of QSO's.? Losing power in your tuner and transmission line does not mean you will not make contacts.? You will, and go ahead and get on the air with whatever you can manage.? As someone pointed out, even if you lost 50% of your transmitted power, your signal would be received 3db down from what it could be, and that is only half an S unit.? If you really get into QRPp and want to start working at 100mw or less, then you start to consider the crazy stuff like those precious milliwatts. Otherwise just go build something and have fun!
Joe ve3vxo
On Sun, Apr 7, 2019 at 12:47 AM, Joe Street wrote:
"polyvaricon" AM tuning capacitors (with a Q factor of about 30! according to W7ZOI's tests)
I worry about this, because using other tuning capacitors than these would be difficult ("big"). I did a search for W7ZOI's test and found this . According to page 19, he measured Q = 540 at 10 MHz and Q = 340 at 6.5 MHz. Can I relax or is a the value of 30 still right?
73 Axel DF1ET
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jjpurdum
Don, ND6T