Date   

Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

Ronald Taylor
 

Vance, you are correct, the BPF adjustment is independent of the volume control setting. The IQ Bal and Hi and Lo Phase null adjustments are the ones that are dependent on the setting of the volume control. If you are peaked at the high end of 7 on the BPF and are not at max or min setting on C1, then you are good to go at that level. 

73 .. Ron

On Wed, Aug 18, 2021 at 12:00 PM Gary Bernard via groups.io <garybernard2=aol.com@groups.io> wrote:
Sounds to me like you did a great job. 20 has been dead lately. Try late afternoon and early evening. 
GL, Gary W0CKI 


On Aug 18, 2021, at 12:06 PM, wb8yyy via groups.io <wb8yyy=yahoo.com@groups.io> wrote:

Vance

nice work, just built a 20m mini here. 

the 7 level on BPF peaking means little - it changes as you adjust volume control.  as long as you get a pronounced peak, all is well. 

the other nulling calibration is more important, and sounds like that went well.  note it takes several iterations and each menu setting and knob to get it optimized. 

20m propagation has not been great recently.  i managed a few WAE contacts this past weekend, but not much since.  so hang in there. 

5 volts on coax center pin has me spooked - check it again with no antenna attached.  I confess I have not looked into that, check the schematic and see who else comments.  there should be a blocking cap that isolates the center pin from the circuitry - and with EFHW likely introducing a DC short - I am saying how can this be if the blocking cap is shorted - check it again. 

73 Curt wb8yyy
fellow QCX traveller


Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

Gary Bernard
 

Sounds to me like you did a great job. 20 has been dead lately. Try late afternoon and early evening. 
GL, Gary W0CKI 


On Aug 18, 2021, at 12:06 PM, wb8yyy via groups.io <wb8yyy@...> wrote:

Vance

nice work, just built a 20m mini here. 

the 7 level on BPF peaking means little - it changes as you adjust volume control.  as long as you get a pronounced peak, all is well. 

the other nulling calibration is more important, and sounds like that went well.  note it takes several iterations and each menu setting and knob to get it optimized. 

20m propagation has not been great recently.  i managed a few WAE contacts this past weekend, but not much since.  so hang in there. 

5 volts on coax center pin has me spooked - check it again with no antenna attached.  I confess I have not looked into that, check the schematic and see who else comments.  there should be a blocking cap that isolates the center pin from the circuitry - and with EFHW likely introducing a DC short - I am saying how can this be if the blocking cap is shorted - check it again. 

73 Curt wb8yyy
fellow QCX traveller


Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

Arv Evans <arvid.evans@...>
 

Curt and Vance

Re. +5VDC on the coax connector,

If your DVM has fairly wide bandwidth it is possible that it is reading the
average of the RF above ground.  This happens when the RF is floating
above ground level (usually when a capacitor is used for DC isolation).

Some rectifier circuits for dummy loads also measure the average RF
voltage in a way that adds this to the actual DC and give an impression
of more power than is really there. 

Arv
_._


On Wed, Aug 18, 2021 at 12:06 PM wb8yyy via groups.io <wb8yyy=yahoo.com@groups.io> wrote:
Vance

nice work, just built a 20m mini here. 

the 7 level on BPF peaking means little - it changes as you adjust volume control.  as long as you get a pronounced peak, all is well. 

the other nulling calibration is more important, and sounds like that went well.  note it takes several iterations and each menu setting and knob to get it optimized. 

20m propagation has not been great recently.  i managed a few WAE contacts this past weekend, but not much since.  so hang in there. 

5 volts on coax center pin has me spooked - check it again with no antenna attached.  I confess I have not looked into that, check the schematic and see who else comments.  there should be a blocking cap that isolates the center pin from the circuitry - and with EFHW likely introducing a DC short - I am saying how can this be if the blocking cap is shorted - check it again. 

73 Curt wb8yyy
fellow QCX traveller


Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

Vance.Langer@...
 

Curtis: I was under the impression that the peak level on the bpf isn't affected by the volume. I guess I could check it again and make sure. I was able to get a peak that is between fully open and fully meshed.

Ron: I think I measured 5v on the dummy load while  doing my output test, but ill double check that.


Re: QRP Labs August 2021 newsletter

VE7VXO
 

I assumed he meant the spoon you use for spoon feeding all those who keep pestering about the QSX. ;)


Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

John Pagett G4YTJ
 

Gents,

Don’t worry about the 5V on the coax centre pin. It comes from the output of IC3C (pin 8) - at least on the QCX+. It’s possible that Hans has used different pins on the mini, I haven’t checked, but the principle remains the same.

This output produces the alignment signal for setting up, but is attenuated by a 120k resistor (R 43). When the alignment signal is off the gate output sits at 5V but the 120k resistor will mean that you can connect a dummy load or antenna without issue.

Regards,
John
G4YTJ


Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

Curt wb8yyy
 

Vance

nice work, just built a 20m mini here. 

the 7 level on BPF peaking means little - it changes as you adjust volume control.  as long as you get a pronounced peak, all is well. 

the other nulling calibration is more important, and sounds like that went well.  note it takes several iterations and each menu setting and knob to get it optimized. 

20m propagation has not been great recently.  i managed a few WAE contacts this past weekend, but not much since.  so hang in there. 

5 volts on coax center pin has me spooked - check it again with no antenna attached.  I confess I have not looked into that, check the schematic and see who else comments.  there should be a blocking cap that isolates the center pin from the circuitry - and with EFHW likely introducing a DC short - I am saying how can this be if the blocking cap is shorted - check it again. 

73 Curt wb8yyy
fellow QCX traveller


Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

Ronald Taylor
 

Vance, that high 7 range reading is probably fine, as long as you are not at fully open or full meshed on the C1 trimmer. 

I checked my QCX just now with DC reading DVM on the BNC connector and find 5 volts on the center pin as well. But when terminated with 50 ohm dummy load it goes to zero. My guess is we are seeing the local oscillator signal from the mixer but that's just a guess. Anyone else have any ideas?? 

73 .. Ron

On Wed, Aug 18, 2021 at 10:49 AM Vance.Langer via groups.io <Vance.Langer=protonmail.com@groups.io> wrote:
Hi everyone,
I finished up my QCX Mini (what a fantastic kit!) and noticed a few things while doing the alignment. Firstly, I was only able to set the BPF Peak to high 7, almost 8. Is this too low? Is there anything I can tweak within the hardware to improve this? The rest of the alignment went well.

Secondly, when trying to determine the power output with a DMM and the 50 ohm dummy load I noticed I could get just over 5 watts output with 13.5V in, reading off the charts in the manual. However there's a lingering 5v on the center coax pin. What's the deal there?

I got it hooked up to my EFHW for some listening, there didn't seem to be much happening on the 20m band but my antenna placement was less than ideal, I'll try again later. I did manage to listen in on a couple of QSOs and the built-in decoder seems to do well! Does anyone have recommended decoder settings that work best?

Thanks a lot everyone for the help and advice, this is an awesome group!


#qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

Vance.Langer@...
 

Hi everyone,
I finished up my QCX Mini (what a fantastic kit!) and noticed a few things while doing the alignment. Firstly, I was only able to set the BPF Peak to high 7, almost 8. Is this too low? Is there anything I can tweak within the hardware to improve this? The rest of the alignment went well.

Secondly, when trying to determine the power output with a DMM and the 50 ohm dummy load I noticed I could get just over 5 watts output with 13.5V in, reading off the charts in the manual. However there's a lingering 5v on the center coax pin. What's the deal there?

I got it hooked up to my EFHW for some listening, there didn't seem to be much happening on the 20m band but my antenna placement was less than ideal, I'll try again later. I did manage to listen in on a couple of QSOs and the built-in decoder seems to do well! Does anyone have recommended decoder settings that work best?

Thanks a lot everyone for the help and advice, this is an awesome group!


Re: Battery & Charger Recommendation For SOTA

va3rr
 

Ikea recently had a clearance on their AA 2450 mAh NIMH batteries in W & VE. Made in the Panasonic factory in Japan, AFAIK. A great choice for all the reasons Richard outlined...

If I were a SOTA "mountain goat", I would be looking standard-size Li-on cells in a plastic battery case, because every kilo counts...


Re: Integrating a tuner in the QCX+

VE7VXO
 

These days it seems everybody wants the convenience of a tuner built into the radio but I would rather the tuner is at the far end of the line. That approach has some great advantages.  In the picture I posted the tuner is at the antenna base so you aren't running high SWR on the transmission line which compounds loss.  If you are running  matched line you can afford a smaller and lighter (and cheaper!) line for a given amount of accepted line loss.  In that case it was a 5/8 wave with elevated radials I set up above my tent and is an excellent DX antenna.  A short length of RG-174 to the sleeping bag fits through the zipper without letting mosquitos in.  I can reach up and tune it from the tent but once tuned it doesn't need adjustment especially on 30m. I was doing that kind of stuff from high ground 25 yrs ago before the whole SOTA officialdom got going. The LED SWR bridge is in a little box with in-line BNC connectors that makes it versatile to use with many rigs (picture).  The Elecraft T1 is usefull in the same way but is expensive and not weatherproof and requires an extra shielded cable to initiate remote tuning which isn't a big deal unless you are trying to go super lightweight.  The K3NG open source design I mentioned a few posts back is basically the same thing and you can build it into a waterproof box  Since it's open source you can do a lot with it including powering and triggering it through a bias tee on the single RF coax cable.  I guess I'm trying to convince the original poster (and others) not to build a tuner into your rig.  It is just my opinion, but I do urge you to look at how much of your precious QRP power can dissapear in the line if you do it that way.  It can easily be a full S unit!

Joe


Re: Battery & Charger Recommendation For SOTA

Richard Tomlinson G4TGJ
 

NiMH AA cells. Widely available, cheap, safe, you probably have some already, interchangeable with other devices etc. For QRP they are perfect.
--
73
Richard
G4TGJ


Re: QRP Labs August 2021 newsletter - no reply from Hans

Timothy Fidler
 

OK , here is  wet afternoon with Hans LEFT THE BUILDING   (as per Elvis )

 

idea Nbr one. basically all analogue transmitter design - AM.

It is a 6W PEP AM transmitter design for forty but  can equally be made for 80.  Now the xtal osc can become 
either  of 

a 7.20 or 7.16 pulled ceramic oscillator  OR it can be driven by some Direct synthesis device like Hans' VFO. 

Where this can potentially shine is converting an old  BFO type commercial radio into a one or two band transceiver OR 
it  could be a stand alone transmitter which is paired with any suitable  transmitter.  

Points to note - the audio mute mosfet was not needed.

2.  The audio low level amp was a 5322.  Any other operational amp with the same pinout  can be uses here .   

3. the high level audio amp should be able to produce  3- 4 W out and in this case an 8 W bipolar unit intended for older car radios was used.

4. The transformer is a TU024 from Mouser  ,no subs possible.  You have to use two in parallel for safety . One transformer alone can lead to burned windings. 

5. the intended microphone was a 600 ohm dynamic insert plus transformer type showing a nominal Z of 600 ohms. DO NOT use ceramic microphones here.
 
6. IN the current incarnation , the cct cannot be used on  20 mtrs because of the limitations of the driver chip ,  TC 1412N. I'll post a better driver design.

7. the Q11 transistor is a 2n 4401 type.

8.  To build such a transmitter and  not allow  CW transmission is foolish.  I'll provide a scalable schematic for that. 

TEF


 

 


Re: Integrating a tuner in the QCX+

Albert Tatlock's Greatest Hits - Vol 1
 

I did something similar like VE3VXO for a simple antenna / tuner a while ago.

Mine is a bit more bulky and made from some plastic plumbing supplies.

It contains -

A simple L match.
An LED indicator to peak the tuning.

On the top where the tuning cap is (polyvaricon) there are also two small holes.
This was for inserting a loop or simple best bent piece of solid wire handle to hang it onto tree branches etc.
I've since lost the handle so I can't show it.

The one knob tuner would usually allow me to tune at least two, sometimes three bands on one coil.

Best used with a good choke on the feedline etc.

I should have integrated one into the enclosure at the time I suppose and reduced space taken up in
the travel back.


Be


Re: U3S Clock runs slower than GPS #u3s

Alan G4ZFQ
 

Rob,

The manual lists the 4 sentences required.
When I used a uBlox 5 with my U3 I found, as you found, it did not pass the checksum test. No data was shown. That ublox only had the one extra sentence, GLL. Therefore the U3 does not simply ignore the GLL.
If yours had so many more sentences enabled then it's surprising the U3 showed anything sensible.

73 Alan G4ZFQ


Re: Integrating a tuner in the QCX+

VE7VXO
 


On Tue, Aug 17, 2021 at 03:11 PM, N1EDC wrote:
What about a simple L-match with a fixed inductance and a fixed capacitance in parallel with a small trimmer cap?  Just enough range to fine-tune your SWR for individual differences in antenna height/ground conductivity/etc?  A simple SWR bridge as others have recommended could be built in as well to give you a tuning indicator, and the whole thing could be quite small.
You and I think a lot alike.  If you build something specifically for the job at hand it can be very small, light and efficient. Below, the matching network inductor is wound around the polyethylene film canister and inside protected from moisture is an air variable capacitor.  Obviously this is OT and not about something to build into a QCX+ but illustrates the point that building for the specific need rather than something generic which you may never need is sometimes a great way to go.


 


Re: QCX+ only static on receive

 

Good to hear that Bob! From all you were saying it sounded like there was nothing wrong with the radio.
--
Julian, N4JO.


Re: Integrating a tuner in the QCX+

VE7VXO
 

W7ZOI does mention in the article that the high loss scenario would apply when the matching network is adjusted so that the capacitor sees high RF voltages, which makes sense since it is dielectric loss within the plastic sheets in the capacitor which are at fault.  If the transformation is to a low impedance this might not be the case but often people don't know the impedance they are trying to match and random wires or an off resonance doublet fed through a random length of feedline can present a wild range of impedances.


On Mon, Aug 16, 2021 at 08:22 AM, @CurtisM wrote:
I would not necessarily write off all polyvaricon tunable capacitors without numeric measurement. The zm2, blt, and perhaps the gqrp sudden tuner use these parts. They tend to be more substantial than others. The recent inexpensive qrp tuner kitted in the far east was confirmed by someone to use much lossier capacitors. Now if you wish to carry a Johnson matchbox on your next hike, go for it. It's a matter of degree, even my elecraft tuner exhibits some loss. 

Curt


Re: QCX+ only static on receive

Bob W7DIT
 

I made some improvements to my antenna last night and was able to copy one side of a QSO. Seems that the QCX+ is fine. Thanks to everyone who helped me sort through my issue!

Bob


Re: U3S Clock runs slower than GPS #u3s

Rob Giuliano
 

Left it run last night (still into a dummy load) with the GPS only putting out the 4 GPS messages: $GPRMC     $GPGSA     $GPGGA     $GPGSV
Display is showing Lat, Lon, and Alt.
Time is (if anything) half a second ahead the network time.  Since it is direct off the GPS, expected.

Suspicion: 
Since eliminating the extra GPS strings seems to be the fix, maybe the U3S doesn't ignore but tried to decode them.
This takes extra time and causes delays , and errors.

--
Rob KB8RCO