Martin - Thanks for your detailed WAE report. This was both my first time trying this contest and trying to log using N1MM. I ran my 20m QCX-mini to an 80-10m EFHW up about 30 feet here on the Atlantic coast of Florida. Only worked about 12 EU stations (mostly DKs) before N1MM stopped working. Not sure what happened yet.?
Which logging software did you use and what was the interface cable??
Congratulations on your effort! WAE is quite a challenge especially with the QTC exchange. Sigs here were too weak for me.?
¡ª¡ª¡ª¡ª¡ª¡ª¡ª¡ª-
Jim?
N7RCS
Palm Bay, FL
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Re: QDX: Anyone else having a problem with image rejection?
#qdx
On 10/08/2022 20:18, Hans Summers wrote: are you correctly referring to image rejection (the superhet image 24kHz away from the wanted signal) and if so, how are you measuring that? Or are you referring to unwanted sideband rejection as shown in the AF sweep screen Hans, I came across your comment and wondered what it meant. I was under the impression IQ balance was responsible for reducing, if not eliminating image responses. The unwanted sideband is an image. If fed with the basic "audio" IF an SDR program will show say 48KHz bandwidth, the LO in the centre with all signals duplicated each side of centre. A USB signal will appear opposite the centre as an image, a LSB signal. If the QDX is set to receive the USB signal the image is a LSB signal 24KHz below it. Feed the SDR program with IQ signals then images are cancelled. IQ balancing differentiates between negative and positive frequencies, signals below and above the LO. The unwanted sideband is an image and is cancelled along with any real signals on that frequency. I have no idea about how the software works but that is the way I see soundcard SDR working. There is almost always an offset. It is recommended to maintain a fixed offset so IQ cancellation is optimised there. IQ balancing is needed because of small variations in the hardware. I do not remember anyone suggesting image and unwanted sideband are different. Presumably any software frequency conversion would have perfect IQ balance if that came into it? 73 Alan G4ZFQ
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Re: QCX WARC Party - August 2022
I managed a couple of qso on 30m in the 1900 session.? On holiday without my qcx so using kx3. Antenna was a 20m vertical with an extra bit of wire to bring it close to 30m resonance.
73 Peter gm0eul?
On Tue, Aug 16, 2022, 8:21 AM ON7DQ Luc < on7dq@...> wrote: My 1300Z report .... well, nothing to report !
Bands were in very bad shape, I called CQ for 30 minutes on 30m, NIL.
Also got very few spots on RBN.
Tried 17m for 15 minutes , again NIL ...
My 1900Z report ... more luck : 2 QSO's on 30m: I1GZG and SP7HLV, then 2 on 60m: F4WDZ and F1JKN, but alas no QCX's worked.
F4WDZ on 60m was Pete G4IOA, operating from France.
Rigs used : my QCX Classic's for 20m and 40m, both used on the "one lower" band, in a correctly tuned random endfed.
Key : my new 'Gelatelli' straight key, built for the SKCC WES last weekend, see picture here and you will understand , hi.
73,
Luc ON7DQ
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I do the same with my FT-818 instead of QDX. It works great. PI 4 headless controlled by the smartphone through VNC over wifi is a wonderful solution.
Moreover, if the PI is connected to the internet through e.g. home wifi, you can operate it from your smartphone whenever in the world (provided you have 4G) and do QSOs even away from the shack! I love it, that is my preferred way of operating FT8 (when I am at the shack I prefer CW or SSB, indeed).
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Re: QCX WARC Party - August 2022
My 1300Z report .... well, nothing to report !
Bands were in very bad shape, I called CQ for 30 minutes on 30m, NIL.
Also got very few spots on RBN.
Tried 17m for 15 minutes , again NIL ...
My 1900Z report ... more luck : 2 QSO's on 30m: I1GZG and SP7HLV, then 2 on 60m: F4WDZ and F1JKN, but alas no QCX's worked.
F4WDZ on 60m was Pete G4IOA, operating from France.
Rigs used : my QCX Classic's for 20m and 40m, both used on the "one lower" band, in a correctly tuned random endfed.
Key : my new 'Gelatelli' straight key, built for the SKCC WES last weekend, see picture here and you will understand , hi.
73,
Luc ON7DQ
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I tried my luck in that, hoping for some nice DX. After some painful QRP hours I remembered I had a transistor PA which i used to use in the 1980s with my FT7 and pulled it out. WAE does not have a QRP section so I was underpowered anyhow.
From there on, at least I got it going a bit even if in the end 215 QSOs for 36 hours is not much. With a bit of luck I got through even to ZL. Sometimes the pileups were impressive.? Strange to me was, that even with RBN reports from US around 15 to 24 DB the Run mode did not work for me at all but US? stations came back mostly on S&P. Antennas used a EFHW 41 m long 12 m up and a GP for 20 m . Trees around me are mostly higer.
No QTC traffic for me, I am just too slow in CW and also on the keyboard. Impressive at what speed QTCs are received.
Now I hope the DX stations report their log to Lotw so that I can increase my DXCC account.
Martin
DK3UW
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Re: QCX WARC Party - August 2022
sorry I totally forgot and saw the reminder too late.
Martin
DK3UW
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Hi Milt
I shamefully admit, that I mostly suck it and saw.?
On Mon, Aug 15, 2022 at 9:22 PM Milt < w8nue@...> wrote: Hans, In your design of the BPF (L12), did you assume, or measure, stray circuit capacitance?? My calculations, using a nominal AL of 4.9nH per turn squared, suggest that the capacitance values need to be 10-15pF more than the manual values.? This appears consistent with an input capacitance of 13pF on the A terminal of the FST3253. ?
Am I missing something? ? Hello Milt
I think there are some problems if the sweep goes beyond the specified band limits. However I have corrected this in a beta version that I am working on.? On Tue, Aug 9, 2022 at 6:39 PM Milt < w8nue@...> wrote: Hans, Are the frequency limits ignored during the filter sweeps?? That is, can the start frequency be less than frequency min, or the maximum of the frequency sweep be greater than frequency max as set in the band configuration? On Aug 6, 2022, at 11:00 AM, W8NUE <w8nue@...> wrote:
?Hans, Thanks for keeping us posted on updates/changes.
I do have a question regarding the band configuration: since it shows a selectable Start Frequency and Step Frequency I conclude that I need to know the Default Number of Steps to be able to control the Sweep Width.? Is this correct?? Is that number about 50?
Have I missed something? On Aug 6, 2022, at 9:46 AM, Mont Pierce KM6WT <de.km6wt@...> wrote:
?On Sat, Aug 6, 2022 at 05:56 AM, Hans Summers wrote:
The vertical marker showing the band center went missing in version 1_04.
I noticed that for 20m the Band Sweep setting was different than 80/60/40 so I just changed 20m sweep step from 100000 to 50000 (like 40m), and the center frequency appeared. Nice to know you're on top of it though.? I'll update to 1_05 when it's released. Each firmware release always seems to have some goodies?? hi hi Thanks, Mont
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Got my QDX kit on July 25 and got to find the artwork error on my own before the new build instructions were posted. It seems to be working OK except there is a weirdness. IC-9 likes to live around 2.5V - as it should. IC-7 likes to live around 0.81V (both amps). Following the voltage drops leads me to believe that the PCM1804 is sourcing current out its analog input pins and the opamp is correcting for that. The positive input is also low - but I'm attributing that to the low differential input impedance - I've removed the 100 ohm resistor to separate the amps and it persisted on both of them. Before I start lifting pins on the ADC I thought I'd ping for any ideas. I'm also considering leaving it alone since it does work, it's just not right.
?
Totally different - I built mine for 12V and power it from 9V. Power out is about 1.85W on 40M and the transistors and regs stay cool as a cucumber.
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Hi Colin,
You are correct.? To get the drive needed to overcome the capacitance in the gates of the BS170, you need the two gates of the 74ACT08 in parallel.? ?If one of the two gates has failed, it will load down the other gate most of the time, and you will not get the squarewave output required by the BS170s.? This will show up as a lower voltage when measuring using a DMM on DC.
The DMM DC voltage test is not the most accurate, as some failure modes will not show up.? The best test is with a dual trace oscilloscope with one probe on one set of the parallel gates and the other probe on the other gates.? You should see two 5volt square waves 180degrees out of phase.
I am trying to keep it simple.
73
Evan
AC9TU
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?
A quick post on my hotel op in Virginia. ?I used my $70 Surface 3 and my $95 Wonder-Wand. ?Brief QSO with a station in Ohio.?
Richard
N6IJK
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¡°?If any fail this test, you will need to replace IC5, the 74ACT08 transmitter driver.¡±
It is notable that this chip has 4 and gates and they are used in parallel. Two gates in parallel are linked to two BS170s in parallel. (I am sure you?know that Evan, but I thought it was relevant for people following along.)?
--
Colin Kaminski - K6JTH
https://www.qsl.net/k6jth/
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Marc,
The best test that I know of is to use one of the Transistor Testers sold on Amazon or eBay:
Others are OK, though not as good for inductor or capacitor tests:
73
Evan
AC9TU
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Marc,
You do not describe the test circuit that you say verifies the BS170s.? You should have very high resistance between the gate and the source, as well as the gate and the drain.? Also a high resistance from the source to the drain without a connection to the gate and the positive lead of the DMM on the drain.? Can you describe the test circuit you are using?? What is the value of the voltage being used for the test?? How are you turning on and off the gate voltage to verify that the MOSFET does act as a switch and not just a resistor?? Here is a DIY test circuit for a MOSFET:
Note that the BS170 is an N-channel MOSFET.
If you use something like the above and the LED turns off and on with the switch on the gate, then your BS170s are good.?
You have stated that the receiver current is the same as before removing the BS170s.? The next step is to verify that IC2 can still provide 5volts and that it is not very hot to the touch.
Can you tell us if the LED comes on flashing, then goes solid after a few seconds?? If so, and if IC2 is not overly hot and the output of IC2 is 5volts, then I suspect your current measurement may be off.? I would test the RF and Audio Sweeps in the terminal program and then see if FT8 signals can be decoded with WSTJ-X software.? You will need to connect an antenna for the FT8 test.
If all that checks out, you are ready to test the transmitter.? I start with using the Transmitter Test function in the terminal program.? You should have the QDX back on the dummy load for these tests, even though the BS170s are still not in the QDX.? Verify that you are getting 2.5volts DC on the gate pads with the BS170s not installed.? This is done while pressing the PC t to key the transmitter.? The LED should flash the 3 pulses and pause pattern, showing that it is going into transmit.? When you release the t on the PC, the gates should all read 0volts.? You need to test all 4 BS170 gate pads.? If any fail this test, you will need to replace IC5, the 74ACT08 transmitter driver.
I think that is enough for now.? Let us know what you find and we can go from there.
73
Evan
AC9TU
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Re: QDX gettin' out on 20 !
Wait a minute!
I do have a pbs, an LED and a resistor.
So, it's WSJT-X 'Tune' followed by my pressing the n.c. pbs.
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Re: QDX gettin' out on 20 !
Hi Gary.
All I have to do is punch the 'Tune' button in WSJT-X and the AH-4 does the rest :0)
72,
Bill, N4QA
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Re: QDX gettin' out on 20 !
Bill
How do you tune the AH-4 with the QDX?
Gary
W9TD
?
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Marc. To measure current you need to have your DVM in series with yor power supply. I.e break the supply feed at the power supply. Connect your positive probe to the positive connector of the p/s and the negative probe to the positive wire going to the radio.
Roger
Get
Without the BS170¡¯s my receive current is the same. ?I am measuring the current from center pin of power connector with + probe and touching the - probe to the ground of coax. ??
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Without the BS170¡¯s my receive current is the same. ?I am measuring the current from center pin of power connector with + probe and touching the - probe to the ground of coax. ??
--
Marc
N8LO
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Re: QDX burned on start-up
I would put getting the RF out of your power supply high on the priority list.? First rule of troubleshooting is to fix what you know is wrong.
I would not be comfortable with my power supply voltage (or DMM) swinging around like that.??
I have a nice old Simpson analog meter which seems to be immune to RF; it is good for a check.
73, Don N2VGU
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Peter GM0EUL
Leonardo IW5CWC
ON7DQ Luc
Colin Kaminski
Gary W9TD
Donald S Brant Jr