Re: I think I broke my QMX...
Perhaps try checking Q508.? With QMX on in receive mode, you should see close to your supply voltage on both D and S.
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I'm not sure about what the Farnell catalog shows, but the suffixes on the BS-170 by on-semi start with a D, and all refer to lead-forming and packaging (reel vs whatever).? Ones with no suffix are what is delivered with QMX; all are electrically the same.
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Re: I think I broke my QMX...
I misread the value for L503, so I replaced it with a 47uH inductor, with no change in the receiver.
?
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Re: Newly assembled QMX, SWR=1.5 with dummy load
I concur with the previous recommendations.
SWR into a dummy load from the QMX should show 1.0x:1 on the lower bands, increasing to perhaps 1.1x on the highest band.
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Re: I think I broke my QMX...
I replaced L503 with a through hole 330uH inductor (I don't have any smd parts available).? It looks ugly, but I think there are solid connections to the PCB.? Unfortunately, the RF still isn't getting through. I didn't try to resolder to many joints - they were before I started messing with the diode.
?
?
?
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Re: QMX+ kit build - RX birdies on Digi and loud wide tone on CW
Oops, I need to read more carefully before responding.? If you put the QMX+ in CW mode with wsjt-x receiving, you will see the CW filter bandwidth at a high volume.? This is because wsjt-x normalizes the display for gain across the entire 4kHz bandwidth,? but the QMX+ filter has dramatically reduced the energy outside the filter.? Set the CW passband to 'none', and that will go away.
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Re: QMX+ kit build - RX birdies on Digi and loud wide tone on CW
The high-amplitude at 700Hz looks like you have I/Q mode enabled on the QMX+ .?
It must be disabled for digi mode use with wsjt-x?
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Re: Newly assembled QMX, SWR=1.5 with dummy load
Hi Jan,
Check the winding count of the transformer T507. Check for its proper soldering to the PCB.
?
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My QMX Plus is approximately 25% down on the Test Certificate power, so I am looking to replace one of the BS170 FETs. The Farnell catalogue has many different suffixes to their BS170 devices. Should I select a particular device?
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Lee and Hans! On Mon, 2025-04-21 at 12:57:14 +0000, Lee wrote: I cannot address the math here but can say that the Ten-Tec Pegasus,
Jupiter, Argonaut V and 6N2, all of which I owned used Weaver method
detection in the DSP section of the radios (also used Weaver on transmit)
and had excellent quality audio with no holes within the audio bandwidth of
interest. So if you can find the technical info any of these it may help ? I will see if I can find some info on these. I have made some experiment using the QMX USB output, which a feed through the proposed filter. The attached C-program runs on Linux. The filters are standard LP filters: Gaussian, Butterworth, Chebyshev (1dB ripple) and Elliptic (1dB, -60dB), of order 4, 6, and 8. The program is not fancy, but it shows the principles of the filter. It can be used for CW and SSB reception. 73 Anders SM5KAE
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Re: QMX+: Hearing a tone only when LSB is selected
Yes, I don¡¯t hear it on my QMX HB either.?
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On 4/21/25 I had a CW practice / rag chew session
on 20 meters. I worked no stations:
Conditions were OK. SSN = 108, SFI = 156, A = 14, K
= 5.
I heard several very weak stations calling but they were
too weak to work. My next CW practice session will be?April 23 at 16:00 EDT / 20:00 UTC on 20
meters.?Anyone and everyone is welcome. This
practice is intended for operators who are new to CW or
they need some practice. IT DOES NOT MATTER HOW POOR
YOUR CW IS. Mistakes are OK. Poor fists are OK. Slow
speed is OK. Really slow speed is OK. This practice is
meant for you to improve your CW. I will do my best to
adjust to your skill level. Operate at any power level.
If several stations show up, I will operate as a
round-table control station. I will do it as a
round-table so everyone gets a chance to transmit.
Please listen to my directions.
Details:
Date - April 23 2025
Time - 16:00 EDT? 20:00 UTC
Band - 20 Meters
How to find me - I will find a clear frequency and call
CQ. Go to the Reverse Beacon Network and search for my
call sign AB8DF.
That will tell you what frequency I am on. Tune
your station to that frequency and if you hear me give
me a call. If there is a QSO in progress, please wait
for a break in the action. Then send your callsign. If I
hear you, I will invite you to join the QSO and start a
round-table QSO.
Reply to this email if you have questions.
IT DOES NOT MATTER HOW POOR CW IS
Ed
AB8DF
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Re: Feature Request - CAT for SSB Input
Hans,
Thank you.
Peter LaRue
AI7YN
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On Mon, Apr 21, 2025 at 11:51 AM, Matti OH6BEX wrote:
If I manage to remove it, I'll replace it with a conventional zener.
I happen to have some 3,6V 400mA zeners, can I use these?
Matti, please read QMX QMX_plus D109. So you should use only (SMT) 3.6V 500mA.
?
Resistance Vdd - Gnd is 183 ohms so I should replace D109. But how? It sits in very tight place.
I don't have a QMX+ here in the moment. I'm not sure there is enough place to do the following. I would use a sharp pencil type tip for the solder iron, set the temperature to 350¡ãC, put a bit flux on D109, a bit solder at the tip and touch one side of D109. After a few seconds I would try slightly to lift this side of D109 using tweezers. After this the same for the other side until D109 is free.
?
73 Ludwig
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On Mon, Apr 21, 2025 at 01:52 AM, Randy Paulson wrote:
Seems reasonable considering, but the Diagnostic screen shows 12v+ = 13v, VDD = 6.6, and VCC = 5.6.
Can someone explain how those values are measured and/or calculated?
?
Randy, in your situation VDD is basis to calculate the shown voltages. It is assumed VDD is 3.3V. Because of the existing difference the shown voltages are calculated wrong.
?
To change something here is on Hans list.
?
73 Ludwig
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Re: QMX only hearing static
Kai, there is a way to check CLK2 from IC204. Use Terminal - Hardware tests - Rf filter sweep. As long as you are in this function CLK2 is on. Check voltage at IC501 and IC502 pin1 and pin4. Each should show around 1.6V (pulses with 3.3V high and 50% duty cycle.)
?
73 Ludwig
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Re: Adjustable Power Level
On Sun, Apr 20, 2025 at 07:17 AM, SM5EIE /Gunnar wrote:
Nice article, but I see two problems...?
1) It will also attenuate received signal
2) If built into connector it vill be hot
Yeah, precisely because an attenuator attenuates in both directions makes it unsuitable for this use case.
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Greetings Anders,
I cannot address the math here but can say that the Ten-Tec Pegasus, Jupiter, Argonaut V and 6N2, all of which I owned used Weaver method detection in the DSP section of the radios (also used Weaver on transmit) and had excellent quality audio with no holes within the audio bandwidth of interest. So if you can find the technical info any of these it may help ?
Interesting stuff! 73 de WA3FIY Lee
toggle quoted message
Show quoted text
------ Original Message ------ Hello Hans
On Mon, 2025-04-21 at 12:45:03 +0300, Hans Summers via groups.io wrote:
> Suppose we want to listen to a CW signal transmitted at 7020 kHz.
We
> set the VFO to 7020-12 = 7008 kHz. The mixed signals contain the
sum
> and difference of these frequencies: 14028 and 12 kHz. Only the 12
> kHz components pass through the lowpass filters in front of the
ADC,
> and appear digitally as cosine and sine of a 12 kHz signal.
>
What about a signal occurring at 6996 kHx? This is the "superhet
image", it also mixes with the 7008 VFO to produce a 12 kHz IF signal.
In your scheme I don't think you are handling this image signal? The 6996 kHz signal mixed with 7008 kHz will appear as -12 kHz (note the
sign) and 14004 kHz (removed in analog LP filter) at the ADC. Mixing it
with the 12 kHz IF results in -24 kHz, which is stopped in the digital
LP filter. There will be some remaining signal due to imperfections in
the Tayloe mixer, LP and ADC but this problem is also present in other
implementations.
The I-Q signals differ between +12 and -12 kHz. To be explicit, at the
output of the ADC, the 7020 kHz signal will appear as I = cos(om*t) and
Q = sin(om*t) (+12 kHz), while the 6996 kHz signal becomes I = cos(om*t)
and Q = -sin(om*t) (-12 kHz).
After the IF mixer: I = 1 and Q = 0 for the 7020 kHz signal, and
I = cos(2*om*t) and Q = -sin(2*om*t) (-24 kHz) for the 6996 kHz signal.
73 Anders SM5KAE
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Re: Newly assembled QMX, SWR=1.5 with dummy load
Jan, First I would check the dummy load with a digital ohm meter. Is it actually 50 ohms? Next double check whatever cable or jumper you are using to attach the QMX to the dummy load. Check for shorts and/or opens. Double check your solder connections on the RF output of your QMX for cold solder joints or bridges.
Dean - KC9REN
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Re: Trying to capture 2x16 LCD signal...
Hi Hans - This is truly exciting news that the LC CAT command can be targeted for the next firmware release.? I absolutely plan to make good use of this new feature when it becomes available.? My only follow on question is if one more CAT command could be considered to reduce power output to 1/2 or 1/4 to recreate the SWR tuning utility built into the QMX firmware now?? Thanks again for your special efforts to accommodate some edge use cases.?
It's already on my list, to provide?a way to reduce QMX output power. And in the end it the aim is that EVERYTHING that you can set on the QMX itself, or in the terminal, should be accessible also via CAT commands. The reduction in power is easy to do but, I wanted to spend some time testing if everything is OK since effectively the voltage drop goes across the Q507 power amplitude modulator transistor, which dissipates all the power. I wanted to do careful testing to make sure it doesn't mind. I believe it should be OK, after all in two-tone testing and SSB etc., this is already what happens; but I didn't quite reach the "convinced" threshold.
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Keith G3WGE