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Re: QMX Hi Band V2 Receive Sensitivity

 

Hi Mike. Compared to my High Band QMX, yours seems to be at least 30 dB in the deaf direction. In your case I don't think it has anything to do with the lowpass filters because your output power measurements are very good. I rather suspect your issue is in the bandpass filter circuit. Thoroughly re-check L401, C401-C404 and all associated connections. Also check T401. Lots of potential enamel removal possibilities here. If nothing wrong there, use the schematic and verify continuity from the gate of Q508 to the "RXIN" lead of L401. Verify proper operation of Q508. This FET turns the receive RF path off during transmit. It could be off all the time. Good luck .... Ron


On Sun, Mar 3, 2024 at 2:16?PM N0MPM <n0mpm52@...> wrote:
I have seen quite a few a few posts on sensitivity on the High Band QMX, but I am not too sure what to do if it isn't up to snuff...My Low Band QMX sensitivity is about -107 to -109 dbm at the antenna bnc connector.? My new High Band QMX is running only about -75 to -77 dbm.? Not deaf by all means, but I am guessing it should be better.? Is this something that can be improved by fiddling around with the LPF windings?? Transmitter power is about 3.8 to 4.2 watts depending on band with the 9v transformer winding....

I appreciate any insights..

thanks and 73,
mike? n0mpm

Re: QMX No Power Out

 

Hey John, thanks for the reply:

All bands no power out.
Verified that no input exists to the antenna tuner.
12 Volts for power.

97 milliamps on receive.
60 meters - 141 Milliamps xmit
40 meters - 154 Milliamps xmit
30 Meters - 177 Milliamps xmit
20 Meters - 207 Milliamps xmit
80 Meter - XMIT Disabled -?

I did a jeweler's loop inspection and checked continuity for the Transformers.? Was wondering what the voltage readings should be at the pads for T501 and T507.? Also, do you know the expected Bias on Transmit for QW503-Q506?? Will check C526 specifically.??

Burt
K4SRQ
Re: Faulty Progrock2 - no response to ticket #progrock2

 

Peter,

How were you powering the ProgRock2?? What sort of voltage source, voltage level, and connection method?

73 - Steve, KW4H
Re: QMX Using Z-Match ATU Blown Finals -- Twice

 

The second failure was with Vcc at 9V. Power at about 1.2W.? Last sentence of the first paragraph.

--

Chuck, W5USJ
EM22cv, Rains Co., Texas

Re: QMX No Power Out

 

Burt,

Some questions. Your answers may help your helper.?

Are all bands exhibiting no power out?

Have you verified 'no power' using an external instrument?

What voltage level powers your QMX?
How much current is drawn in TX? In RX?

Have you checked all the solder joints at T501 and T507? Inadequate removal of enamel insulation is a prime culprit. Using an ohmmeter , check for continuity through the winding, measuring from pad to pad, not on the copper wires.

Have you inspected C526? If it is cracked you may still be able to receive but transmit will be nil.

Post a screenshot of the diagnostic page while in TX. Let's verify that PIN diode currents and PA operating voltage are correct.

JZ KJ4A?

On Sun, Mar 3, 2024, 8:13?PM Burt Wizeman <burt@...> wrote:
I have no power out, yet the oscillator is working as I hear it on my DX10 when the DX10 is not connected to an ant.? I ran hardware diagnostics on the rf filters.? They were pretty much a strange cousin of the examples in the instructions.? Not smooth at all.? Side tone sounds great!? In the diagnostics, a lower SWR was shown but no power out.? Any suggestions or further info needed?? The receiver sounds great, and the menu operation is very intuitive.? Excellent work.? Just looking for some ideas on what I can check, test points in the RF and PA sections.
Burt
K4SRQ.

Re: My QMX AGC settings #qmx #agc

 

Thanks for your agc settings. I will give them a try. 73’s

Mike Krieger


On Sun, Mar 3, 2024 at 6:02?PM Steven Dick, K1RF <sbdick@...> wrote:

Hi Folks.? I just want to pass along my AGC settings.? They are somewhat based on what others have posted plus some of my own tweaks. I have not spent much time on the noise filter parameter as the many times I played with it, there was not much in the way of noisy conditions.??

The receive audio on CW now sounds very pleasing to me from relatively weak signals to relatively strong signals as well as operation in a busy band. .? Outstanding Hans!??

?

-Steve K1RF
QMX and Ham Radio Deluxe

 

I have discovered by accident that the HRD profile for "Kenwood TS-570" seems to work better with the QMX than most of the other Kenwood profiles. The audio does not disappear, CW reports to the logbook as CW, and the A > B VFO, A/B VFO, CW, CW-R, FSK and FSK/R buttons all work as expected.? Woo Hoo!?

73,? Ron K9ID
QMX No Power Out

 

I have no power out, yet the oscillator is working as I hear it on my DX10 when the DX10 is not connected to an ant.? I ran hardware diagnostics on the rf filters.? They were pretty much a strange cousin of the examples in the instructions.? Not smooth at all.? Side tone sounds great!? In the diagnostics, a lower SWR was shown but no power out.? Any suggestions or further info needed?? The receiver sounds great, and the menu operation is very intuitive.? Excellent work.? Just looking for some ideas on what I can check, test points in the RF and PA sections.
Burt
K4SRQ.
My QMX AGC settings #qmx #agc

 

Hi Folks.? I just want to pass along my AGC settings.? They are somewhat based on what others have posted plus some of my own tweaks. I have not spent much time on the noise filter parameter as the many times I played with it, there was not much in the way of noisy conditions.??

The receive audio on CW now sounds very pleasing to me from relatively weak signals to relatively strong signals as well as operation in a busy band. .? Outstanding Hans!??

?

-Steve K1RF
QMX Hi Band V2 Receive Sensitivity

 

I have seen quite a few a few posts on sensitivity on the High Band QMX, but I am not too sure what to do if it isn't up to snuff...My Low Band QMX sensitivity is about -107 to -109 dbm at the antenna bnc connector.? My new High Band QMX is running only about -75 to -77 dbm.? Not deaf by all means, but I am guessing it should be better.? Is this something that can be improved by fiddling around with the LPF windings?? Transmitter power is about 3.8 to 4.2 watts depending on band with the 9v transformer winding....

I appreciate any insights..

thanks and 73,
mike? n0mpm
Re: Faulty Progrock2 - no response to ticket #progrock2

 

Steve,

My Progrock2 initially ran very hot. I was able to connect via PC to the microUSB port and set the frequency, but at high frequencies (above 135MHz) the output becomes unstable/noisy and gives no output from 150MHz upwards.

Peter
Re: CAT script for setting the real-time clock

 

The QMX firmware version1_00_015 and up implement the?CAT command TM for get/set of real time clock.
I created a small powershell script for windows to set the time (see?).

73 Stephan HB9CHM
Re: QMX Case Fit

 

Good morning (In the States) Hans!

I used a little 'Burt' force, and by alternating screws from each side and opposing corners i got it together with a good fit.? Thanks, I was afraid to put too much pressure on it.? So far so good!? Just checked the receiver on 20 and it was receiving as strong as my FT-DX10.? Very excited!? Bands appear a bit dead so far today for 20.? Working through the configuration steps next and then the xmit!? A fun and challenging build and oh that wonderful feeling of completion!

Thanks,
Burt K4SRQ
Re: QMX Case Fit

 

I have had it happen before with other extruded aluminum boxes where the fit between the two halves is not perfect. I use a pair of smooth-jawed pliers to give a very (slight) bend in or outwards on one of the edges so the grooves would line up.

The two halves are made in the same facility but not as pairs. Usually the production line is good enough that a production worker could grab and upper and a lower out of the two big bins and package them together.

I use flat jawed pliers to keep from marring up the anodizing. You could also use a pair of pliers with heat-shrink or a couple of layers or tape over the jaws so the serrations do not scratch through the anodization.

--
Tisha, AA4HA
Re: QMX Case Fit

 

Hello Burt

Series they're slightly off and require a lot of force but I can't recall having seen an enclosure which wouldn't snap together given enough brute force. But if you need me to send you a new one please let me know.?

73 Hans G0UPL


On Sun, Mar 3, 2024, 3:36?PM Burt Wizeman <burt@...> wrote:
Got through the build, added the firmware, booted up the rig.? Now to fit the case on!? This has turned into the most difficult part of the build.? The tongue and grove are off by a very small fraction.? I at first thought it must be the boards, so I took them out and verified that nothing was sticking up or out, the nuts were aligned etc.? Then I went back to the case and the empty case would not fit together.? Maybe a 64th of an inch or some miniscule amount but it is not a fit.? Anyone else have this fit issue?? The case was not stressed in any way and removed just prior to install.

Thanks,
Burt
K4SRQ

QMX Case Fit

 

Got through the build, added the firmware, booted up the rig.? Now to fit the case on!? This has turned into the most difficult part of the build.? The tongue and grove are off by a very small fraction.? I at first thought it must be the boards, so I took them out and verified that nothing was sticking up or out, the nuts were aligned etc.? Then I went back to the case and the empty case would not fit together.? Maybe a 64th of an inch or some miniscule amount but it is not a fit.? Anyone else have this fit issue?? The case was not stressed in any way and removed just prior to install.

Thanks,
Burt
K4SRQ
Re: RF preamp for power amp - HF and 6 mtrs. Magic silicon does all.

 

Generally...

video/RF amplifiers are measured the same.

Power output (undistorted and t 1db comprssion)?
Power gain (also votlage gain)
Distortion IMD, IP3, harmonics
Noise, noise figure of the amplifier.

You can use voltage gain or power gain so long as the input and output load
impedance are known.? For power the common use standard is 50 ohms and
DBW? or DBM.? Votage gain is sometimes used as well and if the load
impedance is know the conversion is easy math.??

That is an opamp amplifier so gain is the ratio of the feedback plus or minus 1.
The latter parts sign reflects if the amplifier is inverting or noninverting.

The series output resistors are for stability as most opamps are rather fussy
about reactive loads.? Fussy translated to they become unstable or can oscillate.

--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
Re: High Band QDX One-Band-Low-Power Syndrome (yet again)

 

In testing per the video cited (scrunching L4 and L10's turns closer together), I was able to get the output up to 2-1/2 watts but that only made me more convinced -- as you said -- that the BPF is the major factor in this situation.
Yes, I did.? Perhaps my surmise above was incorrect. As I said before, I'm reluctant to butcher the radio when it operates perfectly well on 20m through 12m so far as power out is concerned -- and I am fine with 2W on 10m for the moment. I have a Low Band QDX coming and I will be more circumspect about winding L12 and the LPF coils on that.?

Dunno.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
Re: High Band QDX One-Band-Low-Power Syndrome (yet again)

 

William,

I count 20 turns on both of the toroid pictures.? The difference is on the 14th turn.? I count 15 turns to what should be the 14th turn and then only 2 turns between 17 and 20 on the second picture.

L12 will not impact the QDX output.? For 10 meters on a high band QDX, that is L4 and L10.? Have you tried squeezing or expanding those toroid windings?

73
Evan
AC9TU
Re: High Band QDX One-Band-Low-Power Syndrome (yet again)

 

Evan,

Thank you for your reply. I went back to carefully review my work as well as LY2H's video covering this subject..



After carefully inspecting L12, I believe it is one turn short between "17t" and "End (20t)". I am not sure that is apparent from the pictures I posted below but using magnifying eye glasses and a harsh light, it goes to the last turn being omitted. In testing per the video cited (scrunching L4 and L10's turns closer together), I was able to get the output up to 2-1/2 watts but that only made me more convinced -- as you said -- that the BPF is the major factor in this situation.

Interestingly, I will have to "work up the courage" to extract L12, rewind, and replace it. The other bands -- 20m through 12m -- put out a robust 4-6 watts* and I am loathe to turn the whole built rig into lunch meat for the sake of 10m. I may yet gain the nerve to do so, but my recent experience on 20m and 15m compels me to manufacture a 12m and 17m vertical and see what can I see.

..all of that said, I marvel at the technology and research that went into designing the radio, how Hans has brought fire from the Gods like Prometheus of old, and how wonderfully abundant this group is with knowledgeable hams as yourself to provide support.

Thank you again.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."

*which will be throttled back to about 5 watts by lowering the input voltage.



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