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Re: #key #qmx QMX Straight Key Mode incorrect #key #qmx

 

First time installment of a firmware on a new QMX (no EEPROM file) will not initalize all menu settings correctly. In the menu the keyer setting defaults to straight and tip.
Change it to to e.g. iambic a and ring and leave the menu. Then reenter the menu and revert the keyer setting back to straight and tip.
HTH Gottfried
VIFLY ShortSaver V2

 

If you're interested in ordering the?VIFLY ShortSaver you might as well order them directly from China via AliExpress and save some money. I ordered some from?VIFLY Drone thinking that I was helping a small business and would get them in a timely manner. Well after a week I finally got an order confirmation and that they were being shipped from China. A couple more weeks have passed and I still haven't gotten them. They have at least gotten through customs!

Roy
WA0YMH?
Re: QRPp

 

How about just using an attenuator with a bypass for receiving? QRPGuys have one for 25 dollars or so.?

Don Meyerhoff WA2SWX?

On Tue, Feb 27, 2024, 6:18?AM <wb2cba@...> wrote:
Easiest way is to remove 2x BS170 and run on one BS170. Then you will in QRPp range.
--
?

73, Barb, WB2CBA
Re: #qmx filter testing and adjustment #qmx

 

Oh, yes, that was a nice trick.? I figured out the problem with 15m is that the cutoff frequency is too low, and 21.074 MHz is actually more than 3dB down.? I did the transmitter test at 19MHz, well inside the passband, and got 4W.? So I need to tweak the toroid to push the cutoff frequency up.? The same might also be true, to a lesser extent, on 12m and 10m.

Eric
Re: Wall Wart Tests

 

I accidentally plugged in a 26v supply from another ongoing project. Do you suspect I'm ok after replacing the SMPS boards or is this disaster likely more serious?
Re: QMX: C516 - C525 swapped value #qmx

 

Thank you very much for the information.
Now I can proceed with the assembly with peace of mind.
Re: #qmx wrong inductances for LPF? #qmx

 

On Tue, Feb 27, 2024 at 08:20 AM, @Ludwig_DH8WN wrote:
Please be aware of the different stray capacitance and the capacity of the connected QDX circuits. And use a rf suitable board!!!

My final result of my whole testing was: Following the manual brings good results or at least a good start point to tweak the filters.

Thank you for your thoughts and clarifications!

The more I play in Elsie with LPF simulations, the more I agree that following the manual will be a good start. It seems in the QDX HB, the 15/17m LPF is the most sensitive to the inductance values. The others are more...robust. Especially as far as reflected power to the PA. And there are more downsides to using less turns on the 15/17 than the recommended number of turns, even if inductance is higher than spec'd/calculated. So I will follow the manual pretty closely, maybe doing 20T instead of 21 on L2, but that's the only change.?

-Nate?
N8BTR
Re: QMX: C516 - C525 swapped value #qmx

 

On 27/02/2024 15:45, jh4vaj wrote:
t appears that the values of C516 and C525 are swapped between the schematic and the manual.

"The current assembly manual is correct: C525 is 270pF and C516 is 180pF. "

Be careful, simulations must account for stray capacitances.

73 Alan G4ZFQ
QMX: C516 - C525 swapped value #qmx

 

?
On the QMX rev.2 PCB, it appears that the values of C516 and C525 are swapped between the schematic and the manual.
I have run simulations and the values in the schematic seem to be better.
What do you think?
Re: QMX v3 rev017 Digital Modes Receive Gain Low

 

You can adjust input gain in the terminal configuration menus.
73
--
David Thomas M0OOR
Re: QRPp

 

?? I agree!
--
?

73, Barb
Re: QRPp

 

You are right Hans! I forgot to mention the most important point! I lower voltage to 5V! Getting old!! Sorry for the snafu!

ROFL... and we can celebrate this fine Tuesday with one less mystery to worry about!

73 Hans G0UPL
Re: Faulty Progrock2 - no response to ticket #progrock2

 

I have used numerous ProgRock2's without any problems -- I install them in old receivers and transmitters to replace faulty/drifted crystal-based heterodyne oscillators.? What are you trying to do and what went wrong?? Possibly I can help.

73 - Steve, KW4H
Re: #qmx filter testing and adjustment #qmx

 

Did you made the output transformer in the WSTS style?

73, Ludwig
Re: #qmx wrong inductances for LPF? #qmx

 

Hi Nate


On Mon, Feb 26, 2024 at 07:43 PM, <natereik@...> wrote:
? ? Am I understanding that you were finding T37-17s to measure 25%+ high when you wound them??
And your further work with T37-10s is validating your measurements?
From Material 17 I used the size 30 (T30-17).
Validation by using T37-10 showed two things:
1. My setup brought probably to high values for L.
2. Despite the deviance (see No 1) the AL of the T30-17 (QMX) could be probably a little bit to high but probably not +25% or more.

With 12 turns on a T37-17, I was somewhere around 0.35uH. Taking it all the way down to 8 turns got me 0.22 ?H
These values are not consistent. Reducing from 12 turns to 8 should reduce the inductivity by theory from 0.35 ?H to 0.16 ?H (not the measured 0.22 ?H).
Did you use the same allocation of turns across the toroid?

I'm considering building a whole LPF on a breadboard
Please be aware of the different stray capacitance and the capacity of the connected QDX circuits. And use a rf suitable board!!!

My final result of my whole testing was: Following the manual brings good results or at least a good start point to tweak the filters.

73 Ludwig
Re: QRPp

 

You are right Hans! I forgot to mention the most important point! I lower voltage to 5V! Getting old!! Sorry for the snafu!
--
?

73, Barb
Re: QRPp

 

Hello Barb?

?I have QCX V1 and I adapted for usdx and used it with 1x BS170 without any problems many months. The PA efficiency is 60 to 70% which does not create significant excess heat.

The maximum power dissipation of a BS170 according to the ON Semi datasheet (these are the devices we supply) is 0.83 Watts.?

If a QCX was producing 5W output at 60% efficiency the heat dissipation would be 3.33W. Rather a lot for one BS170 rated 0.83W. I'd be surprised if the BS170 could handle such a thing...?

So I'm not sure what is going on there... something sounds not quite?right to me. I'd expect the output power would be somewhat reduced because the "ON" resistance is 3x what it would be with three BS170 in parallel. However I'd expect the power reduction to be relatively modest; the output power wouldn't be reduced to 1/3 of its three-transistor value...?

So I'm at a loss to explain the survival of your BS170 but all power to it! (err, literally)
?
73 Hans G0UPL
Re: QRPp

 

Hans,

?I have QCX V1 and I adapted for usdx and used it with 1x BS170 without any problems many months. The PA efficiency is 60 to 70% which does not create significant excess heat.

?Actually that QCX is my QRPp rig which I still enjoy. I know that usdx is not the QCX firmware though I think they share the same QCX ghetto class E PA design regardless of firmware as hardware topology.

I like to experiment and this suggestion was through my experiments that I carried out so ?here is the disclaimer listen to Hans and do not try this at home if you are not into experimental ham radio operation!:)
--
?

73, Barb
Re: QMX Diagnostic Power Out Vs Meter

 

Wrongly wound SWR transformer?


On Tue, Feb 27, 2024 at 1:53?PM bcharbour78 via <bcharbour78=[email protected]> wrote:
I've got a homebrew QRP power meter (photo of schematic) and it showed 17.7v (+3w) in my DVM.? That's quite a bit more than <.5w!? I'm gonna go back and reflow the toroids and transformers.? Maybe that'll show a better power out reading in the diagnostics.


--
Bill Harbour
K4VIB

Re: QMX if Vaudeville Still Existed

 

Abbott & Costello did a great variation on it using "Susquehanna Hat Company" as the trigger phrase.
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