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I finally got around to building the version one QMX I purchased last year at FDIM.? The build went well and I thought I has no problems, but it appears to be weak on receive.

I have 4.95+ watts out on all five bands.? So it appears the transmit side is doing well.

On receive I have been able to make contacts using FT8 mode, but on CW receive I can barely hear anything.? Anything I do hear is weak on the QDX,? but strong on a nearby receiver.

Everything else seems to be working just fine.

My firmware version is 1.00_014.

The serial number of this unit is #62 so it was a very early unit purchased from Hans at QRP vendor night at FDIM.

Anyone have an Idea where the problem may be with my receive problem?

Gary A. - W0MNA

Besides being amused by the hard way approach, some thoughts.

The test transmitter has to put out the needed power on all bands
of interest.? ?Easier said than done for many.

I has to be robust, you are going to expose it to terrible SWR while the atu100 tunes.
Or course if it fails, your back up plan?? More important when in the field.

It must be efficient if portable as its using your field power.

IT should have switching to remove it out of line or you do a lot of cable swapping.

I'd suggest small.

Me I use a Zmatch with a bridge sensor and also power meter.

--
Allison
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Post online only,?
direct email will go to a bit bucket.

The downside of the connector is to degrade the heat flow through the leads - a major element of the heat sinking.

A couple of days ago I noticed power out dropped to 2W.? It took one hour to open the unit, separate the boards (I made extender cables to allow operation with separated boards) find the hot BS170, replace it and reassemble the QMX. I do have a vacuum de-soldering station that makes removal easy.

I built a QMX low band in the summer with no issues. So, I bought a high band kit for Christmas and after building it, I see nothing. No bootloader, no start, nothing on the display. Comparing the two, on the second build, there is nothing at all on the 3.3V rail, it draws about 8.5mA while pressing the left encoder to power up, then nothing when I release the button. Unwisely maybe, I tried substituting all the individual boards from the new build into the earlier main board, and everything works there, so it must be some sort of fault on the new main board. I can't see anyone else with this issue on the forum, has anyone else seen this? Advice welcomed, at the moment it's sitting there useless!

George, M0HLP

No clue why you would do this (I have much experience of sockets getting problematic over time) -? but enjoy . .?

hi
Forgot:

ATU-10 can tune less than a Watt.

73 de muhsin TA1MHS

Hi

Quick BS170 change

73 de muhsin TA1MHS

Sam, et al,
An SWR bridge will protect the transmitter, but it will NOT pass the full 5 W through to the ATU. Probably closer to half that. If the ATU truly needs 5 W, then this trick won't work.?
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73, Dan? NM3A
There are moments when everything turns out right .... Don't let them alarm you; they pass.?

-Jules Renard

Jim, a buck converter with current limiting sounds like a great idea for these QRP Labs radios!

Thanks Bruce. Good to know. from the schematic I could not see how I could have got it wrong.?

Onward and upward. :-)
--
regards,
Bryan, N0LUF

Hi

From the same designer of ATU-100 pls try ATU-10.

I'm using this tuner for a long time

perfect for QDX, QMX, 705, Hermes Lite 2 vs

73 de muhsin TA1MHS

?

I have used RF shield paint for some projects, but on the QCX, ?I had no issues - 3 mm particle board worked just fine. ??
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73, Bernie, VE3FWF

That's it Bernie! Thanks so much! BTW - I like your laser cut enclosure! Question - is it foil wrapped inside for RF/EMF? insulation? I've thought of using other materials for enclosures but wondered if they need to be so insulated.

Thanks again, I'm on it! Manual logging is for the birds!

Is the QMX assembled or still as a kit?

That's OK. They could just reply to you privately here by clicking Reply and then choosing sender:


73, Mike KK7ER

Even with 220K the contrast adjustment is super sensitive?

the centre holes are for the jumper or the outer holes for the resistor?

Looking at the pcb the top 2 holes are joined with a trace. the 3rd hole has a trace running off somewhere and the bottom hole, I can't tell. If it has a trace its on top side.

I tried using hole 2-3 and 2-4. either way a pretty sharp adjustment curve on the trimmer. I guess it is what it is and that's okay. So I'm moving on to other toys. maybe Ill add some temp sensors.?
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regards,
Bryan, N0LUF

Thank you everyone for the tips. I redid the solder on connection C on T507 and voila¡­ no more protection mode. Now to the diag fine tune.?

I appreciate all the support.?

73, Eduardo, KC8R

(Sorry, I meant to say IC402, not IC403.)