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Power out on 60 mtr QCX+

 

Hi
I recently built a QCX+ for 60 mtrs. Everything works ok except that I only get about 1.5watts out into a dummy. load.? Just wondering whether any one has built a QCX+ for 60mtrs and what power? out? that is expected for this band .
look forward to any replies.
Keith G4TJE
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CW Practice / Rag Chew Session

 

¿ªÔÆÌåÓý


On 4/12/25 I had a CW practice / rag chew session on 30 meters. I worked one station on 30 then switched to 17 and worked one station there:

Conditions started out OK on 30 but after an hour it went dead. I switched to 17 which seemed better but still not much action. SSN = 114, SFI = 157, A = 20, K = 2.

My next CW practice session will be April 21 at 09:00 EDT / 13:00 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 20 2025

Time - 09:00 EDT? 13:00 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

Re: QMX with POTA Yesterday

 

Nice description Jason.
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Can you detail or link the diode fix please?
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Thanks
Re: QMX+ with WA3TFS amplifier

 

Allison, thank you, I will do that.? I had removing C17 on my list to test, but didn't try it.? I mistakenly thought that once PTT triggered the relay, it was a non-issue.? I see now that leaving C17 is a problem.
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Early on I tested +5V to R6 without RF in and the current was stable at 1mA.? With RF in, the current was much larger and unstable, I guess due to the rectified RF!?
--
73,
Jim - AE5JE
Re: QMX issues

 

Intersting name. I don't see many "day's".
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73.
Jerry/k5sop
Re: What do I check when QMX transmit stops working?

 

Have you Enabled TX PTT in PuTTy? If not here are the steps to do so.
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  1. Navigate to the QMX Menu:?Access the QMX putty menu using the appropriate method for your QMX device (e.g., using the on-board keys or a connected computer).
  2. Locate the "Transmit" Setting:?Within the menu, find the setting labeled "Transmit".
  3. Enable Transmit:?Press the "E" key to enable transmission for the selected band.?This allows you to transmit on the chosen band.
  4. Locate the "TX PTT +5V" Setting:?In the same menu, find the option labeled "TX PTT +5V".
  5. Enable PTT +5V:?Press the "E" key to enable the +5V signal on the PTT connector during transmission.?This provides the necessary signal to activate the transmitter.
  6. Verify Settings:?Double-check that both "Transmit" and "TX PTT +5V" are enabled for your desired band to ensure proper operation.?.
Re: QMX only hearing static

 

Kai, please don't apologise. No duty for a fast reaction, it's our hobby.
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Your result points more to a broken PCM1804. It's the highest probability. But to exclude something more you may test this:
  1. Check voltage at IC403 pin 2 and pin 14 to GND. Both should show around 1.6V (pulses with 3.3V high and 50% duty cycle.) But take care not to connect these pins to others. You may destroy IC204. And it's hard to have access to IC403. If you don't want to check these voltages, no problem. If the TX is working there is a high probability the two signals are ok.
  2. Check voltages at IC405 and IC406 pins 1, 2, 3, 5, 6 and 7 to GND. For all you should see something around 2.5V.
If you don't want to replace the PCM1804 by yourselves you may contact Jeff Moore (please check th forum for his name).
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I wish you success. 73 Ludwig
Newly assembled QMX, SWR=1.5 with dummy load

 

Hey,
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I just assembled this a few days ago, made a couple of contacts with an end-fed. What I found odd is that when I attached a 50 ohm dummy load to the output and measured SWR, it was around 1.5 on 20m and <2 on other bands. Surely it shouldn't be that? What may have I done wrong? Should I worry?
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73 de HF2J
Re: QMX issues

 

On Sun, Apr 20, 2025 at 01:47 PM, N4REE - Bob wrote:
Probably because the op fiddled long enough to draw the voltage down to an acceptable value.
12V and a bit more is no problem for a 9V QMX except the PA. So if you operate from 11.xV without transmitting there will be no problem. And there will be nothing like written in the first post.
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No sidetone could be a result from protection because of a (short) high SWR. Factory reset will reset the protection status but every time and not only after some resets.
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But what should cause "No audio out"? The audio is switched off in some parts of the menu. But you should see this if watching the display. And I don't know why it should be off in normal RX status and "repaired" by a factory reset. (Ok, if you lower the volume to zero it will be at default after a Factory reset, but default after the first Factory reset.)
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All this looks to me more like a wiggly contact. After pressing buttons sometimes it's ok and sometimes not.
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73 Ludwig
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Re: QMX+ Front Panel Soldering - Alternate Method

 

I followed the instructions explicitly since it was my first build. And I felt like this was indeed one of the tough points to accomplish.
Being new to soldering added to my anxiety of course.
I kinda felt like I was building a ship in a bottle.
But thankfully, even without the ¡®tricks¡¯ of the experience builders above.. I was still able to prevail.. and without issue.
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My new QMX+ is ¡®on the air¡¯!!!
Happy Easter everyone!
Mike
KK7MMN
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Re: Thank you Hans

 

Me too. I've often posted how satisfied I am with a self-built, QMX high band. Over a thousand POTA hunting QSOs with it now, and reach as far as Alaska and mid-Germany from central Florida (with simple antennae).? Just finished building the QMX+ last week and have put about 100 QSOs on it. BOTH are fabulous radios! Thanks Hans!
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72 de N4REE, Bob Easton - QRP CW forever
Re: QMX #12v

 

The Assembly manual clearly states that the PCB board is the heatsink, not the washer.
I've been using a self-built high band, 12v, QMX, in our Florida heat, for many months and have never felt it hot, or even warm to touch. NOT a problem!
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OTOH, I don't do .
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72 de N4REE, Bob Easton - QRP CW forever
Re: QMX+ not measuring SWR

 

Sorry for this jumbled stream,? I will make a proper post with screenshots later today. Thank you so much for the help.


On Sat, Apr 19, 2025, 7:54?PM Nico Smith via <nicosmith873=[email protected]> wrote:

What parts should I check for rx? Also now for some reason it says swr is 1.7 on every band when it is not


On Sat, Apr 19, 2025, 1:34?PM DH8WN via <DH8WN=[email protected]> wrote:
Nico,
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to transmit you use the TX path and for receive the RX path. If one is ok it doesn't mean the other must be ok also.
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73 Ludwig
Re: QMX+ Front Panel Soldering - Alternate Method

 

I used this method as well, assemble the display, connecting pins and front panel using the top two screws with nut spacers. Solder just the front pins to the display.? Then disassemble and follow the instructions, except that the front pins with the poor access are done.
Re: QMX issues

 

On Sat, Apr 19, 2025 at 08:27 PM, Stan Dye wrote:
I'm not sure why a bunch of Factory Resets fixed it.
Probably because the op fiddled long enough to draw the voltage down to an acceptable value.
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Y-O-Y did Han's waste so much time putting multiple LARGE PRINT, red font, voltage warnings in the manuals?? ;)
--
72 de N4REE, Bob Easton - QRP CW forever
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

For information, with the Windows volume all 100% as well as the Vara sound card (change has no effect) my 20m VarAC output is 2.5W.? That is 1/2 of WSJTX output.
Re: QMX+ Front Panel Soldering - Alternate Method

 

My approach was to use the method described in Hans' instructions for the 2 corner pins. That was enough to establish position. Then, I loosened the screws just enough to allow the assembly to tilt back about 1/4 inch. That gave enough room to make the rest easier ... and without letting the spacers escape.
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72 de N4REE, Bob Easton - QRP CW forever
Re: Liner Operation of QCX 50w Amp

 

I think you should buy some (maybe a box of ? ) transistors and a bigger heatsink and some plain board and read up and start from there?
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When messing with input stages ?you¡¯ll find the input impedance all over the place (hence the pi attenuator input)
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When messing with output stages the dissipation will increase and the impedance varies with the point in the cycle (so the LPF action is degraded) and remember the 50W amp has never been wideband?
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Remember the interesting way Hans avoided RF feedback at switching points by boosting the switching diode bias from the RF waveform - that probably needs checking ?too
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Re: Liner Operation of QCX 50w Amp

 

The QRPLabs 10W linear amps and the 50W non linear amps seem to have very similar output circuitry. I am awaiting delivery of my QMX+ but I also have had for a long time one of the 10W linear amps (bought in anticipation of the QSX) that I want to use. My question is¡­if I removed the BS170 drivers in the 10W linear amp and added a smallish input matching attenuator would the gain be sufficiently reduced so it could be driven linearly from say a 1-2W drive from the QMX? I am really only interested in the SSB output at the higher frequencies i.e 10m and 6m and beyond, as I noticed reports of quite low powers reported generally from the QMX+ at these frequencies.
I was proposing feeding the output of the 10W amp back through the QMX+ LPFs as the old LPF modules were rated at 10W so I don¡¯t see why the QMX+ should not handle the same. I was even considering changing the IRF PA devices for the higher frequency version used in the 5W amp (did this and got it working on 70MHz fine).
wadderya think?
73 Ken G4apb?
Re: QMX+ Front Panel Soldering - Alternate Method

 

I¡¯ve built two QMX+ and used this method to solder the display.
It adds probably 15 minutes to the build time, with the pre-assembly and disassembly, but so much easier to solder!
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