开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. QRPLabs
  2. Messages
Expanded Topics Messages Polls
Date
Re: Does the QMX need a mic preamp? #qmx #QMXplus #SSB Firmware beta 1_01_003 release #qmx #QMXplus #ssb

 

Mel,
The MAX9814 tries to draw 3mA so it pulls the output of the QMX to near ground since 3mAx2.2k=6.6V when only 3.3 v is available
Gary
W9TD
Re: Too Much Power #qrp #cw #qmx

 

The diode drop technique is adequate for safety with “12v” batteries that are closer to 14v fully charged, but my goal is equalize the power as close to 5W as possible, across all bands when the supply is actually 12v.
Re: Too Much Power #qrp #cw #qmx

 

Battery measures 12v “key up” and sags to 10v - 11v on “key down” depending on band selection.
Re: QMX+ T507 winding direction?

 

Thanks Russ! Fortunately the Internet Archive's "Wayback Machine" has an archive of that page:
?
?
Looks like a handy circuit. I may start using this in other projects.
?
Re: #qmx mid-band receive #qmx #troubleshooting

 

Those scans look nice.? You have gained at least 6dB on 15 and 17 - maybe more.?
Now to test it in practice and see if you notice the change.
Yes, there is some other 'gain' factor going on; something attenuating the signal on 15/17 apart from the BP filter.? I wish I knew what it was.
Stan KC7XE
Re: QMX+ loose some characters while sending stored messages #qmx #QMXp #QMXplus #troubleshooting

 

hi, sorry, today I'm not able to test ... will inform you soon... tnx so long
Udo DF4BJ?
Re: Too Much Power #qrp #cw #qmx

 

A fully charged 12 V battery is definitely not 12V
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

On Wed, Apr 9, 2025 at 11:27 AM, Steve M wrote:
I am finding that the setting for the "Tune %" under the Protection menu has no effect on the power output when using the Tune SWR function under the Hardware tests.
Steve, in my experiments, I found that when setting the "Tune %" in the protection menu, you have to exit fully from the menu system for that setting to take effect.? If I back out just one higher level and go to directly the Hardware test -> Tune SWR function, it does not take effect.? But if I exit the menu system after changing "Tune %", it functions properly, and adjusts the Tune SWR power as expected (and also the SWR sweep power).
?
Stan KC7XE
Re: Too Much Power #qrp #cw #qmx

 

开云体育

Hi Matt - just reduce your input voltage by adding some series diodes, rated at 2A or so.


Regards

Roger

8P6RX

On 09/04/2025 14:44, Matt - W6CSN via groups.io wrote:

The QMX mid-bander (60m thru 15m) is one of my primary radios for portable QRP operations for nearly a year now. The “problem” is that it puts out too much power in CW mode. Here are the numbers using a fully charged 12v battery into a 50 Ohm dummy load measured with an external watt meter:
?
60m - 6.1W
40m - 5.3W
30m - 5.1W
20m - 5.6W
17m - 4.5W
15m - 6.5W
?
QMX Firmware is 1.00.026
?
Question; with the amplitude modulation capability that exists to provide SSB, can the CW mode be enhanced with per band configurations that enable trimming the power down to 5.0W for “by-the-book” QRP and to also lessen any risk to the hardware resulting from power levels that exceed 5 watts.
?
I can also see a use case for an easily accessible CW power level “knob” for running QRPp without fiddling with the supply voltage.
?
72,
Matt
?
?
Re: Too Much Power #qrp #cw #qmx

 

The approach I used was adding a high current diode in the power line between the battery and the radio to drop the voltage and reduce the power output.
--
Steve KA0SM
Too Much Power #qrp #cw #qmx

 

The QMX mid-bander (60m thru 15m) is one of my primary radios for portable QRP operations for nearly a year now. The “problem” is that it puts out too much power in CW mode. Here are the numbers using a fully charged 12v battery into a 50 Ohm dummy load measured with an external watt meter:
?
60m - 6.1W
40m - 5.3W
30m - 5.1W
20m - 5.6W
17m - 4.5W
15m - 6.5W
?
QMX Firmware is 1.00.026
?
Question; with the amplitude modulation capability that exists to provide SSB, can the CW mode be enhanced with per band configurations that enable trimming the power down to 5.0W for “by-the-book” QRP and to also lessen any risk to the hardware resulting from power levels that exceed 5 watts.
?
I can also see a use case for an easily accessible CW power level “knob” for running QRPp without fiddling with the supply voltage.
?
72,
Matt
?
?
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

Possible Bug - I am not sure if this has been reported previously.? My apologies if this has already been discussed.

I am finding that the setting for the "Tune %" under the Protection menu has no effect on the power output when using the Tune SWR function under the Hardware tests.? I get 5 watts out regardless of the setting.? Also, if I change the protection setting, I will not see the change on the Tune SWR function until I do a power cycle.
?
I have also seen the issue that Peter AI7YN reported with the frequency in the Tune SWR screen not always reflecting the frequency the VFO was tuned to prior to entering Tune SWR mode.
?
--
Steve KA0SM
Re: #qmx mid-band receive #qmx #troubleshooting

 

Thanks Stan. I did not realize that the RF dB values are using a common offset. That means that the RX performance on 17 isn't that different between BPF1 and 0 - only about 3dB. I decided to try removing one more turn from 401a, and here are the results (after a few different attempts at bunching/spreading:
Looks basically the same to me. I did try a version with very close bunching of the turns, but that only gave me 1db more of peak at 15m and moved the top of the curve to the left of 21mhz. I am kind of surprised that the BPF shape and amplitude are relatively insensitive to the number of turns on L401a. Makes me think there might be some other factor at play that's driving the filter response. In any case, I think I'm ready to chalk this up to issues with using a Rev 1 board in a different manner than intended. Unless, of course, you and/or others on the forum have any ideas about how I could squeeze a bit more performance out of 15/17m receive. Either way I appreciate your help and the wealth of knowledge on this forum
?
Alex N7ADH
?
?
Re: Does the QMX need a mic preamp? #qmx #QMXplus #SSB Firmware beta 1_01_003 release #qmx #QMXplus #ssb

 

I did a comparison of the microphone input on two of my mid-band QMXs. I used the same microphone. The attached screen shoot shows how significantly higher the noise is on the second QMX.
?
73, Zrinko Ivan, 9A7AM

QMX br. 1 - noise.jpg
QMX no. 1 - dynamics.jpg
QMX no. 2 - noise.jpg
QMX no. 2 - dynamics.jpg

CW Practice / Rag Chew

 

开云体育


On 4/08/25 I had a CW practice / rag chew session on 30 meters. I worked three stations:
Date / Time Call Bnd Frequency Mode Power Rec Snt Name SPC# Comments Off
4/8/2025 14:14 W9TO 30 10.111 CW 50 559 559 Tom OH K3 at 50 watts 100 ft sloper doublet 14:28
4/8/2025 13:44 KC9HEK 30 10.112 CW 60 599 569 Brian NY K3 at 60 watts 100 ft sloper doublet 14:04
4/8/2025 12:54 NM1I 30 10.109 CW 50 579 559 Butch MA K3 at 50 watts 100 ft sloper doublet 13:37

Conditions were OK. 30 meters seemed to be better than what I have been experiencing on 20 . SSN = 167, SFI = 162, A = 13, K = 2.

My next CW practice session will be April 11 at 09:00 EDT / 13:00 UTC on 30 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 11 2025
Time - 09:00 EDT ?13:00 UTC
Band - 30 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: CW Filters

 

On Wed, 2025-04-09 at 15:56:32 +0300, Hans Summers via groups.io wrote:
What would be a simpler way of arranging it? I can alter it...
Hans and Braden,


I think I need to explain my proposal a little bit further to avoid
misunderstanding. I attach a PDF outlining the present design and my
alternative.

In the present design a BANDPASS filter is used, nominally with a center
around the sidetone frequency of 700 Hz. In my sketch it also includes
the Hilbert transform. I guess that the present filter is of order 10 or
so according to the graphs in the manual.

My proposal is to use ZERO BEAT of the received signal and use a LOWPASS
filter. To get similar performance as above, two filters (for I and Q)
of order 5 or so will be needed. The side tone is mixed after the filter
just in front of the DAC feeding the speaker/phones. An optional offset
(OF) can be added to adjust the center of the CW filter up and down.
This will mean two settings: bandwidth and center. These can be adjusted
independently.

The Goertzel algorithm can be replaced by an moving average to feed the
CW decoder.


Regards Anders

block.pdf
block.pdf

Re: QMX+ T507 winding direction?

 

There is some small interaction between the two windings on a binocular core which ultimately limits the directivity of the coupler, but it is not at all an issue for the QMX.

I would usually include a URL to Owen Duffy's website at this juncture, but sadly, it was shut down ?

72 de Russ, va3rr
Re: CW Filters

 

Hello Braden

What would be a simpler way of arranging it? I can alter it...?

73 Hans G0UPL



On Wed, Apr 9, 2025 at 3:29?PM Braden Glett via <bradenglett=[email protected]> wrote:
N2DI's video helps a lot, but overall my comment would be that the filter system is just needlessly complicated, at least from a CW operator perspective. Not sure about SSB or digital.?
Re: QMX+ T507 winding direction?

 

Thank you. I wasn't sure if there was interaction in the core between the two windings.
Re: CW Filters

 

N2DI's video helps a lot, but overall my comment would be that the filter system is just needlessly complicated, at least from a CW operator perspective. Not sure about SSB or digital.?
81 - 100 of 140795