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Hi All, Just wanted share my experience with you. I have experimented with 3 electret mic capsules so far. 2 that I scrounged off of other boards and one utilising the mic from my PC gaming headset. The mic from the head set resulted in low volume and unsatisfactory modulation. When I turned up the mic gain on the QMX+, the QMX also amplified internal noise creating unacceptable background noise in the modulated output. The other two capsules were a little better but still unsatisfactory. One of the capsules that I had took off was from a MAX9814 Arduino mic amplifier module. I thought, "Hey, why not use the amplifier module to use with my headset!" Well, I did just that. I wired up 2 x 1.5v AA's in series to power the board with and wired the mic from the headset as the input to the amp. I then wired the output of the amp to the mic input of the QMX via a 1uF capacitor to block the 3.3v dc from the QMX. Well, that done the trick! I'm getting much better results now. But I did have to reduce the mic amp module gain as it was way too high. As it currently stands, I am unable to achieve a satisfactory calibration with any of the bands on my QMX+. As a result of this, my QMX+ is in default calibration settings. The mic gain on my QMX+ is now set at 35 and have made a few contacts with good reports with this setup. Now, the question is, how do I wire up the mic amp module to the QMX using the 3.3v supply on the TRS rather that using batteries? I did try taking the 3.3v via 2k ohm resistor from the QMX TRS terminal to the vdd of the mic amp module, and connect the output of the module back to the same TRS terminal via a 1uf dc blocking capacitor, but sadly that didn't work. I'm clearly missing something... Cheers, Mel. M0KMD.

I'm selling my QMX (Low Band). (80, 60, 40, 30 and 20 meter bands) Built for 12 volts but I have never supplied more than a little above 9 volts to it. I purchased it as a kit and after not being able to complete the first continuity test, I sent it to W1NC Jeff Moore who finished the build. It’s in excellent condition and I have used it in the shack and on a few POTA activations. I am including a printed copy of the manual. Also included is the GPS kit, assembled, which works very well. I’m selling because I recently added the QMX+ to my collection. Price is $135 which includes shipping to USA via priority mail. Sold as is. No returns and no warranty is expressed or implied. Payment via Venmo or PayPal to my email address which is up to date on QRZ.com. 73 N2JHR --Jim Rusert

Hello all, Long time lurker, first time poster here. I recently built a 60m-15m QMX and I am having some trouble getting good reception on 15m and 17m (see attached RF sweeps). I should mention that I am using a Rev 1 board purchased in 2023, but with a mid-band component kit from 2024. Here’s where I’m at: I get good power (4-5w at 12V) out on all bands, and my LPF sweeps look like the firmware manual 60m-20m RF sweeps look more or less like what’s shown in the manual. I use a QRP Labs 50 ohm dummy load for the sweeps. When I connect to an antenna, I can hear FT8 signals on 40m and 20, but not on 17 or 15 Because the lower bands seem to receive OK, I suspect an issue with L401a, C401 or C403. However, 20m uses L401a and C401 and is OK, but 17 also uses those and is not good. I reflowed solder on all 3 taps for L401a and the capacitors, with no change. I’m pretty confident I’ve burned off all the enamel at the junctions at this point. I get continuity at all the points shown in the Rev 1 manual (plus at pin 6 of IC402, which I think makes sense because I’m using all 4 connections for L401 instead of just the 3 with the low band version) I did a factory reset, with no change I’ve counted the number of turns on 401a more times than I’d care to admit, and keep coming up with the same number I’m supposed to have (24 turns, tapped at 15) I confirmed that C401 and C403 are the correct values printed on the component, and don’t appear to have any physical damage Trying to figure out my next steps, but coming up a bit short. All I can think of is to replace capacitors, and possibly re-wind L401a. Or, even less ideally, replace IC402. I don’t have an oscilloscope (or any real expertise to use one), so my ability to diagnose is somewhat limited. Before I start swapping out components, is there anything else I should try looking at? It’s been fun building this kit and I have managed to iron out quite a few kinks along the way by reading posts on this forum. However, this one has me stumped. Thanks in advance Alex, N7ADH

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