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Hi All, I have a plan to build a QDX-M for 80 metre FSQ activities. The QDX-M appears to be ideal for this with it's clever non SSB method of producing the tones required. However, the web page shop only lists 10,11,12 metre bands at the moment. After looking at the circuits for the QDX and QDX-M the changes for 80 metres would seem to be: 1. Use the low pass filter design for 80 m from the QDX. i.e change the inductors and capacitors in the QDX-M to be the same as the 80 m filter in the QDX. 2. Change the inductor in the QDX-M (L12) so that it resonates with the 56 pF capacitor at 3.6 MHz. 3. It looks like L14 remains the same for all bands. So my question is: Has anyone done this and are there any steps I've missed, and can I buy a QDX-M kit with all the appropriate toroids, inductors, and capacitors? I'd like to buy one QDX-M for 80 metres and one extra set of components to change the unbuilt 10 metre QDX-M I have to 80 metres. Apologies for the long and involved post. Best Regards Richard Katsch VK2EIK

Please see: https://www.qrz.com/db/KR4DID 72, Bill, N4QA//QRP on the mountain in Roanoke County, Virginia.

We had six folks join the MI QRP Zoom Chat on 17 April. Please join us Thursday April 24 (and every Thursday) at 4PM Eastern for the Michigan QRP Club weekly QRP Chat where the main topics will be QRP and other ham interests. New hams are encouraged to participate and ask questions. It's fun, it's easy, and it's free. You only need a computer, a smart phone, or a tablet that can connect to the Internet. OR if you can't be close to any of those you can join by audio with any standard phone. Just follow the directions below. No software needs to be loaded or installed. Anyone can join and non members are welcome. Details are here: https://www.miqrp.net/zoom Zoom ID: 811 0835 6229 The topic for Thursday, 24 April will be an OPEN FORUM. Pete WK8S Ed AB8DF Ernie N3ETE Tony W8CDC Stan WB8QJZ Casey KC9IH The bands have been crummy lately. TAXES! Pete is getting an old National five tube receiver. The weather is improving and we are all getting antsy to do some POTA. Stan is still playing with SSTV and the ISS. He had a good pass yesterday but got sidetracked with a ham radio zoom meeting. Another satellite starts in a couple of days so he may try it. He is also working on the DMR Net Michigan One Net https://www.michiganonedmr.net. This sounds very interesting and several of us will be checking it out. Tony is still trying to fix his TenTec. Ed got some color burst crystals to bring to Hamvention and the Michigan Mighty Mite Revival at club night. He also got some non inductive 250 watt resistors. He will build a high power dummy load with them. Pete is working with his Zbitx https://www.hfsignals.com/index.php/zbitx/. The recent firmware updates have improved the rigs performance. Need to look at 40 meters for the CW practice sessions and maybe even for the clubs net. We talked about the FCC issuing callsigns to stations and the ability to get a call sign outside of the station's area. Like a Michigan station being able to get a AB6XX callsign. We talked about tariffs and what they may mean for us QRPers. We are all in a wait and see mode on the tariffs. Pete is trying multiple elevated radials with POTA verticals. He is also looking at towers including a ALM-31 - US Tower. The agenda for the 24 April QRP Chat: Ernie to do a short introduction and acknowledge any new folks to the Zoom chat. The topic for next week will be an open forum. During the open forum anyone can take the floor. We will go one by one until all have had a chance to have the floor. Files, pictures and presentations can be shared if you have any. Please try to stay muted when someone has the floor. Thanks Ed AB8DF

What band is this?

This one has a QRP focus. https://www.qrparci.org/resource/FDIM81.pdf Ed AB8DF

Hi all, Having real struggles to find an existing cover(s) for the QMX+. All the ones are see are for the QMX. I can model some up easy enough but looking for a 3D model of a the QMX+ itself to model these around. I could model something close enough but looking to save some time. Thanks Colin

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

Hey, 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? 73 de HF2J

I have recently seen unstable 1pps on my QLG2, used for a GPSDO The QLG2 has a minimum of 10 fixes, tracking 17 vehicles and signal strength 35 - 40 on an external mushroom aerial. The 1pps suddenly jumps to a slightly shorter perid than 1s that throws the PSDO into holdover. Has anyone else seen this behaviour? Is it a duff GPS engine. Could it be a software glitch in the QLG2 ? Ideas on a $5 bill :-) 73 Mike

I plugged my Heil Pro 7 (IC) with AD-1-IC into my QMX+ with version 1_01_003 Firmware. I adjusted the mic gain with the hardware test from my PC and later from the QMX. I made my first contact with a POTA station in Houston from Colorado on 20m, with difficulty because of my weak signal. Although I have tried, I have yet to make any additional contacts on 20m. I plugged the Ad-1 stereo earphone connector directly into the QMX, but had to use a stereo splitter to isolate the ring and ground connections. While the ICOM radios like the 7610 supplies an 8 volt bias and the QMX 3.3 volt bias, the Pro 7 IC seems to work OK with the QMX. I use VOX. Using a Li-ion battery to power the QMX, I plan to drive over to a ham buddy who knows my voice and make further audio adjustments and check the transmitted signal quality. I will post my settings here after doing so.

I started having problems with my QMX+ ver 1 after the SSB calibration. I ended up replacing the BS170s in the final amp which got me back to full power. However, I noticed that the power was not reducing in SWR test mode like it should. I determined that the power modulation transistor Q507 had probably failed. I replaced Q507 with a new transistor, but the QMX+ did not survive the operation. I am now unable to get the QMX+ to power up. I suspect that I damaged the board when I removed the old transistor and now have a short to ground on the board under the transistor. Is there hope of bringing this QMX+ back to life, or is it time for a new main board? -- Steve KA0SM

hi, may i`m wrong with some qmx+ config, but sending cw from stored messages isn?t possible without loosing some characters, as like as "cq de df4bj" may ends in "ca de dfuba" or something else. Same behavior if sending from logging programm via cat. Did i don`t have correct configs or is that an known issue? I have installed the v1_01_003, updated from 1_00_027 on QMX+ Rev 3 , but going back to a non ssb fw doesn`t help. any suggestions ? vy 72/73 de Udo DF4BJ /qrp

My QMX Plus is approximately 25% down on the Test Certificate power, so I am looking to replace one of the BS170 FETs. The Farnell catalogue has many different suffixes to their BS170 devices. Should I select a particular device?

Has anyone found a custom case for this buck/boost converter please? (Or models with the same dimension) https://www.amazon.com/dp/B09B1ZTJYC/?coliid=IKGW47Q0Z26DN&colid=DXYXF6H7A290&ref_=list_c_wl_lv_ov_lig_dp_it&th=1 (I don't have a 3D printer) Thanks

I recently purchased this microphone kit from Pacific Antennas https://www.qrpkits.com/microphone.html for $15. The kit was easy to build and seems to work ok with the QMX+ usng a MIC Gain set at 50. Anyway I made my first SSB contact today on 10m so I'm satisfied. I've enjoyed reading about what others are trying and look forward experimenting some more. Les, N1SV

Hell forum, please your help, I am building my QMX+ V3. On page 30 of the assembly instructions, there is a table were L518 is 268nH with 23 turns on the pink T37-0 core. This one turn less than L516 (435nH) with the same core. Measuring with the nanoVNA, L518 with 23 inductance is about 100nH higher. To reach the 268nH, I have to reduce multiple turns. So here goes my question: Should I keep undoing turns until I reach the 268nH or should I ignore the nano VNA and keep the 23 turns? The same applies to L517, were the number of turns seams high for the target 316nH. The previous coils were very close to the target inductance. Thank you for your help, Luis CU2IJ