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VARA Rise/Fall Threshold Changes Affect JS8? 3
KJ7RBS (I think) did yeoman's work in getting the QDX to work with VARA. He suggested setting: Rise Threshold to 65 (default 80) Fall Threshold to 45 (default 60) Min. Samples to 120 (default 480) Two questions: 1. Has anyone tried these Vara compatible settings with JS8? I will if no one has. 2. Is there a way to change these parameters other than running Putty to make the changes in the QDX Configuration application? It'd be nice to just run a script that tells the QDX what parameters to change. Best, Jim K8DDV
Started by Jim Dolson @ · Most recent @
QMX Low Band For SALE
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
Started by Jim Rusert @
#qmx mid-band receive 8 #qmx #troubleshooting
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
Started by Alex N7ADH @ · Most recent @
CW Practice / Rag Chew
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
Started by Ed Kwik @
QMX+ Power Amplifier 5
Hello all, Last week I finished the build of a rev1 QMX+. No problems were encountered and it worked fine on powering up. During the build, I have measured the frequency response of the low pass filters.These appeared to agree very well with a simulation carried out with help of RFsim99. One anomaly was encountered: the series resonance of L507, a RFC feeding DC to the centre of the 60M-80M low pass filter caused an additional loss of about 0.5 dB just in the 60M band. To get rid of it the Q of the RFC was lowered by mounting a 2K2 SMD resistor in parallel of L507. I have been reading that many builders experienced a drop in output power on the higher bands and my build was no exception. As I like tinkering a lot, this appeared to be a nice challenge to see if this 'issue' could be improved upon. My build is for a supply voltage of 9V. Reading up on this issue on this list, it appears that the output transformer L501 is critical. Muhsin, TA1MHS, wrote that he had replaced the BN43-202 binocular core with a BN-61-202 core, which improved performance on the higher bands. Apparently a lower inductance for L501 helps. I did not have stock of a BN-61-202 core, but I had a BN-43-302 at hand and wound a WTST on it for 9V operation. The change in output power was negligible, though. The next thing I tried was using 2 x 3 BS170 instead of 2 x 2. Powered with 10V, gave these results: Band PWR-W I-mA 160 6.55 1150 80 5.35 928 60 4.99 925 40 5.73 975 30 5.68 1363 20 4.86 931 17 3.57 1258 15 5.73 1613 12 3.89 1553 10 5.05 1282 6 3.87 1080 This more or less solves this issue for me, though I don't think this is recommended in actual operating. I wonder what the reason is for the much higher current consumption on e.g. 15M compared to 80M, whilst delivering about the same power? A matter of lower impedance? Anyway, this is great fun. To be continued. Test gear: Sensor Monitor Power Meter 100W dummy-load Rigol DSA-815-TG spectrum analyzer Lab power supply 0-32V 2A 73, Roelof, pa0rdt -- Roelof Bakker, pa0rdt
Started by Roelof Bakker @ · Most recent @
Thank you 2
Stan, Ludwig, Dan, Jeff and all the others, whose names I cannot remember at this moment, for all your time and effort in volunteering to help others... And of course Hans, for designing and providing such an excellent product at such low cost. You are all invaluable gems that give us hope in this rotten world. 73! de Bekir TA2RX
Started by ta2rx bekir @ · Most recent @
FT8TW (Android) - a FT8CN fork - QDX/QMX and pskreporter working.
Hi https://github.com/danleetw/FT8TW https://github.com/danleetw/FT8TW/releases 73 DE muhsin TA1MHS
Started by Muhsin TA1MHS @
New Chat: Second order #chat-notice
A new chat has been created: Is it possible while my order is not shipped (assembled QMX+): to order dummy load and no to pay for delivering it with QMX+ together? By: Algis Unknown <wiseacre1@...> View/Join This Chat Do not reply to this message to post to the chat. You can participate in chats only through the group's website.
Started by Group Notification @
QMX Feature Request 16 #building #qmx #QMXplus
Gents, Just finished build of QMX+. Everything works perfectly from first power-up. Glad I watched Hans' video. The 6-layer board really does take a lot of heat to solder properly. Power is a little low - about 3W on most bands, compared to 4W from my QMX but that doesn't make much difference. One feature would be handy... I find that the QMX goes into SWR protection before my ATU10 has a chance to tune. I have to manually turn off protection when I want to tune a new antenna and/or band. How about when turning keyer speed to zero, in addition to going to straight key, set power to 50% and turn off SWR protection. 73, Glen W6GJB
Started by glen.brown10 @ · Most recent @
Pulse modulation on QLG2 / progrock output frequencies 2
I am using a GPS QLG2 to supply 1 second pulses to a progrock, the progrock is generating 27Mhz for a AD4351 DDS and 24Mhz for a receive function. On both the signals generated there is a "blip" when the 1pps fires, I have removed the bright green external LED I am using to no avail, also there is no modulating pulse if the GPS is not locked. This may be an old problem, any help appreciated 73 Dave
Started by Dave Crook @ · Most recent @
beta 1_01_003 FW strange behaviors 2
I just got back from the Pacific NW robotics district championships where N7BIN and team were competing. There are a couple parks just off the highway near Spokane so took time for POTA on the way to/from. I noticed a couple strange things with the 1_01_003 firmware on my QMX rev 2. At one point, after powering down to swap cables, the display showed USB mode but the rig was clearly in LSB mode. I switched to LSB on 20m and everything sounded normal again. It appears that there is some way for the displayed mode and actual mode to get out of sync. When in SSB mode, I noticed that the SWR meter was swinging wildly into territory where SWR protection should have tripped, but SWR protection did not trip. When in CW mode, it behaved as expected. This was transmitting through a ZM-2 tuner adjusted for 1:1 SWR. Despite this, and the challenge of 5W SSB with a low antenna, the activations were still a lot of fun. 73, Mike KK7ER
Started by Mike KK7ER @ · Most recent @
QMX+ points A continuity check to ground question 4
On p25 of the Rev 3 QMX+ manual, there is a check for continuity to ground from three points A. BEFORE installing T501, when checking the three points A, I get about 15 ohms with the DMM black lead on the ground connection, but open circuit (desired) with the leads reversed (ie red lead on the ground connection). Is this to be expected? The 4 BS170's ARE installed. I am troubleshooting a continuity check problem identified after having installed T501 (now removed). Thanks Steve AK0M
Started by Steve Sutterer AK0M @ · Most recent @
New Chat: QMX Bricked #chat-notice
A new chat has been created: I have been enjoying the 10-20m QMX for several weeks. I used two 1N4001 diodes to drop the voltage to about 10.5V. I had a beacon set on 10m. Antenna SWR was 1.2. Everything worked great until today. The diodes melted and the QMX is dead. I took the unit out of the case but there was no visible damage. HELP! By: w8mv@... View/Join This Chat Do not reply to this message to post to the chat. You can participate in chats only through the group's website.
Started by Group Notification @
QMX hiband for sale
Factory built 12 volts, works perfectly. I've only made a few hundred CW QSOs. -27 firmware installed. With case $165 plus postage from Japan. JS6TMW
Started by Steve in Okinawa @
QMX Build Challange 5
I received a QMX and built it. I've built a number of QRP kits all successfully, but not so for this little guy. I attempted to powered up using a regulated power supply at 7v and 250 mA but without success. In my efforts to get things going, I resoldered every joint and inspected for bridging. In the end, I clearly identified a component (Q109) on the 3v power supply that had a hole melted through the package. I've just order the spare power supply boards from QRP Labs, but don't know where to look for the cause of the current failure before installing and destroying another 3v power supply. Any ideas for me. Regards, Wilson Little (NT5AT)
Started by NT5AT - Wilson @ · Most recent @
QMX+ bias current + output power fluctuating 21
My QMX+ went together really nicely, along with my battery and speaker mods. However, the bias current is varying wildly on TX, also transmitter voltage is indicating low and output power varies. All other tests and sweeps look ok. I've attached a short video showing the diagnostics test on TX. I've replaced C504 as has been suggested and reflowed all joints that looked like they might be dry. I'm a bit stuck now on what the issue might be - any thoughts from the hive mind?
Started by ZL1SGS @ · Most recent @
New Chat: QMX+ assembled 2 #chat-notice
A new chat has been created: Hello, i'm sorry for asking newbie-easy questions. Do i need dummy load, perform any possible calibrations if will receive already assembled and tested QMX+? Can i use built in SWR sweep and meter for tuning my antenna? I'll use it mostly for digimodes. By: Algis Unknown <wiseacre1@...> View/Join This Chat Do not reply to this message to post to the chat. You can participate in chats only through the group's website.
Started by Group Notification @ · Most recent @
Release of version 2.0 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp) 29 #PSU #QMXplus #audio #ABS #ATU
Hi, I have released a version 2 of ABS solution. Please refer to the readme front page file at the git repository for full details and release notes: https://github.com/AC8L/QMX_Plus_Autotuner_Internal_Battery_Speaker/ The release includes new PCB fabrication files, BOM and detailed build instructions. This release took into consideration lessons learned and a feedback from first group buy participants fearlessly organized by Cal (AD8Q) and Stan (KC7XE). -- 73, Sardar (AC8L, 4K6SA, VA3DUA).
Started by Sardar (AC8L) @ · Most recent @
QMX snags epic DX during greyline! 3
Well the QMX masterpiece has pulled off the greatest miles per watt of my life, using my homebrew EFHW. I am still is awe to put it mildly. I worked FR8UA at greyline from Montana for a distance of 10,583 miles on FT8. Thank you Hans for all your hard work on this radio, it's truly amazing! John
Started by John R @ · Most recent @
QMX+ front panel pcb too wide 3
Just finished assembling a QMX plus. Went to put in a case and it doesnt fit. The front panel PCB is wider that what is pictured in the manual. It appears that it didn't get trimmed properly by the manufacturer. This is the picture from the manual, the yellow boxes represent the extra parts my PCB have. what would be the best way to trim these pieces off without damaging anything?
Started by N0GRP - Rob Sullivan @ · Most recent @
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