Hi Roelof,
Interesting result with 2x3 BS170s. What is your 2x2 output?
Something I have been thinking to try is stacking a second ACT08 on top of the existing one. My simulations seem to show that gate drive is very important.
Is your build a 12 volt or 9 volt build?
Tony
AD0VC
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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:
...
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
|
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
|
Re: QMX+ front panel pcb too wide
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Re: QMX+ front panel pcb too wide
They should be scored already and just bend off easily using needle nose pliers.
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QMX+ front panel pcb too wide
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?
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Re: Record number of assembled transceivers shipped in March
Congratulations Hans. ?You’re doing a fantastic job and I’ve enjoyed every experience I’ve had with your wonderful product and business!
?
73 de Brent VA3YG
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Re: SWR and PWR does not show lcd
On Tue, Apr 8, 2025 at 09:41 AM, <ec7zv0@...> wrote:
this is ?
Yes. Was display power and SWR also switched on? The plan was to check if there is a connection between these values.
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Indeed! ?I would also like to add my thanks to Jeff Moore, W1NC - he is the guy to go to. ?Like you, I had a problem (several really) with my QMX build. ?Jeff did a great job with the repair, kept me informed, and provided a detailed list of what was done. ?
This forum and Jeff are extremely helpful.
?
Dave, AD8LM
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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
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QRP Labs kit shipping update
Hi all
During my absence on family vacation last week there was a major storm last Thursday, a lot of rain and thunder and lightning. After one close-by strike my colleagues?reported crackling and sparking on cables in our office, and since then we have?been without internet... the ISP say the modem is working fine (they test it from their end) but we tell them it isn't actually delivering us any internet.?
Anyway regardless of that, today I woke up and figured out how to USB tether my cellphone to the PC and share the internet to the PC. And got my shipping colleague doing the same thing via her iPhone. So 2 of our 6 QRP Labs office computers (which are the most critical two) are back online while we wait for someone from the ISP to visit. We are now working?on catching up on the shipments from last Thursday to today.?
Meanwhile after all the crackling and sparking my colleagues thoughtfully?unplugged my antenna. Full marks for effort... but the damage was evidently already done by that time: when I returned from vacation and switched on my QMX+ the thing popped and current went to several amps... I replaced the four BS170 PA transistors (one of which was visibly cracked); still not getting correct power output and performance I realized I need to replace the Q508 Tx/Rx transistor which had also apparently taken a hit. After all that, happy to say everything is back in order, the radio is working properly once again!
Meanwhile: we ran out of dummy load kits, and the 1.000 new PCB's are on the way via FedEx. They are going through customs processing in Izmir today and after that the imports normally reach me about 2-3 days later by road via the domestic courier who are the local FedEx agent. So some of you who ordered a Dummy load kit might be wondering why your order didn't ship yet, this is the explanation, please wait a few days.
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Record number of assembled transceivers shipped in March
Hi all
I have updated the assembled kits page?
In March 2025 we shipped 280 assembled transceiver orders (some containing more than one transceiver). This is a record high number. The waiting time for assembled transceiver orders is currently around 1 month.?
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On Mon, Apr 7, 2025 at 08:28 PM, james jones wrote:
I’m going to touch up all 16 of the display header pins. What a bad place for a soon to be 83 year old duffer to be soldering. Why couldn’t that bave been added to the display board before mounting?
It can be, assemble the front PCB, 16 pin connector and display using bolts and nuts between the display and the front PCB.? Solder the 16 pin connector pins to the display only.? This does the inaccessible contacts without the front panel in the way.? Disassemble and reassemble with the front panel, spacers, display, nuts and front PCB.
?
You can also disassemble it when it's all assembled, remove the rear nuts then unscrew the screws, taking care that the various spacers and nuts aren't turning.? Just take your time.? I know because I also missed a soldering one of the pins.
?
Chris.
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Re: SWR and PWR does not show lcd
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hi, may i`m wrong with some 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 , but going back to a non ssb fw doesn`t help.
any suggestions ?
?
vy 72/73 de Udo DF4BJ /qrp
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Re: SWR and PWR does not show lcd
For test switch please display voltage ON.
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Re: SWR and PWR does not show lcd
I've tried your recommendations several times, and it doesn't work.
I've attached photos of the problem.
1. PWR/SWR Display ON
2. Hardware Test - My external meter indicates 2 watts and the same SWR.
3. Transmission test in WSPR mode. My external meter indicates 6 watts and? SWR 1.2.
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Re: GPS module GY-GPSV3-NEO wont change baud!
On 07/04/2025 18:25, Michael Pupeza via groups.io wrote: HELP! I need to change my QRP Labs GY-GPSV3-NEO module, which has the UBlox NEO-7M-000 chip on it to 4800 baud, Mike, I do not know what module you are referring to. I have just checked with a uBlox M7 and find I cannot get uCenter to permanently change the baud rate. After a cold start it goes to 9600. I seem to remember I found that before... It does save NMEA sentence configuration. In the past I have used a backup battery which will save configurations. Perhaps there is a uBlox group somewhere? Might give some clue. Although others seem to have the problem Maybe some things are stored on-chip, others in flash. 73 Alan G4ZFQ the old NMEA 0183 standard for the TinyTraker3 APRS units. I can use the UBlox u-center25.03 and everything I receive and send from it appears to work, telling me that the RS232/TTL interfaces that I try are correct. However, going into Messages View - UBX - CFG - PRT - TragetUART1 (or any other) setting BAUDRATE to 4800 and hitting the Send button makes NO CHANGE (EVER). It stays at 9600 Baud!
Is there another way to try this and make the change permanent? Perhaps there is an inhibit connection on the chip? Or some sort of authorization command? Connecting a terminal program gives me the continuous GPS strings so the module is correctly putting out my location etc., so that part is also working fine (at 9600).
I appear to be stumped! Miniature GPS units running at 4800 Baud are pretty rare and I want to resurrect my Altoids Box Pocket Tracker with one to make it truly pocket size, again.
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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
?
 
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Re: QMX+ no power output, low SMPS bias current
On Tue, Apr 8, 2025 at 06:51 AM, Stan Dye wrote:
- when you measured the output, did you have a dummy load attached?? hopefully so, unless your scope has a 50-ohm termination option turned on (but most inexpensive scopes don't have an internal 50-ohm termination).
- when you measure, are you measuring ms would be 100mW).?? So please first confirm your measurements.
?
Please do not measure the output of a QMX using the internal terminator of an oscilloscope, you have a good chance of magic smoke coming out of the oscilloscope.
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N0GRP - Rob Sullivan
Udo Die?elberg DF4BJ
