Sorry for the delay. Life got busy .
And I actually haven't tried the fins yet.
I did some test runs on my fan modified QMX HB and my fan modified QDX HB. I found that I could safely push 50% duty cycle WSPR cycles, at 4w and 5W outputs respectively, for over an hour on both if I elevated the units about 1 inch above my worktable. ( Sitting just a bit of the short edges on? two stacks of small Post-It notes. ) Saw worst cases of an extra 4-5 or so degrees of exhaust heat rise.
I also found that the exhaust air would return to the normal after idling in RX within about 4 to 6 minutes.? My fans are just small 25x25 mm units. Don't move a lot of air, but are super quiet, only use about 28ma, and do make a difference compared to being fully closed up and sitting flat on the worktable.?
If just in RX,? The QMX appears to run about 3 degrees C above the surrounding ambient air ( ambient being around 24 to 27 C) while the QDX runs about 2 degrees above. This is in the fan on configurations.?
I want to repeat those tests with an LM35 sensor attached with some tiny drops of super glue to the hold down washer for the PA xstrs with both fan on and fan off conditions. This may give a better indication of what's happening temperature wise closer to the little heat buggers.?
Then I may try the fins on the bottom of the case idea I originally envisioned. Especially with some JS8 scenarios.
Fun, fun, fun ....
GREG
On Sat, Feb 15, 2025 at 7:36 AM, Nate Reik via groups.io <natereik@...> wrote: Greg, curious to see what cooling fin blocks you're trying out.
?
-Nate
N8BTR
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Re: Waterfall / Panadapter on QMX+ : Add a freq-out for a second receiver?
There is a fundamental lack of understanding of the SDR receiver.
?
First there is essentially no IF, its direct to base band which is the
IQ outputs.? All the work is done in the digital realm by the
ST32M4xxx mpu.
?
For second receiver the bandwidth of that down conversion is
Relatively narrow band so the panoramic view (waterfall) would
be narrow as would the frequency of the "2nd" receiver.? Doing
a close in waterfall is taking what data there is (IQ outputs)
and translating that to a display format.
?
Generally the idea of upstream tap is limited to radios that
are multiple conversion superhet transceivers.? That is typical
of many radios like ft817, FT450, IC756 and a large number?
of others.?
?
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
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On Tue, Dec 17, 2024 at 05:43 AM, Karl wrote:
Why twist the wire in RWTST? What purpose does it serve?
It serves the purpose of working better than not twisting it.? ? We can spend all week speculating or debating or citing theories as to why but that's not the priority here?
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Dale-? The toroid parts listing in the latest manual for the Rev 2 board has not been corrected.? But, it is correct in the board Rev. 3 manual.
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Dave- LOL.? Yeah, it is actually kind of relaxing to wind these things. But the counting does stress my poor little brain....
Thanks for the encouragement.
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Re: MI QRP Weekly Zoom Chat
Ed,
I tried to check in three times but failed. I'll try again next week.
Jerry/k5sop
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Re: Waterfall / Panadapter on QMX+ : Add a freq-out for a second receiver?
On Fri, Feb 21, 2025 at 01:07 PM, Alan G4ZFQ wrote:
?
Thank you for your reply!?
?
That's what I thought, I'm assuming, there's no IF at all?
With very delicate work you might get IQ out independently but would need to be skilful and just end up with the same output as the QMX standard IQ out.
My current approach is not to get I/Q separately (although this might be a viable solution, too), but to 'tap' the analog RX signal (or IF, if available) and convert it to I/Q, using an independent SDR receiver. The I/Q mode as-is does not fit my requirements.
?
I don't have a block diagram for the QMX and the receiver schematics are not an open book to me. So my question is: Is there any point in the cirquit where I can 'tap' the analog RX signal (using a buffer board in order not to draw power from that signal)?
?
It's always possible to get the RX signal directly from the antenna input. That will work. However, I will have to cut that connection on TX in order not to fry my second receiver. The buffer board I intend to use, does have that ability. In that case I need a point on the circuit, where i can 'read' the RX/TX status. I will have to convert that signal to +12 V for the buffer board. Using CAT is not an option for this case, because it's to slow.
If you want a tap for the RX antenna it might be possible but to do that without affecting the QMX operation will need very careful consideration.
What you are asking has never been discussed here.
Great point to start a discussion! I would not have asked without studying the manual and searching this group first. Unfortunately I have not been able so far to get the necessary information - what, I admit, has to do with a lack of basic understanding of the inner workings of the QMX.
?
Let's summarize my requirement: I'd like to have a second independent SDR-Receiver while QMX is in RX. I am very used to that feature and I don't want to miss that when working with the QMX. I will share my experience (solution?) here, I thing that might be interesting for other users, too.
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Re: CW practice / Rag Chew
Ed, that’s super good of you. I will try to hop on. K2CWC, FN33, Chris. I wasn’t aware of reverse beacon. Super helpful. ?
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MY QRP Labs QMX-PLUS-NRV-CW/FT8/SSB? rig has shipped !
Just received the email from Hans' crew at QRP Labs and DHL Tracking tells me that my new rig is on its way !
Gonna have to clear some space on the operating desk ! This new rig shall be used in the New River Valley of Virginia.
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On 2/20/25 I had a CW practice / rag chew session on 40 meters. I worked three stations:? | Date / Time | Call | Bnd | Frequency | Mode | Power | Rec | Snt | Name | SPC# | Comments | | 2/20/2025 23:33 | N8NHT | 40 | 7.038 | CW | 40 | 579 | 449 | Hayes | TN | K3 at 40 watts 100 ft sloped doublet | | 2/20/2025 23:13 | W3APA | 40 | 7.038 | CW | 40 | 599 | 579 | Tony | PA | K3 at 40 watts 100 ft sloped doublet | | 2/20/2025 22:51 | NG4S | 40 | 7.038 | CW | 50 | 229 | 449 | Tom | SC | K3 at 50 watts 100 ft slopping doublet |
Conditions were noisy at the start but improved dramatically when it got dark. SSN = 119, SFI = 184, A = 7, K = 0.
I will be doing another CW on the air practice session?Monday 24?February. Anyone 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:
Time - 9:00 AM Eastern Time / 14:00 UTC
Band - 20 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
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I believe the 9v version of the QMX's T501 is a fairly straight transmission line transformer with a 1:1 turns ratio
using twisted wire for a transmission line.
?
The 12v version of T501 needs a 3:2 turns ratio which can't all be done as a transmission line transformer,
so that is supplemented by an additional single wire winding which acts more like a normal transformer.
Which is "really weird".
?
Still trying to fully understand it, this seems to be the best explanation I've found yet:
?
Jerry, KE7ER
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My newest QMX+ kit Rev 3 arrived and was assembled exactly one week after ordering!
The diagnostics test page showed output power (0W) and SWR (random values). Everything else was OK.
All sweep tests showed strange results. Yes, the dummy load was in place.
?
So I decided to power off and check all solder joints again.
?
The QMX was on the table without the enclosure and I did not get a good grip on it.
As I pressed the Vol button for power-off the QMX moved on the table and the
long button press was interrupted, giving *two* long presses like keying Morse M.
?
The display flashed abnormally showing some text and dimmed.
All happened so quickly that I did not see exactly what happened.
No smoke, no hot components.
?
Now I can not power-on as the radio does not react to any button press. Nothing happens.
If jumpered for forced firmware update, no flash drive appears on the PC.
?
This could be a firmware problem.?
Is it possible that the second long press of the Vol button started the power-on cycle while still powering off and writing data to the flash memory?
Clearly,?while performing power-off?and saving data into the flash memory,?the firmware should ignore the button press for power-on.
?
--
73 Matti OH6BEX
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Has the rev. 2 parts list been corrected?
On Fri, Feb 21, 2025, 4:50 AM David Wilcox K8WPE via <Djwilcox01= [email protected]> wrote: Larry,
Your toroids look wonderful!? After a few more you can do them in your sleep or while watching Jeopardy and Wheel with your wife.? I find winding toroids like what I used to see with my Grandmother and Aunts do when they would knit or crochet while talking ?or playing cards.? It becomes automatic after a while. And it’s fun too. Dave K8WPE
PS ?Now I understand…… He who dies with the most toys has probably forgotten much what he has and why……. So true!
? I'm in the process of assembling my QMX+ (board rev 2), and I'm about to begin winding the Low Pass Filter toroids (section 2.12, page 32).
?
When winding the previous toroids, I found it helpful to take a closeup photo of the completed toroid to re-count the # turns (as a double check before installing).
Since I already have those photos, I thought I'd run a couple of them by the group before I move ahead with the Low Pass Filters. How am I doing?
?
Here is my L405a ("small blue" w/ yellow on bottom- T37-17 core)....
<QMXp Toroid L405a _IMG_1967.JPG> ?
?
Here's my L405b ("small pink" T37-0 core)....
<QMXp Toroid L405b _IMG_1970.JPG> ?
Any suggestions or comments on my work before I wind the remaining toroids?? I'm wondering if I need to be more careful about keeping the gap between windings more consistent... does that matter? I'm not using the entire core; the "start" and "end" wires are positioned to line up with the PC board holes; does that look right?
?
Thanks again,
Larry
?
PS- Note that the board rev. 2 parts list (page 16) reverses the toroid types used for these two coils (it says L405a is pink and L405b is blue (yellow) ).? This error has been corrected in the board rev 3 assembly instructions.
?
?
?
?
-- Dale Hardin
KS4NS
Elberta, AL
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We had twelve folks join the MI QRP Zoom Chat on 20 February. Please join us Thursday February 27 (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 be loaded or installed. Anyone can join and non members are welcome. Details are here:
The topic for Thursday, 27 February will be Ed AB8DF leading a discussion on using a Raspberry Pi as a shack computer.
Pete WK8S Ed AB8DF Ernie W3ETE Tony W8CDC Stan WB8QJZ Casey KC9IH Larry AC8YE Dave N8SBE John M7FZC Stuart M0SGV Yvon AE7YD Jerry KI4IO
Stuart M0SGV lead a discussion of a prisoner of war radio. It is in a military canteen. He had some slides. To hide it they hung it in the latrines and on beds. Stuart saw a presentation at FDIM back in the day. Bought the valve / tube at that very Hamvention. Getting the canteen and various parts was part of the build challenge. He looked on eBay for a canteen with out much luck. Then at a swap meet in San Diego he found one for $15.00. It was not aluminum. It was stainless steel and stamped 1945 not 1942/1943. He did not have any bamboo to wind the coils. He would like to see an original but not sure if any exists. Cloth covered wire is still available for vintage car restoration sites. Had a video of the radio in operation. The powered it with a home brew power supply using back to back transformers to get the HV. Where did they get the high impedance phone and other parts at a prisoner of war camp?
?
Jerry is new to the chat. He is an avid QRPer. He has lots of home brew qrp rigs. Jerry is in VA.
Pete needs some cloth covered wire and wants to know from Tony where he can get it. Pete is restoring an old regenerative receiver.
Jerry’s dad made a Knight Space Spanner radio back in the day.
Ernie put an antenna together for his KH1 from what K6ARK talked about at FDIM last year. It is a Rybakov antenna with a fishing pole. Just too cold to play with it outside.
Pete had a Chameleon antenna which came with the wrong parts. He ordered it from DX Engineering. Chameleon Antenna replaced the parts and he was very impressed with their service and support.
Next weeks topic: Ed will lead a discussion asking the question: Should I move to a Raspberry Pi as my shack computer?
The agenda for the February 27 QRP Chat:
- Pete to do a short introduction and acknowledge any new folks to the Zoom chat.
- Ed will lead a discussion asking the question; Should I move to a Raspberry Pi as my shack computer?
- After the discussion on the Raspberry Pi has completed, there 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
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Re: Waterfall / Panadapter on QMX+ : Add a freq-out for a second receiver?
On 21/02/2025 10:49, 410733 via groups.io wrote:
If you want a tap for the RX antenna it might be possible but to do that without affecting the QMX operation will need very careful consideration.
What you are asking has never been discussed here.
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Re: Waterfall / Panadapter on QMX+ : Add a freq-out for a second receiver?
On 21/02/2025 10:49, 410733 via groups.io wrote: I'd really like to know if I'm on the right track - and I'm lost in looking for a good point on the board to tap the frequency Joe I'm not sure what you want to do but IF tap is not possible. The QMX does not follow normal receiver practices. With very delicate work you might get IQ out independently but would need to be skilful and just end up with the same output as the QMX standard IQ out. Study the manual, get it working, understand how it works, think modification later. 73 Alan G4ZFQ
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? Rich,?
Don’t despair. ?Get some low temp ChipQuick and read/watch re the use of that interesting product. ?Beware there are a few different ChipQuick products, each for different kinds of repairs. ChipQuick keeps the solder on all the pins liquid long enough to remove the chip. ?Then clean up the board with solder braid and alcohol to remove the rosin residue. ?Then with the new chip (after you have looked for and found the error) solder two pins down, one on each end. ?Then flood all the pins with solder and then use the solder wick again to remove the excess solder. ?ChipQuick works well for this last step too. ?You may not be able to get a working board in the end but what you learn doing those steps will prepare you for future repairs.?
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Bruce Akhurst
Bill, N4QA/QRP
Dale Hardin KS4NS
David Wilcox K8WPE