Re: What about 13.6 volts?
Alan,?
Lower voltage in and lower power out both make lower heat. I see no problem in lowering risk to rig!?
I used 7809 bolted to case internally to keep voltage exactly right. It does run warm at 13.8 supply, but not excessively s; i.e., I don't burn my hand when I touch it. I could bolt an external heatsink on top, but I don't think it's necessary.?
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73, Dan? NM3A
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Hans, Are the frequency limits ignored during the filter sweeps? ?That is, can the start frequency be less than frequency min, or the maximum of the frequency sweep be greater than frequency max as set in the band configuration?
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On Aug 6, 2022, at 11:00 AM, W8NUE <w8nue@...> wrote:
? Hans, Thanks for keeping us posted on updates/changes.
I do have a question regarding the band configuration: since it shows a selectable Start Frequency and Step Frequency I conclude that I need to know the Default Number of Steps to be able to control the Sweep Width. ?Is this correct? ?Is that number about 50?
Have I missed something? On Aug 6, 2022, at 9:46 AM, Mont Pierce KM6WT <de.km6wt@...> wrote:
?On Sat, Aug 6, 2022 at 05:56 AM, Hans Summers wrote:
The vertical marker showing the band center went missing in version 1_04.
I noticed that for 20m the Band Sweep setting was different than 80/60/40 so I just changed 20m sweep step from 100000 to 50000 (like 40m), and the center frequency appeared. Nice to know you're on top of it though.? I'll update to 1_05 when it's released. Each firmware release always seems to have some goodies?? hi hi Thanks, Mont
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
knobs: if you have or make the right standoffs, you can use the supplied M2.5 screws and standard knobs. Conversely if you have longer screws you can make the supplied knobs work.
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Re: What about 13.6 volts?
On 09/08/2022 13:47, Daniel Walter via groups.io wrote: My suspicion is that '12'V is nominal and 13.8V is really what's expected. Dan, Hans has said he runs his at 13.8 volts as a test rig, no failures. But he recommends 12 volts to be safer. As Evan says excess voltage is dissipated as heat so that makes most feel more comfortable. 73 Alan G4ZFQ
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Re: What about 13.6 volts?
The QDX manual states;
If you wish to use a supply of 12 - 13 V the 3:2 winding style is more suitable and will produce 4 ¨C 5 W output for 12 ¨C 13 V supply.?
I started with the 9v build and it gave me 5watts out. But I have 12v batteries I wanted to run it from so rewound for the 12v build. Now I only get 3.5W out at 12v. The manual warns against running too much output power (6W max), so I would think that is the criteria for max volts. However, I agree however, things are going to run a lot hotter at the higher voltage. Best to externally dump some of the voltage and heat as suggested.
73 Ken g4apb?
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Re: What about 13.6 volts?
Hi Hans,
I will not run my 12volt QDX on anything over 12volts.? The output MOSFETs are not the only thing that will generate heat in the enclosure.? The LM78m05 will also need to dissipate another 1.5watts, and the bias resistors for the diode switching circuits will also need to dissipate more power.? All add up to more heat.
I use one of my shack 13.5+volt power supplies with a DROK buck/boost DC to DC converter.? The cover is over 90% efficient.? The voltage can be adjusted, metering and current limits included.? There are less expensive models than the one I purchased:
73
Evan
AC9TU
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Re: What about 13.6 volts?
Check the manual for your power supplies.? Many of them can be adjusted via a small trimmer on the main board.
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Re: What about 13.6 volts?
I built mine for 9V, since Hans suggested that was preferred.?
However, if you look at the power curves Hans supplied, it looks like power outputs at 9V (9V build) and 13.8V ('12'V build) are about the same level. My suspicion is that '12'V is nominal and 13.8V is really what's expected.?
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73, Dan? NM3A
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Re: ATU-100 automatic antenna tuner
Are you talking about these links?
Steve Fabricant posted these in a previous post.
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https://www.youtube.com/watch?v=JceLhTV28oI
https://digitalshack.org/qrp-1-30mhz-antenna-tuner/
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Re: What about 13.6 volts?
Hi Hans,
I¡¯m using a 13.8v supply and 3x 1N4001 diodes in series worked for me to drop the voltage. They get warm but not excessively so¡
Before using the diodes the QDX case did get quite warm when left in receive mode, but now I can barely feel any heat from the case.
regards,
Jim
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
How tough would it have been for them to simply send some sort of knob that actually worked?
Well knobs for polyvaricons are not common. Usually you use a long enough (and not too long) M2.5 machine screw and a small nylon PCB standoff. Screw through the centre of the standoff into the threaded hole and that makes what looks very much like a normal
control shaft onto which you can fasten a normal knob with its grub screw.? The GQRP group provide these for their kits using polyvaricons so I'm surprised to find a Chinese supplier not doing what they normally do and just copying someone else's ideas.
Andy
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
IIRC there were several mistakes in the diagrams and instructions. ?For me the biggest issue is that the knobs simply do not work with the polyvaricons...... ? and, I'm a handy guy, and experienced fixer and make-do guy. ?How tough would it have been for them to simply send some sort of knob that actually worked? ?so, my copy of this sits in the parts box, and some day I'll need the vari-caps or antenna jacks.....for some other project. ?
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Re: Adding CW support for QDX?
Hi Hans! I hope all is well with QRPLabs!
I just had a nutty idea I thought I'd share with you. Please ignore this if you think it's silly or a waste of time or if you've already thought of it...
The B+ Voltage used for diode switching in the QDX should be proportional to the peak RF voltage at the output stage. Perhaps adding a divider and monitoring it (if you can find another analog input) can provide some kind of early warning about dangerous VSWR or other final amplifier problems?
Just one more thing you might want to add to list of things to "mull over"
stay well...
Mario AE0GL
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Re: Any builders out there for a QDX?
Another note of encouragement.
If you take it slow, and like Hans' says triple check each connection, you can't go wrong.
Like travel, half the fun is getting there.
Good Luck!
--Al
WD4AH
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Hi,?
My QDX is nearly finished, and I now realize that all powersupplies I own give out 13.6 volts. That's a whopping 1.6 volts more than advised. I did provide for extra cooling of the BS170s, and I made sure to have the 3:2 ratio on the transformer.
Will 13.6 volts still be too much??
Thanks,?
73 Hans PA3CRZ?
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Re: Any builders out there for a QDX?
Besides, just following directions (when building a new kit) isn¡¯t really teaching you anything. ?If it doesn¡¯t work and with help from others on this connection you finally figure out what is wrong, YOU LEARNED SOMETHING. ?Isn¡¯t this what a hobby is all about. Learning something new? ?How boring if you get a box, plug it in, and it works. ?What did you learn? How to plug in a new toy? Half of ham radio is learning about the how and why the boxes on your desk actually work. ?The other half might be the camaraderie of ham radio friends. ?Oh, yes¡. There are those who get a charge out of making contacts with other hams. Even more fun. ?I am 77 and still learning, sometimes by my mistakes in making the build. ?But learning from a mistake will never be forgotten. ?Experience has its price but it is worth every error, at least in my book.
Dave K8WPE since 1960 David J. Wilcox¡¯s iPad
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On Aug 9, 2022, at 6:28 AM, John, KB2HSH <john.marranca@...> wrote:
?OK, here comes some truth: if I can do it, anyone can. Due to the rigors of my career path, I have carpal tunnel issues along with arthritis in both hands...let's just say that my soldering skills have seriously deteriorated since the radios that I built in college.?
What helped me:
-magnified Ott light?
-10x jeweler's loupe (thanks for the tip, Hans)
-micro-tipped soldering iron?
-thin solder
-PATIENCE
Mine worked upon first fire up...and the ONLY reason that I blew mine up was 100% my fault.?
You got this!
John KB2HSH?
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Re: Any builders out there for a QDX?
OK, here comes some truth: if I can do it, anyone can. Due to the rigors of my career path, I have carpal tunnel issues along with arthritis in both hands...let's just say that my soldering skills have seriously deteriorated since the radios that I built in college.?
What helped me:
-magnified Ott light?
-10x jeweler's loupe (thanks for the tip, Hans)
-micro-tipped soldering iron?
-thin solder
-PATIENCE
Mine worked upon first fire up...and the ONLY reason that I blew mine up was 100% my fault.?
You got this!
John KB2HSH?
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Re: Hakko 20% off sale, August 9th
Thanks for the tip,. Just ordered the FR301 I always wanted. They are expensive but absolutely great for desoldering. Which as I get older it seems I have to do more of¡.. grin. Also picked up their small fume extractor. After 60 plus years of sniffing the lead smoke, I guess it¡¯s never to late to be safe¡.
jim
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
Thumbs up! Gonna get me some of that. (I was pleasantly surprised when my KD1JV Tribander kit came with the slippery decals. ) JS6TMW
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
And do remember not to follow the instructions when installing the inductor in this tuner. That¡¯s the key to success as it took me years to learn,? -- Sverre
LA3ZA
http://la3za.blogspot.com
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N3MNT
Keith "Al" AG5GW
David Wilcox K8WPE
Jim