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Re: No uploads - support replied
Hi all I am technically the owner of this group. But Farhan is the real boss. So I leave it up to him, what to do. One thing nobody has mentioned yet, but may be worth investigating. A feature that has which wasn't available in Yahoo is what calls "integrations" where other services can be integrated with the group. One mentioned is DropBox (for files storage). This could provide a storage solution that doesn't cost anything. I found this in a help page: Member integrations allow your members to export content automatically from the group. One example of this is the Dropbox integration. With it, your members can have attachments that are sent to the group be automatically saved to their Dropbox account. There are options to specify the type(s) of attachments to save, and whether the messages should be tagged with a specific hashtag. Member?integrations are accessed in the Subscription area of the Group. 73 Hans G0UPL |
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Re: bitx40 newbie build, if touched IRF510 switches and locks to transmit, takes 3A
Well, Andrew, Jerry pretty well covered everything of merit to note.
How will you know if you have damaged the IRFxxx? It won't work, period. These devices are go/no-go things. They either work or they don't because of the almost instantaneous over-heating and destruction of the die area. As noted, it is very small in relation to the overall size of the device. A good heat sink is absolutely necessary as there is such poor heat transfer through the case. Even then, as noted, if the sink is warm to the touch, the die is too warm and due to fail. Using the chassis as a heat sink, with proper RF isolation is a good practice. Yes it does introduce some capacitance, but usually not enough to matter. The most common real path for oscillation is through the internal diodes to the source. There is a capactive connection to the gate which completes the feedback circuit. What you experienced is probably a device close to oscillation, where a small additional capacitance on the drain triggered the feedback circuit. Based on some of the past cures, it is likely that supplying 400-500 pf, to ground from the drain would have cured it! Every device and its characteristics is different. I read in another message where someone got 7W out with only 750 ma of current. Yes, that's possible...but the signal was probably very dirty as well. What is different about the power MOSFETS is the gate area. It is not one connection; it is several (maybe 6 or 8) connections is parallel. That is why it has such a high input capacitance. It works well for power switching and Class D amplifiers, but very poorly for Class B and Class C analog amplifiers. There is one very small linear area which can be exploited. Exceeding it can and will cause near instantaneous destruction. Finding and taming that small linear area is the goal of all the amp builders. There is at least one German (or French) design which uses 8 devices as 4 push-pull pairs to achieve several hundred watts out. It can be done. Remember, doubling the drain voltage gives about 4 times the output power with about the same input. That's a pretty good return on effort. As with all linear amps, layout and impedance matching are critical to success. It is a usual practice on higher level amps to provide an external zener diode to limit AC excursion. Typically is is about 36v but it could be anything that does not conduct in normal operation. The fact that your device was "working" made me suspect oscillation rather than failure. All amplifiers are prone to becoming oscillators; these devices do it a whole lot easier than most, that's all. This (and the small linear region) was noted by Doug Demaw and others when amateurs first began investigating their use back in the 1970's. Various means were devised to counter the random oscillation. The most effective means, as Allison notes, is to install a 10 ohm resistor at the gate in the input lead (not to ground). This suppresses the oscillation; it does not remove the original cause (n.b.). There is a lot more you will find out along the way. Linear amps of all kinds are very fascinating RF devices. Hang in there. (Wait until you run into thermal runaway, Hi). john AD5YE |
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Re: Project box
Buck
Was it cheaper/better on Amazon? How is the size?
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Buck, k4ia Honor Roll 8BDXCC On 2/27/2017 9:11 PM, Dennis Zabawa wrote:
I have one of those, bought through Amazon, that I am working with. I |
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Re: Project box
I have one of those, bought through Amazon, that I am working with. ?I had custom front and back panels made by . ?They have a free, downloadable design program that is easy to use and their prices and delivery are great. ?I will post pix of the completed unit at a later time. Dennis KG4RUL |
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Re: bitx40 newbie build, if touched IRF510 switches and locks to transmit, takes 3A
1/4 watt should be fine. If you blow the IRF510, it won't draw any current from that 12v PA supply. ?Or maybe it will short, and draw everything your powersupply can give it. Proper name for suspected problem here: ?parasitic oscillation ? ?So that IRF510 is operating as an oscillator at some random frequency instead of as an amp. ?Probably at a very high frequency. On Mon, Feb 27, 2017 at 03:34 pm, Andrew Kasurak wrote:
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Re: Bitx 40 frequency limitations.
Steve Black
¿ªÔÆÌåÓýNo need mod your radio. I can be heard on 40 meter SSB from time to time! Steve kb1CHU Sent from my Smart Phone I said I'd never get. -------- Original message -------- From: Dr Fred Hambrecht <AAR4MI@...> Date: 2/27/17 5:49 PM (GMT-05:00) To: [email protected] Subject: Re: [BITX20] Bitx 40 frequency limitations. I extended mine to receive CHU on 7850. ? v/r Fred W4JLE ? ? From: [email protected] [mailto:[email protected]] On Behalf Of John Smith via Groups.Io ? I saw in the code that the frequency upper and lower limit is preset in software. I am sure it could be set for your band permissions if someone wanted to. But how far out can it receive with it's hardware limitations? I would like to receive 10 Mhz for WWV clock for frequency calibration. |
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Re: bitx40 newbie build, if touched IRF510 switches and locks to transmit, takes 3A
Ok. I put in the 1k gate-gnd, and that actually did stop the majority of pseudotransmit (is there a proper name for this?). A longer (1 min?) transmit test with a two tone gen I built did cause it to switch over again, so an improved heatsink is certainly part of the plan. I'll give a go at the 10 ohms in series with the gate. Is 1/4W ok? K1-1 is 0v when in normal receive mode. How do I know when I've damaged the IRF510? Obviously smoke out, but are there less obvious failures I should note? Thanks, Andrew (VA2WCH) |
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Re: Bitx 40 frequency limitations.
¿ªÔÆÌåÓýI extended mine to receive CHU on 7850. ? v/r Fred W4JLE ? ? From: [email protected] [mailto:[email protected]] On Behalf Of John Smith via Groups.Io ? I saw in the code that the frequency upper and lower limit is preset in software. I am sure it could be set for your band permissions if someone wanted to. But how far out can it receive with it's hardware limitations? I would like to receive 10 Mhz for WWV clock for frequency calibration. |
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Re: Basic Arduino Programming Knowledge
ARRL Sells a nice book for $35??Arduino for Ham Radio by Glen Popiel, KW5GP ? The book is full of neat ham radio Arduino projects. ?You can also just download the code for the projects at??and not pay the $35 - but IMHO there is so much backgound materiel in the book it is wroth the price |
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Re: Basic Arduino Programming Knowledge
* For the search function:
Good books have something similar, that is, Table of Contents and Index. * Books are readable after your Kindle is long recycled or got an update or your book license was revoked or your account deleted or.... I vote for the book ;-) Kindle is cheaper and has the advantage that I have it on the screen of73 de Patrick OE6PSE -- Engineers motto: cheap, good, fast - choose any two Amateur Radio Operator / Ham / Funkamateur / QTH: JN77rb One of the lucky 10.000: Use Mail Encryption Today! PGP Key ID: 0xDF8A127E5A120903 Patrick Strasser-Mikhail OE6PSE <oe6pse at oevsv dot at> 73 de Patrick OE6PSE -- Engineers motto: cheap, good, fast - choose any two Amateur Radio Operator / Ham / Funkamateur / QTH: JN77rb One of the lucky 10.000: Use Mail Encryption Today! PGP Key ID: 0xDF8A127E5A120903 Patrick Strasser-Mikhail OE6PSE <oe6pse at wirklich dot priv dot at> |
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Re: Basic Arduino Programming Knowledge
¿ªÔÆÌåÓýWell, ? I have the first edition as epub which I can read in my Sony reader, on my laptop and on the desktop and I have the second in the printed edition. I prefer the paper edition clearly above the digital one. Because it is not a novel where one starts to read on page 1 on the left top of the page and continues until the last page at the right bottom. Instead I browse through the book and read a chapter here and there just to answer a question I have or to delve in a subject that interests me especially at that moment. But everyone has his own style of reading and learning. But I also like to be away from the screen now and then and still enjoy my hobby. But in whatever form you will buy it and against what price, it is worth every eurocent! And don¡¯t wait too long! ? 73, Cor ¨C PA4Q ? ? Cor, thanks for your reply. I found it on Amazon.de for €36.33 as paperback and for €25.32 as kindle edition. I think I will order it, but I am not sure, which version I should take. Kindle is cheaper and has the advantage that I have it on the screen of my PC or my tablet with the posibility of text search. Paperback on the other hand does not need a wire to the power socket or a battery ;-) Will sleep over it. ? |
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Re: Getting stuck
Jack Purdum
The error message is saying you are compiling a file named raduino_new_library.ino, but the file that is attached is a different file and it compiles without error. Did you send the wrong file? Jack, W8TEE From: Helmut OE4HDS <hs@...> To: [email protected] Sent: Monday, February 27, 2017 1:29 PM Subject: Re: [BITX20] Getting stuck Hello Jack, may I ask you for a code validation? I wanted to allow me to increase the tuning speed by pressing the button connected to A3. So I made a modification to the doTuning function. Seems to work, but I am not sure, if this has some flaws the way I did it. Could you please take a look at it and tell me what you think? As you know, I am not yet familiar with coding Arduino sketches. I attached my test sketch. Hope attaching workes. BTW, there are warnings for every printLine1 and printLine2 E:\bitx40\raduino_new_library\raduino_new_library.ino:666:34: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings] ? ? ?printLine1("Raduino v1.01"); I fugured out, that there must be some reason why it does not want a string as paramater for the function. So I changed all this calls for example from printLine1("Raduino v1.01"); to ? strcpy(c, "Raduino v1.01"); ? printLine1(c); Now all warnings are gone and it still seems to work. Do I have to do it again, after I download the next version of the official sketch or could someone "repair" the original sketch? Helmut, OE4HDS |
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Re: bitx40 newbie build, if touched IRF510 switches and locks to transmit, takes 3A
For our one IRF510, a good size for our heatsink is half of the 24 sq inches that Allison uses for two devices, and with 1 inch fins. Lots of good heat sink material in old PC motherboards and power supplies. ?I found a motherboard chipset heatsink that looks ideal, will trim it to size using my $10 Harbor Freight angle grinder with a cut-off wheel. ?For use at 12v most people seem to be getting by fine with the stock heatsink, but it is marginal. On Mon, Feb 27, 2017 at 12:25 pm, Jerry Gaffke wrote:
So figure 4x3=12 sq inches and 1 inch fins ? |
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Re: bitx40 newbie build, if touched IRF510 switches and locks to transmit, takes 3A
I mentioned heat a couple times in my last post. ?That is not your primary problem, the IRF510 is not hot when it first goes into oscillation. Allison's post is worth going over thoroughly if you want to know about using IRF510's at RF. ??/g/BITX20/message/22597? She knows what she is talking about. ?She says that if the heat sink is at 50C (122F) ?then the die is much hotter, and close to failure. ?These parts have a very small active region on the die and poor heat transfer characteristics. ?So a heat sink that is more than comfortably warm is too hot. ?She says her 2 IRF510 amp has a heatsink that's 4x6 inches with fins that are an inch tall. ?So figure 4x3=12 sq inches and 1 inch fins. ?Ours is about 1 sq inch and 1/4" fins. ?I won't be using the stock heat sink with power supplies beyond 12v. ?Don Cantrell's blog post about heat sinking directly to a chassis wall might be a good way to go, but there must be insulation between the two as the IRF510 tab is hot with 12v and all the 7mhz RF destined for the antenna. Allison's recommendation for large heat sinks conflicts with John Backo's warning to watch out for capacitive coupling from the drain pin and ground. ?(Note that there is a drain pin, plus the tab that connects to the heat sink is also connected to the drain.) ?Allison doesn't mention that, but does mention short traces. ?The Bitx40 board is not optimal in that regard but should be fine, and does have the very short connection from IRF510 source pin to ground that she singles out. |
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Re: bitx40 newbie build, if touched IRF510 switches and locks to transmit, takes 3A
51.2 ohms is great. ?Anything between 25 and 100 ohms is ok when running the final from 12v. ?Not an issue if you are only attempting to receive, I doubt any VHF oscillation would get through the 40m lowpass filter between the IRF510 and the dummy load. And it does indeed sound like John Backo's oscillation. ?Gate should be close to 0 volts whenever in receive mode. ?Suggested suggested the cause was capacitive coupling from the IRF510 drain (the tab that is attached to the heatsink) to ground that is causing this. ?If you can you might try keeping any other objects (such as a metal chassis) away from that heatsink till this problem is solved. > ?Pin 1 of relay k1 goes to 0.9v at pseudotransmit. Yes, should be low unless transmitting with PTT pressed. ?What voltage is at K1-1 when just receiving without this pseudotransmit problem?
> Pseudotransmit happens more frequently once it's been triggered once Likely a heat issue, which can significantly change the IRF510 characteristics > I did grab a couple more irf510's, I've heard this usage is a bit hard on them. Allison's recent post suggested that with proper care they are quite suitable. ?But getting hot is killer. > As I follow it, the suppressor resistor you are suggesting is from gate (pin 1 of IRF510) to ground? No. ?Lift the gate pin (or cut that trace) and put a 10 ohm resistor in series with the gate. Could be that you just have an ?overly-sensitive/out-of-spec ?IRF510, and that swapping it out will fix this. ?But best to look hard for other causes first. Jerry, KE7ER On Mon, Feb 27, 2017 at 10:58 am, Andrew Kasurak wrote:
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Re: WIKI misdirection
Not fixed.
Someone changed all links to include "wiki/" in the front, so the bug works now the other way around. Patrick Strasser-Mikhail 2017-02-27 19:53: Seems this is already fixed. 73 de Patrick OE6PSE -- Engineers motto: cheap, good, fast - choose any two Amateur Radio Operator / Ham / Funkamateur / QTH: JN77rb One of the lucky 10.000: Use Mail Encryption Today! PGP Key ID: 0xDF8A127E5A120903 Patrick Strasser-Mikhail OE6PSE <oe6pse at wirklich dot priv at> |
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Re: Basic Arduino Programming Knowledge
Cor, thanks for your reply. I found it on Amazon.de for €36.33 as paperback and for €25.32 as kindle edition. I think I will order it, but I am not sure, which version I should take. Kindle is cheaper and has the advantage that I have it on the screen of my PC or my tablet with the posibility of text search. Paperback on the other hand does not need a wire to the power socket or a battery ;-) Will sleep over it. |
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Re: Schematic and other Raduino resources?
Thanks, Jack - this is a help. The Raduino seems like a great device, and I think plenty of Ham projects could be built around it.? r.rking41, I have all of the Arduino stuff I need. Raduino is what I want to build on.? It seem strange there are not more projects based on it. First will be an antenna analyzer, I think.
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Tom Clifton