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Re: On the subject of fake IRF510
Rich got it right.
These devices were originally intended for low frequency switching; they can handle large currents, but only for a very short time. Their use at RF DEPENDS on finding a very small gate voltage area which allows linear operation. Sometimes that area does not exist, even on the originals and true copies. Some later ones were especially designed for use at RF. They are not MOSFET switching transistors. So using a IRF MOSFET is always a case of possible pig in a poke. Some of them will not work no matter what one does to them. Fortunately, most will work, but tuning the gate voltage is absolutely critical. At around 5v, there is a sudden release of ALL available current at the drain to the source. This is the so-called "avalanche" condition. It must be avoided at all times if using the device for RF (which means that it is harder to use them when a full-time carrier is involved -- but it van be done). The other major consideration is the heat generated. These MOSFETS have very poor heat transfer characteristics. And there is a very small die area where the "switching' work is done. Heat transfer must be maximized and strictly controlled. Else, poof! There it goes (in milliseconds). It also very easily breaks into oscillation, especially VHF oscillation. That is controlled by impedance matching of the drain to the output. The best tuning is to set the gate voltage low (2v?) without a drain connection. Then connect the drain supply. Then slowly increase the gate voltage until a SMALL current increase is seen in the drain. That is getting as close to the linear region as one is able to do with these devices. This is true (and a characteristic) of all switching MOSFETS. (The major differences are in the peak voltage, the current each can handle, and the gate capacitances; these vary tremendously according to their die arrangement). Then connect and adjust your RF source to the drive transistor...this is also just about the recommended procedure for the BITX40. These devices work much better at voltages higher than 12v. Those especially designed for RF use (like the RDHHFxx) devices ARE designed to be used at 12v. Not true for switching MOSFETS. The RF devices are also much more expensive, but they are more or less guaranteed to work at HF. There are a few, like the 2N3555, which were in use very early. They are sort of bastard devices with sometimes good and sometimes bad characteristics. Note that the 2N3555 is really a MOS clone of the 2N3055, a NPN ordinary transistor. The 2N3055 gained fame as an output transistor in linear power supplies. This was designed as a MOS replacement, which in fact does run cooler than the original. Doug Demaw was an early investigator of these devices, and he noted very early on their "odd" characteristics. When the IRF devices first came out, it was discovered that they could be used as RF devices (much to the design engineers' surprise), but with all the caveats noted above. Incidentally, that Hackaday post is a copy of the one he put on his blog. It, and more, are available in full there. john AD5YE |
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Re: CQ tonight
it would be convenient if we had an echolink node just for real- time bitx contacts and troubleshooting.... On Jul 15, 2017 4:48 PM, <doghouse3@...> wrote: Unfortunately I get the single email with all the updates and it comes the next day. Would you be able to post a day ahead of time when you will be on. We just finished out BitX40 day before yesterday and would love to listen to you. Thanks, Joy |
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Re: W8TEE TFT/ VFO DISPLAY BOARD BOARD
Jack
I must have missed this in the build or setup. The voltage continues to change so it must be floating. I have the tft/vfo connected to the bitx40 power so don't think I have a ground problem. Could you resend the detail about the voltage divider? "If you connect the display voltage pin to your voltage source, it will flash one or two times at power up, but will only update itself if there is a measurable change in the supply voltage. My guess is that you don't have yours tied to either ground or a voltage divider. As a result, the pin is floating which is read as a new voltage which triggers a screen update.I had mine running several hours last night and it never varied enough to update the field".? art |
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Re: Mouse encoder?
Arv:
You are getting a little sophisticated here. The original mouse cutup was to keep only the ir circuit and discard the rest. Thus the signal was (and is) raw grey code. If the pc board is also included, then, yes, the communications protocol must be followed. I guess it is a simpler solution as the mouse can be used intact...however, the optical or laser mouse is a bit different. It is not so easy to recover the plain grey code generator. So using the protocol on them is probably a necessity. I presume the important thing is to distinguish which type of mouse one is working on. Once upon a time there was only one...now there are many. They vary. john AD5YE |
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Re: Still Not Working
Joe Puma
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On Jul 14, 2017, at 10:58 PM, Curt M. <Kc3hjp@...> wrote:
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Re: On the subject of fake IRF510
One thing to keep in mind is. IRF-510's are actually power MOSFETs, and NOT originally designed for RF amplification. Tolerances that might be acceptable for the original intended purpose, might not be sufficient for use as RF devices, so if you get MOSFETs that are at the extremes of the tolerance levels, they might blow when used as RF devices even though they may have worked just fine in power applications. So cut-rate IRF-510's might not be "counterfeits" per se, but they may have been near the edges of their tolerances (or even somewhat out of tolerance). Rich KC8MWG On Saturday, July 15, 2017, 3:05:40 PM EDT, Ken Hansen <ken@...> wrote: No, see comment below
The individual bought the parts on eBay, he didn't want to pay Mouser or Digikey shipping prices for such an inexpensive part: "Instead, [Ryan] found a supplier for five of these MOSFETs for $6 shipped. This was a good deal and a bad move because those new parts were fakes. Now we have an opportunity?" The fakes were 5 for $6 shipped. Ken, N2VIP |
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Re: Mouse encoder?
If attempting to use a PC Mouse as a rotary encoder and if you are doing your own software, you do not need to modify the mouse in any way.? A PC mouse emits character sequences as it moves.? All you have to do is to write a small bit of software to accept those character sequences and decode them as rotary encoder motions.? _._ On Sat, Jul 15, 2017 at 12:07 PM, Mike Yancey <mikeyancey@...> wrote:
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Re: Still Not Working
Jack Purdum
Nope...no solutions as I'm looking myself. However, I've been through the process you're going through and the good news is...you're doomed! You thought you didn't have enough time before, you've just opened a new, never-ending horizon of new projects. Enjoy!! Jack, W8TEE From: David Wilcox via Groups.Io <Djwilcox01@...> To: [email protected] Sent: Saturday, July 15, 2017 5:56 AM Subject: Re: [BITX20] Still Not Working OK Jack. ?I have avoided these little computers because at 72 I don't need another hobby. ? BUT since my Bitx arrived and after reading all the problems with it I just ordered your book. ?Darn, I am retired but have less time now than I had as an active family doctor....... Any solutions for that? ?? Dave K8WPE
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NEED A BIT OF HELP - TO FAULT FIND ARDUINO SKETCH ERROR FOR - USB FUNCTION
HI,
I am hoping someone can look at the info below and see where I might be causing the problem The serial monitor seems to indicate things are ok? When I select lsb is fine - good receiving When I select USB, the bitx vfo, ? display stays the same, but the bitx rx will switch to 3 khz above the original lsb freq but does not actually cause the bitx to switch the USB? I have been trying to figure this out for ?weeks but not quite there...Sure could use some help.... Serial took 0ms to start
-------------NOTE-----------------------
THE SI5351 CLK0 IS CONNECTED TO BITX40 VFO?
NO CONNECTION ON CLK2 OR CLK1
?
-----------------------------------------------
SERIAL TEST OUTPUT BELOW- Appears ok?
-----------------------------------------------
ID = 0x9341
100 Hz
sw:0
7100000 - DIAL
We've switched from USB to LSB ? --- DEFAULT STARTUP ?LSB
VCO : 489850000
bfo : ?1199850000
vfo : ? ?7100000
mult : 100
clk2 : 2
?
USB ? This is where i press the usb button
7099900 ?DIAL
We've switched from LSB to USB -------
VCO : 1910140000
bfo : ? ?1200150000
vfo : ? ? ?7099900
mult : 100
clk2 : 2
7100000
-------MY-- ARDUINO CODE----------------------------------------------
?
?if (bfo >= 1200150000ULL ) ? ? ?// TEST FOR USB
? ? {
? ? ? volatile uint32_t USB = 1200150000ULL;
? ? ? uint32_t vco = bfo + (vfo * SI5351_FREQ_MULT);// USB
? ? ? bfo = USB;
? ? ? tbfo = "USB";
? ? ?
? ? ? si5351.set_freq(( bfo + vfo) * 100ULL, ?SI5351_CLK2);//
? ? ? Serial.println("We've switched from LSB to USB");
? ? ? Serial.print("VCO : "); Serial.println(vco);
? ? }
? // ?else if (bfo < 1200150000ULL ) ?// MUST BE LSB THEN
?else?
? ? {
? ? ??
? ? ? volatile uint32_t LSB = 1199850000ULL;
? ? ? uint32_t vco = bfo - (vfo * SI5351_FREQ_MULT);// //LSB
? ? ? bfo = LSB;
? ? ? tbfo = "LSB";
? ? ??
? ? ? si5351.set_freq(( bfo - vfo) * 100ULL, SI5351_CLK2);//
? ? ? Serial.println("We've switched from USB to LSB");
? ? ? Serial.print("VCO : "); Serial.println(vco);
? ? }
?
ISSUE: -------------------------------------------------
When I switch to USB, THE BITX40 CHANGES where it receives up by 3khz LSB and is not actual upper sideband.
?
?
?
? ? ? //si5351.set_freq(( bfo - vfo) * 100ULL, SI5351_CLK2);//
? ? ? Serial.println("We've switched from USB to LSB");
? ? ? Serial.print("VCO : "); Serial.println(vco);
? ? }
? // TEST WITH SERIAL OUTPUTS --------------------------------------------T E S T?
? ??
? ? ? ? Serial.print("bfo : "); Serial.println(bfo);
? ? ? ? Serial.print("vfo : "); Serial.println(vfo);
? ? ? ? Serial.print("mult : "); Serial.println(int(SI5351_FREQ_MULT));
? ? ? ? Serial.print("clk2 : "); Serial.println(SI5351_CLK2);
? ? ? ??
Thanks for looking Joe VE1BWV |
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Re: On the subject of fake IRF510
¿ªÔÆÌåÓýNo, see comment below
The individual bought the parts on eBay, he didn't want to pay Mouser or Digikey shipping prices for such an inexpensive part: "Instead, [Ryan] found a supplier for five of these MOSFETs for $6 shipped. This was a good deal and a bad move because those new parts were fakes. Now we have an opportunity?" The fakes were 5 for $6 shipped. Ken, N2VIP |
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Re: 2 BITX-40's
To Danial Jack Chris John
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I appreciate your replies. Will get back to it with grandchildren soon as possible. Kids and big kids want a redesigned pool filtration now for a different pool. ?Soon be back at the kit. I will check them out as well as parts lists then. You folks are great.? Thanks, Ron. ?KJ4FFG On Wednesday, July 12, 2017, 17:35, John Backo via Groups.Io <iam74@...> wrote:
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Re: Mouse encoder?
I'll say that I have. You're bottom-draggin' if you're not just gonna spend the $3 or whatever for a cheap encoder. Steve Weber KD1JV won the project, but one of the challengers was also very popular (a PIC-controlled and tuned version, by?Jim Veatch, WA2EUJ - I know, I *KNOW*, who'd-a thought of such a thing!) Link here:? http://www.arrl.org/files/file/QST/Homebrew%20Challenge/HBC%201%20Winner-WA2EUJ.pdf That said - I tried it... and failed. Just never could get it to work right. I just used a cheap-o, US$3 mechanical encoder, as my 'budget' didn't need to be EXACTLY US$50. It's definitely not IMpossible. I would discourage it, mainly 'cause 'just having it work' feels so good (heh). The TAK-40, btw - I had a PSK31 contact on it (yeah, later wired it with a DDS VFO, and once it was stable I could PSK31) from Dallas, Texas all the way up to Lake Ontario, Canada. Not bad on 5W. Link (and proof!) here:? The BITX40, however - far, far, far superior SSB. I much prefer using it, particularly with the dual gel battery, 22 watt version. Mike Yancey, KM5Z Dallas, Texas On Fri, Jul 14, 2017 at 05:05 pm, Dexter N Muir wrote:
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Re: On the subject of fake IRF510
Ken There have always been claims and discussions about so-called "counterfeit components".? Some of these discussions are valid and some seem to be just one-upmanship or competition placing fake news to denigrate a competing product.? In the discussion on Hackaday they talk about obtaining the counterfeits from reputable dealers like Digikey and Mouser.? This is interesting because other similar discussions claim that we should be purchasing from Digikey and Mouser to avoid counterfeit components from Chinese Ebay vendors.? The Hackaday discussion is also interesting because they did not do any real engineer-level testing of the components to see exactly how good or bad the components might be.? It is mostly anecdotal data and opinion. Interesting observation is that many of the US and EU original manufacturers only directly support their designs for a couple of years and then license these designs for manufacture by off-shore entities like Samsung, Tom-Top, and so on. Supposedly these licensed copies are held to the same specifications as the original because the initial designer usually buys future stock for the licensed manufacturers for their own use and sale. Given all the cross-manufacturing agreements, is there really any way we can be assured that we are purchasing OEM or at least legally licensed components from reputable sources? Arv On Sat, Jul 15, 2017 at 8:38 AM, Ken Hansen <ken@...> wrote:
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Re: I don't believe it!
John P
Shielding all the audio leads is a must (IMHO). I did so on mine. I used an SO-239 connector in place of the BNC antenna connector as all my short cables have PL-259s. I used a short piece of RG-174 from the connector to the SO-239.
If you haven't figured it out already, the connectors can be removed from the connectors to the BitX board by lightly pressing in the small slot with a small screwdriver. It's impossible to un-crimp the old wires, but I found that you can drill enough of the old wires out to allow a new (solder)?connection using a #59 or #60 drill bit. I also found the connectors at my local electronics store. -- John - WA2FZW |