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New ham, Ubitx issues
#ubitx
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Well after many years of wanting to do it I finally took the test and passed with 87/100 questions! That gives me Basic with Honours up here in Canada, which means I have access to all bands.
Of course, now after being issued my callsign today while I was at work I was eager to get on the air, and finally try out the transmit on my ubitx (I've been listening for a while now). To make a long story short, I've messed something up. I think I may have blew the finals (IRF510) on my V4 board by running an unmatched antenna (like I forgot to tune it, and tried FT8). I touched the heatsinks with my fingers after a few cq calls on FT8, the first one (closest to the power plug) was cold, not warm at all, and the second one (closest to the antenna jack) was cooking hot! too hot to put my finger on! So I attached a dummy load and wired in my meter to check how much amps it was pulling, and I got 1.3A without speaking into the MIC just on key down. Idle is around 370mA which is about right seeing as I have the nextion display and second arduino board. I don't have any spare IRF510's, and I've read that the IRF520's I have wont work, but I would like to be sure this is the problem before I swap them out. To troubleshoot I tried swapping the IRF510s on the board thinking that now maybe the one closer to the power input plug would get hot, but this wasn't the case, the one closer to the antenna still got hot. Is this bad finals? or is there something else I should look at also. Thanks! Dayne VE7DNT |
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Dave Dixon
Hi Dayne, ????????????????? CONGRATULATIONS Welcome to the amatuer radio club its the best in the world youll find people on here are very helpful..Regards Dave G0 AYD.. On Tue, 14 Jan 2020 at 06:33, dwhacks <waterlowphotography@...> wrote: Well after many years of wanting to do it I finally took the test and passed with 87/100 questions! That gives me Basic with Honours up here in Canada, which means I have access to all bands. |
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Mark - I think he does. says
Attaining honours scores (i.e.?80% or above) on the Basic examination, or attaining qualifications in addition to the Basic Amateur Certificate will grant the amateur certificate holder additional operating privileges as specified in , including full access to the amateur frequency bands below 30?MHz (i.e. high frequency?(HF)).Dayne - FT8 (among many digital modes) runs the radio pretty hard, since it transmits for long periods of time with lots of modulation. Definitely a good stress test, but unfortunate that it may have overstressed one of the amps. I'm not sure what input voltage you're running at, but you could try reducing your input voltage, which will reduce the final power, and subsequently put less stress on the finals. I haven't measured my v6's current, but both of my finals get warm fairly quickly when I continuously transmit into a dummy load, so it definitely sounds like you may have an issue. Reed |
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Andy_501
开云体育Only question that comes to mind is does the UBITx kits fit into
"commercially built & certified"? category or "homebrewed" ??
because Basic-Plus requirement also requires gear be commercially
built and certified. Unless the kit is built but certified by an
advanced amateur as complying with ISED Eng specifications for
operation???? On 2020-01-14 1:57 a.m., Reed N wrote:
Mark - I think he does. saysAttaining honours scores (i.e.?80% or above) on the Basic examination, or attaining qualifications in addition to the Basic Amateur Certificate will grant the amateur certificate holder additional operating privileges as specified in , including full access to the amateur frequency bands below 30?MHz (i.e. high frequency?(HF)).Dayne - FT8 (among many digital modes) runs the radio pretty hard, since it transmits for long periods of time with lots of modulation. Definitely a good stress test, but unfortunate that it may have overstressed one of the amps. I'm not sure what input voltage you're running at, but you could try reducing your input voltage, which will reduce the final power, and subsequently put less stress on the finals. I haven't measured my v6's current, but both of my finals get warm fairly quickly when I continuously transmit into a dummy load, so it definitely sounds like you may have an issue. |
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Dayne,
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Mark could well be correct.? If RV2 and RV3 got twiddled with, that fully explains this. The fact that the problem does not move when you swap the IRF510's suggests the IRF510's might still be ok.? If you can adjust each IRF510 for 100ma of quiescent current, then you know that they are ok.? Be careful when doing this, RV2 and RV3 (also RV1) are? backwards from normal pots, fully clockwise is minimum.? Adjusting RV2 and RV3 will have no effect until somewhere around 4 volts at the IRF510 gates when suddenly they are very sensitive.? Adjusting them a bit too far and the IRF510's will draw too much? drain current and get hot very quickly. Measure the voltage at each IRF510 drain, should be around 12v with no audio (no need to press PTT). If not, then the choke (L8 or L9) or a copper board trace in the path between the drain and the 12v power supply has failed on the cool IRF510. With PTT down, should see around 4 volts DC at the gate of each IRF510. If not, then something in the path between the LM78L05 at U2 and that gate has failed, perhaps RV2,R97 or RV3,R98.? Also possible that CV2 or CV3 has shorted on the cool one. >? I got 1.3A without speaking into the MIC just on key down. Idle is around 370mA That 1.3A seems high.? I assume most of the extra 1A is going into the hot IRF510 drain. I'd find it less confusing to measure just the current into L8 and L9, should be 100ma each with no audio when RV2 and RV3 are adjusted properly To do this, you will have to unsolder L8 and L9 to separate them from the 12v supply. At any rate, I think your rig is very close to fully functional. Spare IRF510's are cheap, and worth having on hand. Buy from a reputable dealer such as Mouser or Digikey (or a local ham), some of the ebay IRF510's are random power NFET's with a fake IRF510 label. Gate capacitance must be extremely low to work well at these frequencies. > Unless the kit is built but certified by an advanced amateur as complying with ISED Eng specifications for operation???? With 5 or 10 watts out, these fine lines are not something I'd worry too much about. Regardless of regs, not a bad idea to have an experienced ham have a look at it. Should be able to find somebody willing to take a look by checking in with a local club. Quite possible somebody local could loan you a working rig to get started with, or have you as a guest operator at their station. And if they are overly anal about this "certified" thing, perhaps they can help you toward an advanced license. Jerry, KE7ER On Mon, Jan 13, 2020 at 11:14 PM, Mark - N7EKU wrote:
I would redo the bias setting in the finals. There should be instructions for that on ubitx.net or on the list here.? |
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Andy_501
开云体育I was a volunteer examiner here in Canada for our rural locale
and Basic Plus gives a successful candidate access to all bands
including? HF bands below 30MHz with power limitations and using
commercially built gear. Not until the candidate attains advanced
amateur qualification are they allowed to own and sponsor
repeaters or other remote access equipment, use homebrew gear, or
run full authorized maximum power. It is why I was putting forth the idea to a local club that runs
advanced courses to see about including a lower priced QRP
multi-mode all band transceiver kit as part of the practical lab
component to the course. In such a case they would hopefully
attain advanced privileges and attaining the OK to operate on home
built gear as it were. Should they not pass on the first try they would have gear that was checked by advanced amateurs conducting the course their first time through and certified it met specs and thus possibly considered in the same class as the required "commercial gear" rating until they could re-take the advanced test with success. Don't mean to be a nit-picker; just didn't want to see any noobies get into troubles with the powers that be. Cheers & 73 Andy On 2020-01-14 1:14 a.m., Mark - N7EKU
wrote:
Hi Dayne, |
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I tried to re adjust the two bias pots by following the ubitx guide. It says to first turn them clockwise and measure the current, when doing this my total current consumption in 1.2A (some searching says it should be 300-500mA depending on mods), which is quite high. So I put my meter on the brown power wire only (PA power) and the lowest setting I can get is ~900mA with the bias pots clockwise. Idle current is 0.
I am running the ubitx on 12v. |
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Andy_501
开云体育likewise I wondered about? remote amateur systems like echolink or teamspeak3 granting full transmit access to a basic or basic-plus qualified licensee from Canada
On 2020-01-14 10:09 a.m., dwhacks
wrote:
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Andy_501
开云体育Likewise would repairing your own faulty ICOM or Yaesu gear not fall into the same category? Changing the PA's as an example could result in some nasty parasitics that could interfere with another EMER or ATC service etc and without have the work done in a certified repair shop or confirmed and certified by an advance amateur puts it in the homebrew category as well one would think. In Canada the previous "pro-active cooperative resolution system"
for RFI and other interference resolution has been removed from
govt inspectors and thrown into the adversarial court? systems for
settlements in worst case scenarios now; privatized to reduce
inspector workloads that justified budget reductions. So it isn't
the smooth process it once was. In the extreme it is possible a
previously easily resolved issued could rapidly approach a
D.A.R.F. on steriods situation. Something a noobie is not likely
to welcome as experience in a new hobby they just want to enjoy. On 2020-01-14 10:09 a.m., dwhacks
wrote:
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Legal risks are not something I would worry about, especially at QRP power levels.
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Cease operating if you get a complaint, verify your equipment is not at fault before resuming. If that's too much risk, you'd best stay in bed. Most of us take far more risk everyday when we get behind the wheel. Or make our way on foot using a crosswalk. Jerry, KE7ER On Tue, Jan 14, 2020 at 08:44 AM, Andy_501 wrote:
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Dear Jerry, KE7ER
You are exactly the kind of person I hoped to encounter in Ham radio. I love DIY, and I love the sharing of knowledge. This is was brought me to the uBitx. Also, your post was the PERFECT step by step guide to finding my problem, and solution! So, I don't know if anyone has noticed on the V4 boards, but RV3 is crooked from the factory to clear the heatsink. Well, somehow, over time, one of the legs on that trimmer broke so it was now feeding Q94 with around 5v! no bias adjustment possible! All I had to do was swap it out for another one and we are back in business! set the finals to 100mA each and all seems good! Thanks again from everyone who chimed in. I have asked the Ham that did my exam and he said, as far as he reads it, the ubitx falls under "assembly of commercially available transmitter kits of professional design". I will get him to check it over anyway, but I'm not about to stay in bed afraid of the world. I will also be studying towards my advanced, as homebrew QRP is what I am most interested in. Thanks again, Dayne, VE7DNT |
