On this channel I'm going to share videos related to my hobbies, and even my work. My aim is to make videos that you might learn something from, or make you crack a smile and laugh - Either with or at me in the process. ;-)
Content may include musical instruments, Amateur Radio operations & equipment, Automotive maintenance, and general lets see what happens if....
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I have a USDX white buttons it works great as a receiver you know AM and SSB but the SSB transmit audio quality is unintelligible. I've tried changing microphones, modifying the PA bias min, max, noise gate, TX drive and still SSB transmit is unintelligible. I've read that updating the firmware to the latest version helps SSB transmit audio quality so I ordered the Arduino Uno and the cables... we'll see if the transmit audio quality improves. I may have to program the SDR radio myself to make the transmit audio quality sound good, other comments underneath this video indicate that the SSB transmit signal is not true SSB or that changes in the circuitry are emulated in the SDR....well I'm going to look at the firmware code....i think you can modify the digital filter design coefficients and the like....oh one last thing...the output amplifier is Class E meaning that it attempts to reconstruct the output RF signal using switching, sort of like how switching power supplies construct DC output by filtering the output of a square wave.
Would you please show, with better light, the fix you did on the speaker jack on the rear panel? I would like to do that as well but need a clearer picture. Are they just jumpers from one side to the other? Also, is there another value of capacitor I can use for the processor fix? I can't find any 47nf disc ceramic caps anywhere, not even DigiKey. Thanks, Tom. Doug VE7DRF
Hey Doug, so the capacitor that I used on the header is just a run of the mill Ceramic disk capacitor that you can buy off of Amazon in a bulk assortment for $15,. I used a 47nF, and it is over-kill. Two others I've worked on sounded better with a 10nF capacitor installed. www.amazon.ca/10pf-Capacitor-Multi-Layer-Resistance-Assortment/dp/B07RWM9TMN/ref=sr_1_2_sspa?crid=2S66BFC1UKI7K&dib=eyJ2IjoiMSJ9.qBNfiB-Mnah2LuthN077qKv5aT23XiaDdGyIkx9OSuOFmwzbt3zP8mVLcDqxommNx7hLUrXTmu5JjDKhwhHuIuFTnLSIDXFGkoO2U-8RcnmkUXrZ-8BCbAMoSWOj6N2GXFAVtQ64ji627k6NHcs5TL2-ltapeHAgm-ap0vnC7UCEAOIivwQdrCFaN0IbKhUUyMjh45bfT81GYwh7nxZBX6aeZLa9ULaQd77dvgO9hiiWmKlxWDPUahuSvc8f3cLY1pY1pJzsoW0Brrcb5lKPxNQxu9QXwymzsqDLZ70l0N4.rhwtd1RAsGLKj_75woU5XFLE04FPi11hrpwY-_00EmA&dib_tag=se&keywords=450pcs+multi-layer+ceramic+capacitor&qid=1719961429&sprefix=450pcs+multi-layer+cermaic+capacitor%2Caps%2C161&sr=8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1 As far as the jumpering of the speaker portion of the k jack, The radio is now well and truly built into its permanent station, so I'm not really wanting to take it appart again, as it is working well enough these days. You might be able to hear me on the Aurora Net from time to time. :) With that said, of all the video and pics I had taken the best did make it into the video. But yes, essentially it's just two wires jumping across to the opposite side of the jack. 73 Doug -Tom VE7NGK
@@tomsworkshop5856 Thanks for the reply, Tom. I think I'll forget about the cap replacement. I don't plan to upgrade the firmware, at least not at this time. I have installed the 100k resistor at R23 and done the jumper mod so all is good for now. I'm gathering the parts to build an EFHV antenna to try out using the uSDX+. We'll see how that goes.
@@dougkathydavies3024 You know, I've got a few radios. I love to rag chew, and one of them I use on 80 meters every night, and it sounds good and everything. But the uSDX+ V2 is now installed at my place of work, and gets used at coffee, lunch and after work times. I've hunted 187 parks so far, armed only with a 60' random wire, powered by the OGS-50W amp, and the ATU-100. Out of my fleet of radios, this little thing has become my favorite. I do plan on posting a follow-up video of some other things you can get/do to get the most out of it.. So stay tuned, and good luck! I hope to hear you on the air one day, and hopefuly soon!
I bought one of these a couple weeks ago, and I made sure to buy it on Amazon instead of any of the dealers on AliExpress. It cost me a little more this way (I paid $132 from Amazon), but I'm glad I did, because now I can RETURN it. The radio I got is basically deaf - it can hear noise, but nothing else. Not WWV, not ANYTHING on 20 or 40 meters. And no, I'm not going to spend 40 hours on trying to make it work, because I am convinced that both the uSDX+ AND Manuel's (tr)uSDX are junk. Not just bad construction (although this may be worse on the uSDX+), but by design. I actually bought the (tr)uSDX first, from the approved vendor on Amazon, but apparently I didn't read enough reviews first, because i was disappointed in its performance. Guido, who wrote the firmware for all of these radios,, started off by modifying a QRP Labs QCX transceiver, which is a CW-only radio. He replaced most of the components in the receiver circuit that were doing an image-rejecting detector, which includes among other things, several op-amps and associated resistors and caps to shift the phase of the demodulated signal so that the undesired image signal gets canceled. This Guido replaced with code, doing the phase shift in the firmware. But he went way further than that, cleverly finding a way to produce SSB modulation without adding a lot of circuitry - again, he does this in software. I won't go into detail, but he takes the mic input, which goes through that phase shift network, and does a little more math on it to convert it from an I/Q signal to separate phase and amplitude signals. The phase he deals with by doing real-time small adjustments to the frequency of the Si5351A synthesizer chip, and the amplitude he fed to a transistor that was being used on the QCX radio to amplitude-modulate the keyer signal so that the rise and fall times of the RF aren't so sharp that they cause unpleasant key clicks. Which apparently worked all right, BUT, after some testing, he determined that the amplitude modulation isn't completely necessary - if you disconnect it, you get what sounds like highly-compressed audio, because that's pretty much what it is. And then he doubled-down on this, claiming that disabling the amplitude modulation actually improves the readability of your signal when it's down in the noise. Which of course is true, but it's not something I want to have disabled all of the time. Well, too bad, because he actually removed that circuit from the (tr)uSDX design. It LOOKS like he may be doing a slight amount of amplitude modulation by changing the DC bias on the FET gates (that circuit that you showed that had the missing 100 kohm resistor), but it's not nearly as effective. I even read one review that says that unlike TRUE single-sideband, where you only produce RF when you are talking, this radio puts out the same amount of power whether you're talking or not! I found this unacceptable, but I thought that maybe I could just add that proper modulation circuit back to the radio, and modify the code to make it work like it did in the earlier versions. So I looked on Manuel's forum to see if I could get the source code so I could fiddle with it and make it more like REAL SSB. I found a post where someone had asked essentially what I was going to ask, but he asked instead if he could use the source code from the uSDX project on the (tr)uSDX. Manuel chewed him out, accusing him of "software rape". Literally. I wrote to Manual, telling him how inappropriate this was, and also that I have no use for the firmware if I can't modify it for my own purposes. This IS amateur radio we're talking about, not commercial radios. But no, he chewed me out as well. So I thought, okay fine: I'll buy one of those Chinese uSDX radios, because at least then I would have the amplitude modulator circuit. Well, that turned out not to be the case; the design that got ripped off and built by several different Chinese manufacturers uses a later version that also does not have the amplitude modulator. And besides, as I mentioned at the start, the receiver is pretty much useless as well. So here I am with two useless radios, but at least one of them (the uSDX+) I can return. The (tr)uSDX I bought in kit form, and at least it works, but I'm probably never going to use it because I WON'T use it in its present form because what it produces is not SSB, but more importantly, I can't modify the code to make it work with a proper modulator because Manuel believes it's HIS radio, not mine. Not at all happy, and now I'm working on re-designing the whole rig because it's such a hack job to begin with. That is, starting over from scratch using a microcontroller that's up to the task.
rest easy you most probably did not blow it up. there is a problem in the design. You have a better shot of winning the lottery than getting one that is good and not need to be McGyvered
Being this is an open source design you could theoretically re design the filters in the PA stage. However, being MARS operations require reliable equipment, with skilled operators this radio should never ever be used for that service.
Tom's Workshop, Here is a link to a video you may or may not have seen yet, I found it very informative of the USDX design... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Uv5xgX6MzQU.html Thank You...
I just got my usdx+ and it has no reception on all bands. I am using long wire antenna. Compared with tecsun pl330 and the same antenna, reception is very good on this little reciever. Has someone had this issue? I did a fix with connecting the ground to the case only. Did not solder the resistor and capacitor yet.
That’s very odd. I’d make sure the noise filter and attenuators aren’t turned up. But that would be a new problem I’ve not run into. All 3 of mine can hear a pin drop on the far side of Mars.
Not only might the amp create those emissions, but the radio's own spurious emission will get amplified. And it only takes a small signal that's not resonant with the antenna to cause artificially high SWR readings. The difference being that the amp usually won't blow up from a secondary or even third harmonic that's 45db down from the main signal. ;) But filtering is definitely needed.
I bought on sometime ago, and promptly forgot it ! Decided I needed a small tuner, and luckily, or not (?) remembered where I left it ! Plugged it into a charger, and so far nothing ? Thought it might at least light up, but nothing so far ! Waiting for the Two hour charge cycle as described here, fingers crossed ! Are the only indicators for charging, when you switch the unit on ? I scanned the QR code on a card that came with it, but says in it's no longer available ? So Zero instructions, etc. ! Any help appreciated ! Thanks in advance !
Well, this is an interesting one indeed. So, you have a couple of things going on there. Since it may have sat for a very long time, it is possible that the 3.7 volt lithium ion bettery has bit the dust. It's a small pouch battery glued to the shell of the unit - right beside the charge controller and boost converter. The tuner runs on 12v, and thus the converter boosts the voltage from the battery. Due to a bad design, this boost converter is always on, and always drawing a few milliamps of power. After a few weeks the battery is dead. After a few months the battery is shot. With that said, on that board, inside the unit are 2 indicator LEDs. One red for charging, and one green for full. When a correct USB cable is plugged in, it should charge, or at least create the 12v needed to run on the tuner. If this does not happen, make sure you are using a dumb 2.1a USB block, and the dumb USB-C charging cable. Fast charging blocks and data USB-C cables do not work with this tuner. (Like many cheap Ali-Express/Amazon toys with such power in ports. If this doesn't help, I'd suggest removing all the battery related stuff, and putting a regular 12v supply to the unit. As the base tuner is actually a decent design. Hope that helps! 73 Tom
@@tomsworkshop5856 Yes Tom, thanks for getting back ! After giving it a few hours charge, it lit up ! So it seems to work, to a point ! It seems to function on A.M. and SSB, but switching to FM, it seems to shut the tuner off ? Using a very old 25 watt Radio Shack HTX 10, which I think is running less than 25 watts ? Running into a 2 foot helical mag mount on my truck. Have made contacts so it seems to function, but I don't understand it kicking out on FM ? I installed a common mode choke on the antenna lead thinking some RF was getting back ? Still more to do ! Also tells me I've reached Max Power, if I whistle it up on SSB ? Not running anywhere near the 100 watts I thought this was rated for ? Any thoughts ? Thanks !
Ya, they do have some quirks to them. The FM shouldn't really bother it. I've done some FM work with mine at 50 watts. One thing they do suffer from, and causes the screen to crash is bad grounding. I'd make sure everything is well grounded. !! I also never leave mine in auto mode!! It goes stupid at higher power, when it starts a tune cycle, and gets above 9:1 SWR it will show 100s of watts. And at that point you can easily fry your finals !! There's also issues with the quality of diodes used in the SWR bridge, which is the heart of the unit as power and SWR gets reported to the CPU from there. I'd do a google search for ATU-100 diode replacement. Good luck, brother!
@@tomsworkshop5856 Thanks ! Well I know more than I did ! Lol ! I bought the thing some time ago, and kind of forgot it ! And as typical, no instructions to be found that I know of, so just been following my nose ! Thanks again Tom ! '73 !
Hey, well, there's so many different antenna combinations available that it really does depend on what you're planning to do. Set it up in a car, take it out into parks, or set up some sort of home station. I'd suggest doing some searches for HF antennas on here. There's lot's to learn. I hope that helps. And, depending on time, I do want to create a video about the random wire antenna. (You'll need a tuner to use one,) but they do an OK job across the all bands if you get them set up just right. If you're new to the hobby I'd suggest contact your local ham club, they are always wanting to talk and help new comers along. :) 73! Tom
Yes, I can see were you coming from. The Chinese copy only good designs. It is the enthusiasm of people having a problem and doing research and development and come up with a new product. A good engineer needs this ability of having fun in understanding things and a child like attitude to improve it. Ones in the process you can't stop, you have to go on. Unfortunately in our world everything gets messured in the equivalent of a value of money. A good engineer is not necessary a good salesman. I can understand, I am also an engineer. Can I raise a question? The radio amateur is more and more a consumer. There is a whole industry trying to sell stuff to hams. This is a very sad development. For many years every radio amateur was a developer and researcher. Today he is a consumer with the industry getting more and more power over hams. We are on a point now where you buy a "black box" without documentation. You buy it like a can of beverage and recycle it after use.
You have summed up the average new ham radio operator very correctly. There are some of us that still love to play, fix and make better. But for many, that would be too much to ask. With that said, I know of two new hams that are less than 16 years old, that have bought tubed equipment and fixed it, ground their own crystals. (thanks to RU-vid instructional videos) and are having more fun with old junk than new radios. The fun for me, is when Chinese junk and old junk get together for a QSO. ;)
I've used the Hand held Baofeng mic with it, but got reports that it sounded very bad. Now, the little ear piece/microphone one that comes with the UV-5RE is one that I think would work very, very well. But I was hoping to find it, and try it before commenting, but I think I must have left it laying on a park bench somewhere. Hope fully someone else has one, gives it a try, and let's us know.
I ordered the PA50+ online, and they sent me one of these. Granted it was a great price, and now I know why. The one I got does look different than the one you have shown. They have added 3 large resistors to the board, 2 of them are 420 ohm, one is 120 ohm, so I wonder if they have tried to fix the input VSWR issue. I couldn't get a chance to test it as once I applied power, the power light came on for a brief microsecond, then something in the amp shorted out, so I started a return.
Wow, definitely worth returning if it only had a millisecond life span. But most interesting that they are still working on ‘improvements.’ Hope you end up getting a working amp in the end. 73
Hi, I have recently received one of these with the extra resistors. Measured at 43 Ohm and 12 Ohm. In PI network theoretical attenuation nearly 9 dB and return loss of about 7dB, equivalent to a VSWR of about 2.5:1. Supposedly better than previous. Just waiting for replacement MOSFETs as the smoke escaped when checking bias voltage. Cheers Peter VK7KPC
Hi. I take today the usdx+ v2 and the amplifier. I want use with atu-100 like you but not tuning. Needs 10w and up. When i use the ldg z100 tuning (i listen rele and green led show tuning) but the bridge say 7-8:1. Any idea?
i have bought the usdx+ V2 and the ogs-50 and i have the at-100 tuner. on the usdx I connect the ogs-50 and then the tuner. correctly? how can i tune without transmit 50 watts to tuner? can i add a switch to the amp to turn it off when tuning?
So, you've got it set up correctly! With the amp un- powered, you tune the antenna, and then connect power to the amplifier. I've not installed a power switch into the amplifier, but there is a video on here somewhere where someone installs a magnetic power switch inside the amplifier. I just pull the power cord out of the amplifier when I'm not using it, but yes, a switch at the battery or power supply would be very much helpful. For those following along the connections are: Radio out to amplifier in, amplifier out to ATU in, and then ATU to the antenna.
Hi & thanks Tom, If I understand correctly the maker or designer of the amp did not allow the input side on the amp to appear as a 50 ohm load to the source radio, correct? Because I did not open the case yet I just want to be clear about where I connect the pair of parallel resistors. I saw the proper location on the relay so I am good on that. I believe you said for the other the ground tab of the two BNC connectors, correct? I guess the two connectors share a common ground tab, but as long as the connection is made to what the connectors ground to should be fine, correct? Also, how critical are the 200 ohm in parallel =100 ohm 6 watt resistor assembly values? I'll probably have to order them anyway since 3 watt resistors are not typically in my build box and I am wondering if it was just a workable value you had and perhaps there is an even better selection. Thanks again....
Yes sir, you've got it right. However, there's a different version of this amp being sold now, and it is identifiable by the blue power light instead of red. I recently bought the second version, but have not yet been able to do the modification as they went through-hole for the relay. I'm hoping to make a follow up video on this newer version as to how the modification can be done, because, well, it still doesn't present a good 50ohm load to the radio. Hope that helps!! & 73
@@migalito1955 Sounds good, hopefully this will be a simple (ish) mod, I do know I need to pull the board out, and that means the temp switch and unbolting the FETs. So, might take a bit of effort, But I'm hoping to find some "top side" connection point after I go through it. We shall see.
I bought one too. I also like it. I was aware of it not having reflected power protection, so I am only using it on a resonate 40 meter inverted V in NVIS configuration that also has very low SWR on the 15 meter band. At the moment I am using it with either a bitX-40 or early ubitX. Each does not have adjustable power so I power the transceivers with 9 volts at 2 amps max that allows the rigs to output about 0.8 watts of signal which combined with the amp becomes about 28 to 30 watts. So far no issues. I suspect but don't want to push my luck that my low input allows for a little bit worse than 1.5 SWR for maximum SWR. The only thing I noticed is the relay that switches from receive to transmit has a lag of about 200 miliseconds. I only use SSB so to avoid being initially cut off I tap the mic or otherwise spoof the start of audio. I will take a look at your SWR protection video.... 73 from kc2wvb
Great video Tom on making the usdx a better radio. I know you didn't want to get into the firmware update, probably because of added issues after updating it. Is it worth to doing a firmware update or just leaving it the way it is? If so, which firmware update do you recommend? Thanks, Martin.
Hi Martin, thanks for the kind words! So, all of my uSDX+s are running 2.00c, and it seems to work rather reliably. I've also heard, but not tried good things about 4.00c, with 4.00d soon to come out on the Facebook group for these radios. 73, Tom
It was open source. No violation. Also you bought a second version of this radio which was known to be bad. The original company had stopped making these. You should have done your homework before buying it. I own two of the original versions of this radio and have worked all over the world with fine audio reports.
Well, and that's the reason for this video. For others who are doing that research. I now own 2 of these radios. And, like you, I get glowing signal reports, now. The original one featured in this video is in daily service, and has logged many, many contacts, and has even done net control duty. As far as the legitimacy of this radio, and all those based on it's foundation. It could truly be called a disaster with the licensing changing in mid flight. Not to mention the addition of clones of clones. But I'm glad you are enjoying yours as much as I am enjoying mine.
Thanks, Tom. It is so funny how clones of clones of clones show up. Sadly, they get worse as time goes on! But it is great how popular QRP has become. I started in 1968 and there was never talk of it. Thank you for telling guys how to fix the later versions.
I've heard this a couple of times, but mine does seem to do OK and 15 12 and 10, for as often as those bands have been open for me.. So I'm not complaining.
That's a tough question to answer because everyone uses VHF a little differently. If you're just looking to boost your handy talkie a bit, then Btech (Model # AMP-V25) makes a nice little amplifier that also has audio (in and out) to turn your handy into more of a mobile / base setup. If you're looking to do VHF SSB, AM, or Digital then I'd be suggesting that you look at the offering from RM Italy. Hope that helps. 73! VE7NGK
i just got one of these, after watching your video i decided to tear it apart and lo and behold i'm also missing that resistor! I've only ever done through hole soldering so i guess it's time to learn smd. I haven't noticed any issues with grounding like you mentioned although mine is in the same anodized case. i might still do what you did just in case and ground the sleeve to a screw. the one problem i've noticed so far is that when in cw mode, my sdr dongle picks up tones from the uSDX. Both devices are sharing a single antenna and i'm not sure if that is causing abnormal behaviour but since i have yet to get my technicians license i'm quite nervous about accidentally transmitting. i guess the only thing to do is run some tests with an oscilloscope and see if it's acting up and then consider returning it and getting the trusdx if i can't resolve the issue.
Good day!! And congrats for holding off transmitting until you get your appropriate license. :) If you're planning to use this radio for CW, you will not be disappointed. The odd behavior comes into play with using it for sideband, and not all of them suffer from it. If you can get the (tr)usdx, you'll have a much more enjoyable experience, especially if you're not comfortable with moding the uSDX. But, yet again, I don't know what you paid for it, but if it was cheap enough, it could be a good learning opportunity. As far as sharing an antenna with another receiver, that's really not the best idea at all, as it will blow the front end out of the other receiver with ease if you transmit without some sort of duplexer... (And that would be a feat to create for HF, IMO.) If you're just receiving with both, then yes, the uSDX will create some birdies that the other receiver will pick up. I know that when mine is tuned around the 80 meter band, it will break the squelch on my VHF receiver. But they are very localized emissions.. All the best!!
If that not work (to small to get solder, you can try a axial model 100k, if done that l, it works perfect, and nice in place. Thanks for the video and the improvement ls you made Tom I have done all '73
I have one of these, but didn't realize it was a clone until I had purchased it. It is basically ok for what I paid, but if I had it to do over again, I would buy the real thing. In fact, I probably will purchase one of his soon. Manual is a great guy and deserves the money. Thanks for your time invested. BTW, do you have the firmware link?
Well, if you're looking for the latest, I'd go over to here: github.com/GW8RDI/uSDXOpen?fbclid=IwAR0MN9C83QCF1Jqf92JiBB5VGB2yIvysUgtn6yr5L_Do7c2wAiihL5JjIC4 I hope that helps!
Same here, mind you mine kind of works OK from new, same issues the grounding I fixed using copper foil, added the capacitor, waiting for some smd resistors.
Keep the vids coming Tom! I really appreciate your support on this rig! I added your improvements, and it has made a difference. I’ve had a lot of fun so far, making many cw and ssb contacts at very low power. I think the best I’ve seen, is 3.5w on 40m and maybe 20m. I love to tinker, but need a little direction. Thanks again!
Thanks Trevor! Mine has become my daily driver for lunch and coffee breaks at work. Way too much fun when you finally get it to the acceptable point. :) 73!!
So I did the mod and it sure made a real difference in the swr presented to the radio. So far I only tested with an usdx and the reports were bad, to say it mildly. I dont think the usdx is anywhere near a finished product, and thus it does not like this amp it seems. I could test the PA with my 817, but the risk and the pain involved in renewing finals on the sweet little Yaesu makes me a bit reluctant to mate these two. Maybe I am overcautious... I dont have deep experience with practical electronics but is there any way this amp could be put to work? Any bands with less unwanted emissions? 10-15-20 meters maybe ? Simple filters?
Ya, the USDX is a pain. And the 817’s finals are fragile to say the least. As far as making the USDX almost useable, check out my other video. And search Facebook for the USDX group where you can find better firmware and how to upload it to your radio. Mine’s doing OK now, but dang, RF getting back into it via any connection, power, mic, etc.. makes it sound very bad - and adding the amp really compounds the problem. It seems, for me at least, I get the best results on 20 meters. I hope this helps, brother. 73s!
Great video Tom. Lots of true words spoken. I bought one of these and it arrived last week, already I wish I had bought the tru version. I think I have the same instability problem you experienced and was putting it down to a noisy BNC connector, so at least I now have a head start. Mine seems to work well on 20 and 15 but 40 and 80 have some sort of problem on receive that sounds like the recovered audio is being restricted by around 75%. I will start pulling it to bits soon and if I find a solution will post. I am intending to buy another, but for sure it will be a Tru sdx this time. Thanks again. Subscribed. 73s Shane. G7EWL
Thanks! 40 and 80 have weird sound to them on both my radios this week. Most of the folks I talked to on 80 last night were commenting on the after effects of the geo storm we had last week, so may don’t do anything drastic just yet. ;) Also, the Noise filter / blanker (NB) setting seems to work more aggressively on the lower bands. (On mine, anyway.) All the best!! Tom, VE7NGK
Two things come to mind. Drive power should be 2 to 5 watts, and if you're using an mcHF/RS-918 type radio, (Or similar experimental radio,) harmonics. Often times the 3rd harmonic.
@@tomsworkshop5856 Hi Tom, thank You for your answer. Yes, the drive power exceeded 5W - in fact it was around 6-7W. But would it make such a difference? Today I tried handheld Albrecht 2,5W and USDR reduced to similar power. The amplifier gave 40W on output , and a few qso-s were made with good reports. Harmonics - yes, but would it not affect SWR (and it was exactly as expected)? Anyway - best regards - Maciej SP5ZE
@@user-nc6gw2se6x They often do effect SWR, but in some cases, especially with non-resonant antennas that are being made to transmit with a balun or unun, such as the popular 9:1 random wire. The SWR, even with out a tuner can often be under 2:1 on all HF bands, thus, the harmonic(s) might not affect the SWR as you would expect. Now, if it is a mono band antenna, I'd be surprised. But, not everything works out to simple answers. Also, I often run my amp in excess of 75 wats on 80 meters. It gets warm, the fans run a lot, but it seems happy doing that. ;) I just wouldn't recommend doing it, if you don't have replacement IRF530s on hand.... All the best and 73's VE7NGK
Appreciate the video! However, I set up several jigs with two samples of this amplifier, and loaded it with both tuned antenna and dummy loads, and measured the VSWR on the exciter (a (tr)usdx) on all bands, with the OGS either powered on or off. Worst case was on 80 meters, and was approximately 1.5. Best measurement was on 11 meters (no surprise). I could not repeat your observation. Can you display the actual test setup you used? Also, I would be very uncomfortable using this amplifier without some filtering. It is sending large spikes at the second harmonic, on all frequencies measured, making it unacceptable as an out of the box amplifier, even for 11 meter operation. Wonder if the manufacturer has something to do with the problem: different stores in China have wildly different pieces with the same name. Not doubting your findings! Just want to know what accounts for your findings. Again, thanks for all you do.
Good day George. So, I've stopped using my uSDX with this amp as it creates far too many spurs and harmonics. The class E final setups in those radios are not up to being connected to an amplifier at all. I've exhausted many hours trying to clean up the emissions. With that said, I use this amp with my RS-918, that has had Wayne NB6M's modifications done to its filters. The OGS-50W is a dumb amplifier, and has no input loading, thus, unless they've changed something in the last year, I'd wonder how you got a good match at all. (And I'm not doubting you and the fine manufactures change things everyday!) The tests I did used the SWR meter in the RS-918, confirmed with a direct connection to a dummy load (Showing 1:1ish) and my Random wire without tuner (2:1) and then tuned 1.06:1 Using my ATU-100, and the OGS powered off in between the radio and tuner, and repeated on all bands. Once the the amp is powered on and trips into transmit, the reported SWR on the antenna tuner stays low, 1.15:1 (Some change expected with the increased power, and resistance of coax, balun, etc.) However, the radio's indicated SWR (5:1) was so high that radio was only pushing 2.5 watts into the amp, while set to 5 watts, in many, but not all of the bands. There is good news: The harmonics detected from the output of the antenna are 40 to 50db lower than the fundamental, compared to 9db lower than the uSDX substituted for the RS-918. Test set up was TinySA, using supplied antenna polarized in the same direction as the random wire and 40 feet from center of that transmitting antenna, with the TinySA set to measure harmonics. (Notably the 3rd harmonic was the worst in all cases, with both radios, likely because the amplifier favors frequencies in the 10 to 15MHz range.) So, you are correct. If your radio is dirty, or has high DC out, such as the uSDX families of radios. (This is evidenced by the uSDX radios only generating about 30 watts out of the amplifier, but traditionally built commercial radios without the DC component will do 55 watts with the same 3.5 watts in.) Don't use this amp without a filter system BEFORE the amplifier, unless you've cleaned up your radio's emissions to all harmonics being -50db or better. A filter setup after the amplifier is a good idea, but if you haven't cleaned up what it is amplifying, you will be converting all of your output to heat in the filter network. It should be noted that it will work on 10 meters, or as you say 11, but it is super inefficient. I hope that helps, and all the best to you!
@@tomsworkshop5856 Appreciate the thoughtful reply. I will set up the OSG-50 with an RS-918 (one of my favorite portables!) and see what I measure. My measurements were with the SWR meter and transmatch at the base of the antenna. The OSG-50 was left inline, both powered and unpowered, and worked well, with many spurs noted, which likely reflect the Class E operation, as you noted, of the (tr)usdx. I use an LPF-7, as well some other stiff filters on most of my Chinese equipment, as the second harmonics are often troubling. I am a product of the early sixties amateur scene, and recall "pink slips" for inappropriate emissions. All said, this amplifier is a work in progress, and needs a bit of work to be a good ham radio product. V73 George KF5WFA
@@plotdoc Hey, Thanks for the kind words! I do agree, the amplifier is a work in progress. BUT, I can say I've now logged over 100 hours of TX time on it. So, at $1 an hour investment, seems to be rather good. lol All the best George!! 73's de VE7NGK
@@tomsworkshop5856FB, Tom. I set up a test rig, using a QRP SWR/Wattmeter between the exciter and the amplifier, and another SWR/Wattmeter between the amplifier and the load, which, for purposes of the test, was a Cantenna KW load (finally, a use for it!). With the exciter active, and the OGS non-powered, the forward power was set to 4 Watt, and was seen on both power meters. SWR stayed at 1.1 or better, on all bands, from 160 to 10 meter. Then I energized the OGS with 13.8V, and repeated all the studies. You are correct, Tom. The reflected power to the exciter was several Watts, making the VSWR nearly 6! The lowest value, 4, was obtained on 15 Meters. I will certainly try your fix, but excellent pickup on this one, OM! 73 George de KF5WFA
@@plotdoc I honestly can't take credit for finding this. But, once it was brought to my attention, fixing it made a world of difference. It's possible to use two 100 ohm resistors to make things happy, but the amp suffers. (I tried) So, the end result is 2:1, and the amp doing its job. Kind of a compromise, but a good way to not hurt your radio. (The amp's finals are easy enough to replace....) Have a good one friend, hope to talk to you on the air. I love 20 meters on Saturdays. ;)
I don't want to be hypocritical, but now that I've got mine working, I'm really enjoying it. Ya, it still sounds not 100% on TX. But it is a hoot. Its receiver is much better than the one in the RS-918, (mcHF) and even better than the one in my Yaesu FTDX401B. (All tubed.) So, it's got some good points. I hope that you can get yours working, as I tend to have a very good signal into your part of the world on 80 meters. But that tends to not happen as often as I'd like due to work. It could be fun to chat uSDX to uSDX! You can find me often on 3.968 7pm evenings and 7.230 Sunday afternoons helping with the Western Social, if you're interested. 73's!! de VE7NGK
@Tom's Workshop hey Tom I would love to chat more with you over the air! Sorry for not seeing your reply earlier. I think I have a 100k resistor so I should be able to get the audio fixed on mine. I feel bad for buying this rig now that I know the product was a rip off. It is an amazing product for sure!
Hi Tom, I have a single 6w 420ohm resistor in that position so maybe they are trying to fix the issue. Keep up the videos. Now to start work on the usdx.
I bought one and it presents 1:5 swr to the radio on the input side. Any clues why? The store supplier gives no support. It is otherwise working on the output, and a good match to the antenna
Most interesting. I must confess that I've never looked at the SWR presented to my radio, with the exception of when I first got it. On 20m it showed 1.5:1. If you'd like I can take a look this evening when I'm home as to what it does on other bands. What bands are you getting that horrible match on?
@@rockshelter Wow, just wow. So, where to start. I've been running my amp on all these bands for months. And, like I said, I based my assumptions on SWR to Amp by just one test. Tonight I ran it through all the bands and this is what I got: 160 4:1 (I love playing here.) 80 7:1 (I had no idea) 60 5:1 (Never used it here) 40 6:1 (I use it here as relay for the western social net all the time!) 30 3:1 (Never used it here) 20 2.5:1 (I've had fun.) 17 1.9:1 15 1.5:1 12 2:1 10 2.1:1 (Had hoot last weekend.) So, um, I'd like to plead the 5th. I've never looked into this too much as both my RS-918 and the uSDX seem to not care, with many hours of transmitting done over the last 3 months to back that up. But your FT-817 will, as it has very fragile finals, So, I'd suggest not using it on 30 or lower. I'm going to think on this, as clearly the amp doesn't have any type of adjustable input stage, So, I'll see what might be possible to correct the SWR to the radio. But, honestly, I don't think there's much, other than a tuner between the radio and amp. Hope this helps in some way. 73's de VE7NGK
@@tomsworkshop5856 Thank you for taking the time and doing this thorough test. I wonder if these result applies to all of the units sold everywhere. I have read of at least one other user having his radios finals destroyed by using this amp. If there was a few more isolated test results elsewhere that roughly replicates our findings I would publish a warning about this product in every available platform or social media. I have no problem risking a little money on a cheap product that ends up being useless, but a product that could possibly destroy another expensive product by using it is another thing. Anyway, if there is an easy fix to get a better match to the radio I would like to try that. But really I would like my money back, but thats not likely to happen. Anybody in the market for a cheap amp should buy the mx-p50m. Its a little bit more expensive but so much better. Take care and thank you again. 73 de LB1HJ
I bought one of these for use with an USDX+. I cant get a good report from the pair. What settings on your USDX are needed to get this amp to work well with your transceiver? My signal reports are saying that I've got distortion when using the amp. Thanks in advance
Indeed, the uSDX+ (I have the white button one) Had multiple problems that all got worse when I used my amp with it. The best settings I found were Bias Min at 0, and Bias MAX between 75 and 90. The repairs I made to the radio included adding a capacitor to help with RF getting back into the radio via the mic's wiring, and installing a missing resistor "R23" that has a value of 100k. Not going to lie, the USDX radios all sound like Fisher-Price walkie talkies, so sound will never be as good as a commercially built radio. But I've gotten mine to the point that I've had several hours long conversations on it without being told that my audio is terrible. I hope that helps, and stay tuned, I'm working on my video of the uSDX+ v2 white button and hope to post it sometime this weekend.
@@tomsworkshop5856 Ok Tom, thanks for the good words. I'll start poking around in mine(which is also V2 version). My USDX works pretty good until I hook up the amp. Its good to know you got the kinks out. Thanks, Phil
I may be wrong but since it’s so sensitive to a bad match, I’m thinking you tune the antenna with an external tuner. Once the tuner is set, you have to put the tuner between the antenna and amplifier. Then the tuner can protect the amplifie. If you put it after the tuner and before the antenna, assuming a bad match, the amp isn’t protected. My question is, will it work on cw?
You are correct, the antenna tuner is after the amp, and you need to make sure the amp is de-powered before your tune up. (And make sure that your ATU doesn't decide to do an auto tune once your amp is on.) As far as CW, I would not recommend this amp for it. It doesn't have an external PTT-in, and it might not switch on fast enough if you're really good at code. hihi
