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I simply disagree.?

Hi,

So I can test my uBITX for harmonics and such, I built a "QRP+" dummy load, this weekend, with a 46 DBm attenuator on board. By mounting this to a bigger heatsink or adding fans this should be able to handle more than QRP levels of power.

The board has two 46 DBm outputs, one to a SMA connector and another to a pin row connector. In situations where I don't care about a standard 50 ohm attenuator output impedance I supply the 1 ohm (40 DBm) output to the pin connector.

The next pin up will be RF voltage, from a divide by four voltage divider feeding a 1N4148 and a bypass/filter cap to read the peak RF voltage. The uBITX is reason I'm setting up an RF workbench/lab again (and having great fun doing so). Oddly enough I don't have any 4148s in my parts box, so am ordering some before I add the RF voltage output. It will be interesting to see how flat this thing is across the HF frequencies.

I built this on a 0.025 inch thick copper sheet, and even with a 140 watt soldering gun it was a challenge to get copper hot enough to melt solder.

I laid out the main parts in KiCad, printed it out on paper and used a center punch to mark the position of the parts mounted to the copper sheet and the mounting holes. That was a refinement over the good-old-days. Really beat the old time way of tediously measuring and scratching lines on the copper.?



Tom, wb6b

Gordon

My characterization of the uBitx as "garbage" is a term of art, not science. However, when a commercial radio is advertised as "Build the ?BITX transceiver in an evening. A general coverage, 10 watts HF SSB/CW transceiver kit? with features you NEED for operating ease, convenience and versatility. It works from 3 MHz to 30 MHz, with up to 10 watts on SSB and CW, with a very sensitive receiver." it would be reasonable for operators like Joe to assume they would have a compliant radio on the air after an evening's work. This is simply untrue.

"The front-end diode mixer followed by a Hayward/Kopski TIA makes this a crisp receiver that doesn’t overload easily." Simply untrue. Using this receiver 3 miles away from a 1450 KHz AM broadcast transmitter is impossible through 20 meters due to overload. No other radio I own, including homebrew SDRs has this issue.

"10 watts of low distortion SSB provides you with enough juice to have thousands of contacts on all HF bands." Again, simply untrue. Unacceptable levels of SSB distortion begin at less than 2 watts and result in adjacent channel splatter at any level above that.

I am not bashing. As a basis for experimentation and improvement the uBitx is a treasure. As the basis for a rig to be connected up in one evening and put on the air, it is indeed "garbage".

WA8TOD

Joe, Warren published some pretty good numbers way back, and Allyson probably did also, and basically CW mode was in trouble on all the bands. Single side band not quite so much as long as you didn’t scream into the mic, or use bands higher than 14 MHz. (but still pretty close to in trouble or beyond it many places) It highly depended on how the unit was set up. Ashar Farhan indicated that units properly adjusted were compliant. Others disagreed based on measuring several production units. You, like I, would have to go back and find all their particular posts with their data, to jfind the exact claims. None of this has been adjudicated in any official proceeding.

Harmonics are a problem for most of the bands, where is spurs are an additional problem above the 20 meter band.

It seemed to me that CW was in much more trouble with harmonics, than single side band. I along with several others have introduced ways to reduce the bleed through via the relays around the excellent filters at the end of the power amplifier design. My solution seems to work, and I think others have also shown their solution works (even for the CW problem) on 20 meters & below; individual band pass filters or other solutions would be needed to fix the spur problem beyond the 20 meter band; fixes to the low pass filter do not repair that particular problem.


So I think that people who are concerned about this are going to do some sort of a filter or relay fix on the power amplifier, or replace it all together, and operate on the 20 meter and lower bands. My fix had a total cost in the range of $15 or less and an hours worth of work.

A lot of other people aren’t going to care and will use the unit as it already exists, and because it is so low powered this isnt going to cause that much trouble. It would be a different issue if they all bought high gain external amplifiers and magnified the spurs & harmonics many many times.... that would eventually get noticed


I hope that helps you. Because several people here did such a great detective work figuring out exactly what was the problem with the harmonics, fixing THAT became a rather simple affair.

I’m going to see what the postage cost would be to send out the simple external relay board that I came up with. The board itself only cost $2.50 even after DHL shipping from China. I think it can be mailed out as simple first class mail just with a “non-machinable surcharge” of $.25 or so.

The first radio I had, had severe problems, didn’t work at all, and took me months to make it work. After that it was a joy and I used to make many many contacts. Heathkit HW 16. By comparison, the uBitx is a joy! Much of life is how you look at it. Nothing is perfect, but to disparage items that do have known flaws as complete garbage, I think is an attitude that does not benefit the holder much at all. Take that as some free psychological advice.

Cheers

Gordon

Hi Joe

Your question illustrates the reason for my stone soup admonition.

There is no valid answer to your question without additional parameters being set that require precise measurement and monitoring. The table you ask for will be very different depending upon the power level used, the loudness of your voice and the resulting drive level on SSB, the voltage level applied to the PA, etc. The table constructed assuming a power level of 5 watts will be very different for one assuming 1.5 watts or, God forbid, 15 watts.

For those who want to experiment, find problems, devise solutions, and who are willing to defer air operations until they have ascertained their uBitx is compliant, it is a wonderful source of learning and fun in the true spirit of amateur radio. For those looking for a radio to simply package and put on the air as it stands, the uBitx is the antithesis of what ham radio should be.

There is plenty of room and their are plenty of options in our hobby for those who wish to simply operate, gather awards, rag chew, and contest. There are also many options for those who wish to build and experiment to hone their skills and to have a sense of pride and accomplishment for what they have built. The uBitx is ideal for the latter and a nightmare for the former. Neither group of amateurs, the appliance operator or the builder, are better or worse than the other and neither has the inside track on the hobby. But both need to understand what valid equipment choices are available to them.

WA8TOD

Hi,
My regards to the chef, on the Stone soup. :-)
I have no fancy test equipment, but I have
a working uBitx v4 board.

I've read thru all the links and emails on the current problems
with the Ubitx's spurious emissions, but can't seem to get
a clear picture of what bands and modes are legal for
transmitting in the US. The sheer number of posts
and technical data is a bit overwhelming.

Could one of you experts, make a simple text table showing
which bands and modes are acceptable on a stock board?
Something like:
This is a fake table for example.
########################
80m no cw, no ssb, no digital modes
60m digital fine
40m no cw, ssb, digital fine
30m digital fine
20m cw , ssb, digital
17m etc
15m etc
12m etc
10m etc
##########################

Thank you,
Joe, KN4OND

I heavily modified the uBITX code to work with an Arduino and QRP Labs si5351 board, which was the easy part: The hard part was ripping out all the extra IF stuff and calibration! I'm not cut out for that part, but I figured it out with some help. The only reason I did that was because I wanted the easy USB/LSB switching but also wanted a rotary encoder. It works, but is clunky. using Allards code is a great idea :-)?

You can also use the QRP Labs VFO kit, and just invert the IF offset to get USB. Remove caps C91 and C92 to do that.?
--
Ryan Flowers - W7RLF

Perfect. I indeed had it connected the wrong way. Due to my case, I had to flip the connector to the other side of the raduino board. And that means the pinout is mirrored. Works now. Thanks!

On Tue, Sep 4, 2018 at 01:04 PM, ajparent1/KB1GMX wrote:

Most cases its worth more
than the price of it.? Education is usually far more costly and not near
as much fun.?

Hi all, This to me is the mos important. I have learnt SO much in the last 12 months from the uBitx. More than my FT-450D could ever have thought me.
You know, and I'll make a board the fits on top of the ubitx to help alleviate the bugs, so those less inclined to experiment can enjoy the benefits of the whole community contributing and working together, again, at cost price. Why because thats what I believe the ham spirit is all about.

I might call it the uBitx Anti-Stone Soup add-on board. ;-P

I'm also working on a way to measure spur and harmonics using an RTL-SDR, might work, might not, point is, I'm trying and learning.

What have you done today to progress the hobby?

73 and happy hacking.
Nick VK4PP

I' had the same. After frequency correction made BFO, after this steps the side bands has come to the right position: LSB on 40ty and USB on 20ty My correction for frequency: 18, BFO-11996380.
George

uBitx v3 board. I can't get the LCD display working. I've tried two different 1602 modules with the same result. (The second one, white-on-blue, shown below).

It's lighting up. Top row blank, bottom row all squares. Twiddling the blue trimmer pot on the raduino board has no effect whatsoever.

At *just* the right viewing angle, I've been able to make out the text "???????? = 000 " on the bottom row. The = represents 4 parallel lines, though. Turning the main VFO dial doesn't change the numbers, but clicking it makes the whole display blank out for a second.

Operator error, bad wire-up, defective Raduino, or something else? Thanks! -m

Ok thanks, if I get I'll try to use. Allso good BFS17.
George UR4CRG/RX3ARG

On 9/3/18 6:42 PM, Kees T wrote:

...
If "in the old days", enough people had access to Rigol DSA815-TG (Spectrum Analyzer and Tracking Generator) test equipment, NONE of us would have successfully built anything to get on the air and we'd all be "appliance operators".
...

We probably shouldn't feed the trolls, but...

I agree. I remember the 60's and 70's gear (I was first licensed in 1961 as a Novice). I'm sure those WWII surplus ARC-5 transmitters weren't very clean (I had one). All those T-60's (still have mine), DX-20's, etc, not to mention all the homebrew rigs built with scrapped TV parts on pine boards, weren't very clean either. I remember all the chirpy drifty stuff on the air (some of it relatively expensive commercial gear). I can't imagine that a bunch of uBitXs can be any worse. HF is probably more screwed up by the millions of non-compliant electronic devices we all have...CFLs, LEDs, multi-speed furnace blowers, leaky power lines, etc...than by all the ham gear put together.

That's not say we shouldn't try to be strictly legal but you gotta be realistic about it (FWIW, I have a set of QRP Labs LFPs that I'm planning to graft into the uBitX).

The uBitX got me back on the air...I've been on more since I got it than in the two years, not to mention starting to build stuff again. It's probably the most radio fun I've had since I built my last Heathkit. I've learned a lot from the folks on this forum, too.

Anyway, my $0.02 worth. As always, YMMV...

Mark AA7TA (WN9CJE in 1961)

My position is its got bugs.? So what.

Fix the worst ones.? The low pass filter issue has several fixes.??

Spurs if you stay under 20mhz they are generally not a big deal.
So you didn't get 10M big deal, if you need it add a band pass filter
where the current 9 element low pass filter is. But you loose the
low bands if you don't figure out switching.? Figure it out ask questions.

Some of the other bugs are minor compared to those.

Bottom line its not a FT817, never will be.? Most cases its worth more
than the price of it.? Education is usually far more costly and not near
as much fun.? If you became a ham to learn more about electronics
and radio here you are.? Learn as you don't need my permission.

Allison

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I had a problem long time back with K1 not operating correctly. Some others have had this problem too. Took the cover off, might be interesting to see construction.

Its hard to see in the pictures but one contact was restricted in movement by the adjustment of the other NO contact.