Re: stone soup ingredient list, what bands and modes are usable

Gordon Gibby <ggibby@...>
 

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

On Sep 4, 2018, at 04:57, Joe Milosch <zzmiloschxx@...> wrote:

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



Join BITX20@groups.io to automatically receive all group messages.