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On Sun, Sep 2, 2018 at 07:11 PM, Tech Guy wrote:

Changing the IF setup in software?

You only need to load the Raduino firmware for BitX40.

original sketch v1.01 with basic LSB functionality:

improved sketch v1.28 with many extra features:


73 Allard PE1NWL

Thanks for doing this. The diagram is very informative (need this diagram for the uBITx too). You are correct but a BPF (not LPF) after the mixer is probably better since the mixer is where most of the real nasty harmonics originate...

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All,

in preparing my talk to be held at the "UKW-Tagung" in Weinheim Germany next Saturday about my UBITX I prepared a level diagramme with some assumptions: the maximum powe rlevel at the input of a mixer is in the range of -1 dBm (near the 1 dB compression point?)

The result is intersting: als Allison already stated the gain of the TX stage after the first mixer is 48 dB under these assumptions. My guess is that "normally" a lower level (-10 dBm) will do better in respect of IMD resulting in nearly 60 dB of gain!

Another guess for the resultant spurs observed at higher output frequencies: the bidi amp (45 MHz) is not free of harmonics, i.e. also can and will produce harmonics! If true, these harmonics could be easily removed by introducing a low pass filter between the mixer ("45 MHz port") and the mixer itself. Who can and will try this mod?

Henning Weddig

DK5LV

Just couldn’t hide the beautiful electronics ?

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: D:DokumentWeinheim 2018BilderU_BITX_Block_original_TX_Pegel - Schematic.pdf

Uploaded By: Henning Weddig

Description:
estimated level diagramme for te TX section of the UBITX

You can access this file at the URL:
/g/BITX20/files/DK5LVs%20stuff/./D:DokumentWeinheim%202018BilderU_BITX_Block_original_TX_Pegel%20-%20Schematic.pdf

Cheers,
The Groups.io Team

I replaced the Arduino Nano and the SI clock chip and got the uBitx running. I then noticed a short on 2 data lines to the relays. I cleared the short, but after that the i2c bus always is sending data to the SI chip, and I usually get no clocks out, although sometimes I get one or two but not three. I don't think the i2c bus should have data on it unless something changes, ie the band or tuning after initialization. My question is what could keep it in this mode continually outputting data? I don't understand the code well enough to figure this out. I see two locations on ubitx_si5351 that cause data to be sent, but I don't follow what initiates them. The tuning works, updating the display, which means the Arduino is running the main loop. I fear the Ardunio has again gone south, but I don't want to pull it out again unless i am sure.

Thanks,

Howard

You need to load the Bitx40 firmware, as Allison mentioned.
Only other issue is the uBitx has pins soldered in place so the Raduino can plug into the main board,
the Bitx40 uses a 5 pin wire harness at that connector.
See this thread:??/g/BITX20/message/58169

On Sat, Aug 25, 2018 at 04:41 AM, Bill Cromwell wrote:

Hello Fabian,If you trace the circuit from the antenna it will lead you through several relay contacts to an inductor to ground. That is a piece of wire that wraps around and around with or without a core. Your meter uses direct current to measure resistance and continuity. Direct current sees any inductor as a plain old piece of wire - a short. So it sees that inductor to ground as a dead short. At RF frequencies however, it is NOT a short. Most - maybe all - radios will have this:)

Ok thank you, too now i am know this and i'm verry happy to know everything new from HAM and Radio technics.

So you should continue looking elsewhere for the problem.Have you completed the "alignment" steps? If the oscillators are far off frequency the radio will not work very well if at all.

I tried to set the BFO in the menu by display and the IRF510 (RVF2 + RFV3) current to measure and adjust with a screwdriver, but I still needed help. And I would have to adjust the Raduino on the knob (P2) but I would also need some tips for that.

Do you have a more experienced ham there who can help you?

Not really.. But today, later he say, a Ham would help me to test a few transmissions from him to me and i should say when receive..

Fabian, we all have or had different 'starting' places. It is not reasonable to assert that a kit is not for a beginner! At one time if hams did not make their own radios from scratch (not even a kit) they had no radio at all. The uBitx is not really so much of a kit. Building your own gear from scratch or from a kit is 'learning by total immersion'. Sometimes that method can seem frustrating but eventually we all get where we want to be. Just relax and enjoy the 'journey'. After you have finally sorted out the trouble and corrected it you will find it more satisfying than that Kenwood or Yaesu:) Those have their own rewards and can be an appropriate starting place for somebody else.I started out building radios from a pile of old junk harvested from dead radios. At times it was discouraging but in the end it doesn't seem to have hurt me:)

Sorry i unterstand and this is real you say. I didn't mean to say it was bad. I even collect a lot of bulky waste myself, such as radios and other electrical appliances and then solder them together and really like to make things. And doesn't want to be a "plug socket - amateur". So I have something to apologize for with the wrong wording.

And now about your English. Your English is very usable for a non native English user. I know only a few German words and not very much about the grammar or syntax. If I was suddenly transplanted to Germany I would experience 'total immersion' and would soon be speaking, reading, and writing German. It would sometimes seem frustrating but eventually I would fit right in :) For now your English is substantially better than my German.73,Bill KU8H

ok Thank you!


This was the text i have wrote for you..

Now are the question are:

-what i can do for better receive?
-what i should adjust at the points on the board: RVF2 + RVF3 and the other varable resistor near there?
-what software you think is the best for good receive, i would think of installing now the cec1.08?

ok this are my question at the momment..


thank you for helping me !

hope for answer, thanks

best regards Fabian, DO6FAB

Tech Guy,
>>>>Has anyone used a ubitx radino with a bitx 40? I ordered a bitx 40 before it came with a dds. Changing the IF setup in software? <<<<

I'm using mine for something different that Bitx40 though same idea, an Atlas210.

You have to alter the code, I'm sure you know that.

If you make OSC-0 and OSC1 both zero (0L) that shuts them off as you
only need osc 3 to replace the VFO?unless you replacing the crystal osc
and really why do that if it works.

The code has OSC2 as the tunable osc so change the 45mhz offset to match the
IF your using.? ?So its likely to tune around 5mhz (for the VFO version). IF you go?
IF+VFO then you at 17mhz and likely reverse sideband (handy if you want that ability).

Handling of CW and cal functions are kinda spacey as it was all assuming dual
conversion.? ?It this point I'd suggest seeing if there is a raduino code base
for Bix40 as the assumptions are closer to the needs and less effort.

IF done right you can do things with the raduino that were difficult with the VFO.
Things like split, RIT, A&B vfo, Reverse sideband (normal is lower) are some
of the tricks that can be added over an analog VFO.

Allison

Swap the sideband frequency settings or go into the code and swap the messages.

Allison

On Sat, Sep 1, 2018 at 08:49 PM, jim wrote:

consider ..Ft of 2n3904 is about 250 Mhz ...If beta rolls off at 6db/octave, then =at 250 Mhz, beta = 1..125 Mhz beta 6db better? (3db doubles =beta 2, 3db doubles beta 4)..60 Mhz 12 db better (4 doubles? 2,4,8,16)...30 Mhz 18 db better .(6 doubles 2,4,8,16,32,64)..

I finally found your text. You are writing inside the quoted section and the web version only shows a blue rectangle with three dots...??on an other wise blank page.? Be careful of the Emailer as its likely burying your answer as a the other guys quote.

Your supposition is however wrong.? For common emitter resistive feedback that is untrue.? The gain falloff is 6db octave
starting at some low frequency so by time you at 30mhz you have gone through a few octaves (3+ for 3-30 or -20db)
you are well down. Add feedback and you are way down as it does not decrease with frequency (in the ubitx case).
It is possible to have a feedback that decreases with frequency but you still run out down the gain.? Where does the
bend in the curve start?? Usually less that 3mhz and its downhill from there.? Also with wideband amsp the C-B feed
back capacitance and other parameters are not in that and they tend to be input and output impedance sensitive
as well as operating current influenced.

The usual calc for resisitive feedback the first parameter is?FT/F=? for 3904 its about 300mhz/30 or a beta of 10.? With
that try to make a power amp stages of 18db, voltage gain maybe but not power.? Assume 50 ohm input and output,
but it doesn't happen even with 200 ohm output.??

That and the HFE as I've written many times before falls with increasing current over 10mA, its in the datasheet.? When
you combine that performance at even milliwatt power is a fail.? At 20Ma is on the down side and at 50mA its down
from the peak by 40%. That or unbounded optimism or a hot batch.? With no margin and a lot of luck how many out
of a thousand will perform well.

Reality is that the 3904s in enough units to be a valid confirm are not performing.? Dial in RF1 for 11W at 80M
the driver output is easily a half watt.? By 30mhz you are down 11db to maybe 45mw.? Where'd the gain go?

Same for the 45mhz amp.? In isolation at 10mhz its 18.9 db, at 45mhz its 13db for 50 ohm in and out as that is
what the filter matching network expects and the mixers.? Also around 15mhz the IF amp is showing noticeable
and increasing phase shift when that hits a high enough number instability is seen save for the projected path
is not enough gain at that point..? Now we add the darlington pair effects sine they are running at .99999 (alpha)
their voltage gain is essentailly one but power gain is the result of high input impedance (limited to the prior stage)
and output impedance or about 4 (6db) so the IF amp has an apparent gain even with the poor showing of the?
3904 of some gain just due to the output power gain of the compounded emitter follower.

Yes you can get 3904 to oscillate at 450mhz too.? Doesn't mean anything as not all do.? But then I got a uV201
to oscillate at UHF once.
?
Allison

It becomes a big deal when they hook up a uBitx to their KW linear.
Especially if they goose up the mike gain to get enough drive.

My primary concern is that any future version of the uBitx meet regs for most jurisdictions.?
Worth keeping these issues visible in the forum till that happens.

Jerry

On 9/2/18 6:07 AM, MadRadioModder wrote:

... the guy who may have just received his license and bought a uBITx thinking it was a nice cheap way to enter the world of HF that now has to deal with this (like some friends of mine).? They can either rely on the experts (self-proclaimed or otherwise) to bail them out of this mess or be given a very simple solution that is possible for them to execute. ?...

Or they can ignore it all and just use the damned thing. I suspect that's what most users will do. I'd guess that the vast majority of uBitX buyers aren't even aware of the issues and those who are don't care. And, realistically, it probably isn't that big of a deal anyway (which I realize is heresy to many on this forum but is nonetheless the reality of the situation).

My $0.02 worth...as always, YMMV...

Mark AA7TA