Date   
Re: RFI from uBitx TX after AGC and other mods installed

alans77@...
 

Hi Don: When I unplug the AGC board with the audio and +5 volts still attached the feedback remains the same. When I separated the +5V and ground twisted pair and disconnected the ground feedback remained the same. When I removed the +5 volts from the board the feedback disappeared even with the board plugged in. Moving the pop fix board toward the front panel made no difference - feedback remained with +5V connected. The dangling wire near R106 is the D7 purple wire for the S meter it was not connected and I taped it to the front panel for these tests.

73,
Alan

Re: Easy, Inexpensive Cooling Fan, Excelway Case

Dennis Yancey <bigbluedry@...>
 

What size beads? And where did you get them? How should they be installed?

Re: RFI from uBitx TX after AGC and other mods installed

alans77@...
 

Pat: That is a great idea!
73
Alan

Re: #ubitx safely putting on tight tuning knob #ubitx

PeteWK8S
 

Ambitious. Good luck with the development. I'll be watching with great interest. Thanks for sharing.

Pete WK8S

Re: Latest Build, Mods and results.

alans77@...
 

Hi mike, can you provide a schematic and parts list for power leveling relay fix?

73,
Alan

Re: RFI from uBitx TX after AGC and other mods installed

Don, ND6T
 

I agree. That would be an excellent fix, Pat. But it shouldn't be occurring. Alan, can you take voltage measurements of Q1? From ground to the base, and from ground to collector when transmitting? It seems that the RF is coming in on the 5 volt power, even though it is well bypassed. Lacking a 'scope, a pair of headphones with one side to ground and the other through a .1uF (or so) blocking capacitor will let you listen to the +5 volt supply. I mean putting the capacitor in series with the headphones. The audio amplifier is disconnected from the pre-amp (which is gated off by the "click" board anyway) and is bypassed to ground by C78 (not shown on the schematic). Which brings up a point: Does the volume control affect it at all? Taking the input to U1 to ground by turning the volume all the way down should eliminate it, I would think. Unless it is coming in on the +12 volt supply (which has nothing to do with the AGC).  -Don

Re: Latest Build, Mods and results.

M Garza <mgarza896@...>
 

Alan,
I think this is what you are looking for.

Marco - KG5PRT

On Thu, Jun 28, 2018 at 2:20 PM alans77 via Groups.Io <alans77=yahoo.com@groups.io> wrote:
Hi mike, can you provide a schematic and parts list for power leveling relay fix?

73,
Alan

Re: Latest Build, Mods and results.

M Garza <mgarza896@...>
 

And that was the wrong link...

Sorry

Here is what the link should be:

Marco - KG5PRT


On Thu, Jun 28, 2018 at 2:36 PM M Garza <mgarza896@...> wrote:
Alan,
I think this is what you are looking for.

Marco - KG5PRT

On Thu, Jun 28, 2018 at 2:20 PM alans77 via Groups.Io <alans77=yahoo.com@groups.io> wrote:
Hi mike, can you provide a schematic and parts list for power leveling relay fix?

73,
Alan

Re: Finished building my uBitX!

Gwen Patton
 

When in use, those rectangles clear up nicely. It's a matter of viewing angle. The pictures were from too straight on to see the display clearly.

Shipping issues

AC0AX
 

Not to beat a dead horse but are there any shipping issues. Last I read was that the backlog was gone. I placed my order last week and have yet to receive a notice that my ubitx has shipped.

Thanks
Hal AC0AX

Re: RF power chain mods and improvements..

Sascha Bohnet | DL5SMB
 

Thank you Allison for the clarification. I read the thread about the mixing problem and understand where the problem is.
Maybe I will try to play around with bandpass filters, but this is no priority - output is not everything, I would rather have a clean signal.

By the way, I checked with my calibration station - and the RX seemed to be okay  as soon as I fed a not changing/fading-signal.
Maybe it is / was a problem related to the AGC or a combination of both.

I've just another small question which I hope you will not crucify me for:

Is it possible that changing R23 is abolutly necessary, if Q20 is swapped to a BFR106?

I had not checked the transmitter with modulation yesterday as I only tested CW which was good. Today i connected a microsphone and noticed
that here was nearly no output at all with SSB modulation anymore. So I also changed R27 to 39 ohm but that did not doing anything at all.
R23 I thought would not be really important as it was only changed from 10 to 18 Ohm (okay, in percentage it is a lot) and i thought it would be pointless.

So I changed all BFR106s back to 3904s. Q20 was the transistor which I swapped last - and as soon as that one was in again modulation went up again.
So was this really an operating point problem? If not maybe my transistors are really of bad quality?

Re: Latest Build, Mods and results.

Mharpen@...
 

CIRCUITBOARD DETAILS.
Hello Alan. Thanks for your interest. Attached is a wiring diagram (more useful than another schematic), an underneath view of the circuit board which should help with your construction.
The relays are the same as used on the uBITX board i.e. HFD27-012-S available on eBAY. The pots are 100 ohm available on eBAY. The 100 ohm resistor functions as the "pot" for 10M since this has the lowest output and runs flat out. This is actually a very simple mod to do and work FANTASTICALLY. 
Mike N6CMY

Re: RFI from uBitx TX after AGC and other mods installed

Mark M
 

Don...

I finally had a chance to start looking into this on my ubitx (I'm seeing the same issue). I managed to borrow a scope and putting it on the 5v supply seems to indicate that you're right. I see up to about 40 mv p-t-p on the 5v line when xmitting SSB with the AGC board not connected at all. It's pretty clean in receive. I'm tapping into the 5v line on the raduino. So that certainly looks like the smoking gun.

Now to figure out how it's getting in there...

Hope this helps...

Mark AA7TA

On 6/28/18 12:30 PM, Don, ND6T via Groups.Io wrote:
... It seems that
the RF is coming in on the 5 volt power, even though it is well bypassed. Lacking a 'scope, a pair of headphones with one side to ground and the other through a .1uF (or so) blocking capacitor will let you listen to the +5 volt supply. ...

Re: RFI from uBitx TX after AGC and other mods installed

Don, ND6T
 

Sure does, Mark. Now to find where it's coming from. Please check the 12 volt input pin of the Raduino's 7805. See if it is there, too. On my AGC boards I don't have ANY bypassing on the 5 volt feed and still don't hear anything. But my 12 volt is well filtered. Could be the difference. -Don

Re: RF power chain mods and improvements..

ajparent1/KB1GMX <kb1gmx@...>
 

R23 change yes and 18 ohms may be too low still.

Likely operating point, R21 may be too low.

Before you go to band pass filters try one thing... pain to install, Low pass filter between the junction of
pins 5 and 3 on t2 (IF port of the first mixer) and R27 and c16 (the junction of the RX/TX 45mhz amps). 
The low pass filter is for 45mhz cut off I use .176uh (5turns on t30-6) and 68pf on each side (pi section).
This is the only thing that seems to help with the spur and enough to be ok if the drive is not excessive. 
If the TIA is getting excess out of band or distortion the spur is bigger the filter helps (about 3-6db). 
Sample size of one can't prove it.  Worth a try if you can measure the results before and after.  

Allison

Re: RF power chain mods and improvements..

ajparent1/KB1GMX <kb1gmx@...>
 

One last thing, testing CW uses none of the IF and modulator so if it works you can't know if the IF is fine.

MUST test using SSB.  Ideal bias for Q20 will have the collector at about 6V (+-1V).  To high or low
and it functions poorly.   In mine the 3904s had it at 3.5V, that is too low.  This is typical of normal
variations across different device lots devices.  

Allison

Re: RFI from uBitx TX after AGC and other mods installed

Mark M
 

After I sent this it dawned on me to check the 12v supply as well. Sure enough, it's there too. FWIW, I'm powering it off a 20A Astron 13.8v linear power supply and feeding it into my old Heathkit Cantenna dummy load.

I have it installed in one of the amateurradiokits.in cases. The power wiring runs very close to the antenna connection and the final amp transistors. I tried twisting the wires tightly but it didn't make any difference.

If I disconnect the final amp supply line it goes away and there's no noise from the speaker with the AGC board in place.

Anyway, a couple more observations...

Mark AA7TA

On 6/28/18 5:07 PM, Mark M wrote:
Don...
I finally had a chance to start looking into this on my ubitx (I'm seeing the same issue). I managed to borrow a scope and putting it on the 5v supply seems to indicate that you're right. I see up to about 40 mv p-t-p on the 5v line when xmitting SSB with the AGC board not connected at all. It's pretty clean in receive. I'm tapping into the 5v line on the raduino. So that certainly looks like the smoking gun.
Now to figure out how it's getting in there...
Hope this helps...
Mark     AA7TA

Re: Finished building my uBitX!

Don Stewart
 

Compiler warnings

Jack, W8TEE
 

All:

Several people have asked about compiler warnings they are getting, like:

        warning: ISO C++ forbids converting a string constant to 'char*'

A variation on this are the "deprecated" warnings issued by the compiler. Even more confusing is the fact that the warnings they now see were not there before. Usually, this is because of a compiler update. As a general rule, compiler warnings do not prevent the compile from finishing or performing an upload. However, warnings mean something is bending the rules. For anyone who might be interested, this was my answer to one of those people.


Steve:

I think everyone understands what a syntax error is: Not following the rules of the language. Semantic errors are more difficult because the rules are followed, but the context is wrong. For example, we know an English sentence needs a noun and a verb...those are the rules. However, if I say: "The dog meowed.", it obeys the syntax rules, but the semantics are out of context. I'm not sure how far back, but around version 1.65 the GCC compiler started performing some syntax and semantic checking at the "lint" level. My company produced a C compiler back in the '80's and we had a "picky flag" that could be set from 0 to 10. It performed syntax and semantic checks at increasing stringent levels. I never saw any published C code that passed our Picky Level 10. Indeed, that level was so intrusive that we never used it. Most work was done at Picky Level 4. When we were ready for distribution, we cranked it up to level 10. Truth be told, we still didn't bother to fix some of the warnings. Somewhere between 1.65 and 1.85 they kicked the GCC compiler's equivalent of our Picky Flag up a notch, hence warnings now where none existed before. That's a good thing.

However, the bad thing is that there are now a lot of warnings that unnecessarily cause people concern. Even worse, a lot of it comes from libraries, which is NOT your responsibility to fix. The library writer should fix those. When I first compiled the µBITX code, I had probably a hundred such warnings, mainly because I insisted on using only one INO file, making all the other CPP files (plus a header). True, it was a pain in the butt to fix all the warnings, but it was worth it. Why? First, by not using multiple INO files, the compiler cannot perform data type checking. You'd be surprised by how many bugs hide under the blanket of missing type checking. Second, because the compiler no longer has to glom all the source files into one huge file to compile it, it allows the GCC to perform incremental compiles. This is a HUGE win. When I compile the JackAl code for the first time in the morning, it must recompile all files. In the process, it clears the "dirty flag" for each source file. Even with my 8-core, 3.7GHz machine with a mega-munch of memory, the JackAl code takes almost 2 minutes to compile. If I used all INO files, it would always take 2 minutes to compile the source code regardless of how many file changes I made. With incremental compiles, it sets the dirty flag and recompiles only those files that have changed since the last compile. This drops my compile time (on a single-file change) to about 5 seconds. Given that I might do 30-50 compiles a day, you do the math

Kind of a long answer, but it's important that you understand what's going on "under the hood" from time-to-time. Usually, compiler warnings can be ignored, but always keep in mind it still means the compiler saw something it didn't like.

Jack, W8TEE

On Thursday, June 28, 2018, 7:13:32 PM EDT, Steve Smith <steve@...> wrote:


thanks - I erased the EPROM and then calibrated and I am getting real results. These were new part so I am not sure how the EPROM would have had values, but the first few times we loaded the software we did not have an SD card in. Could that have affected it?

Also, thanks for the explanation of the warnings, Jack. I am running version 1.85 of the Arduino IDE on Windows 10. Is there a reason some folks get the warnings and others don't? Is it a setting in the IDE?

73s

Steve

Known issues on uBITX r4 #ubitx

hirosmb@...
 

Hi, all.

I’m really new to uBITX and planning to place my order to hfsignals.com very soon.

Then please share its known hardware issues of uBITX r4 that I need to modify or solder.

Thanks in advance and hope to QSO with my uBITX soon.

// hiro, JJ1FXF