Re: Dynamic mic on ubitx

MVS Sarma

Dynamic Mics are Great for music and performance.
 After all for speech communications limited to just 1.5  to 2.8KHz bandwidth, perhaps  any mic would suffice.

we don't get FM quality or DRM (digital radio Mondial)  from a HF rig.


Re: Amplifier chain design - best practices

Howard Fidel

I've been sitting here on the sidelines for a while. I was hoping to have a complete solution finished by now. However, life gets in the way. I unexpectedly got 2 consulting jobs, plus my teaching job has eaten up most of my free time. However, I think it is worth putting  my 2 cents in now.

I will address the harmonics issue. We need to look at the root cause of the problem. The harmonics occurs in CW because it is direct conversion (or no conversion?) CLK 2 runs at the operating frequency. This clock comes from the infamous SI5351 chip that is also causing the spurs. Well, this clock is a square wave. The mixer it drives is unbalanced in CW and the clock just passes through and goes through a lowpass filter. (L1-L4 etc.) This removes frequencies above the 10 meter band. As most of you know, a square wave is made up of only odd harmonics, so we have the 1st, 3rd, 5 th etc. harmonics coming out. So for the 80 meter band operation many harmonics will pass through this lowpass filter get amplified and need to be filtered out by the output lowpass filter. We see fewer harmonics from 40 meters, mainly the 3rd since the others are removed by the first lowpass filter. At 20 meters and above the signal coming out of this filter looks like a sine wave, it has all the harmonics removed, hence there are no harmonics coming out of the transmitter. Garbage in garbage out. There are many ways to solve this problem. To date most everyone has blamed the poor output filters. We could also fix this problem by insuring we always drive the transmitter section with a sine wave to begin with.

So, we could modify the L1-L4 so that its cuttoff frequency is about 8 MHz for use on the 80 and 40 meter bands and stays what it is for the other bands. This will remove the harmonics earlier in the chain.

 Another, easier  way is to heterodyne in CW as well and go through the 45 MHz filter. So we need to move the unbalance circuit from the above mentioned mixer to the CLK1 mixer. Drive this mixer at 45 MHz and clk2 would would be the same frequency as we use for SSB and the harmonics would be gone. To do this all we need to do is lift R105 and so it stands up on the C1 side pad and place a jumper wire from the open end of the resistor to pin 6 of T4. Of course the software needs to be updated, but now without any filter changes, and with a very simple hardware change the harmonics are history!


Re: Newbie Help



I am thinking the stock firmware is not a significant factor in CW operating.  I would suggest using a CW audio filter with the uBITX.  One candidate is the hypermite from 4stateQRP - there is at least one you tube video demonstrating its usefulness in the uBITX.  I understand there are at least 2 different widely used alternatives, but I suggest using the uBITX as is to discover factors you think need improving to find the best fit.  Enjoy your rig. 


Re: JackAl System Preview

Mark Kesner

If those issues were solved, I'm sorry I missed it.  I've seen others with the same issues.  In any case I'm glad you are going to give it a real shakedown on CW.  Please report the results of your tests.  Looking forward to trying this out. 


Re: Amplifier chain design - best practices


On Fri, Sep 21, 2018 at 02:58 PM, Jeff Omundson wrote:
It is a little hard that parts become obsolete and so the projects might be difficult to build as is. 

I have booth books and more even old copies of HamRadio, 73, CQ, Pop'tronics.  Its rare I
find a circuit that can't be built because the device usually a transistor or tube is unobtainium.
As a experimenter that's part of the game to figure out what part that is available might be
a good match.  For the most parts Diodes are easy, most transistors are not magic either.
I still pull down SSD and play with ideas.  Spice, rarely and I've driven that and many others,
then again I can drive sim or a slide rule its just numbers and if you don't understand what
their significance its data not information.

The rest of the parts are coils, caps, and resistors and they are fare from rare.  There may
be exceptions but they are far from the rule.  

True thing that ubitx would take people into parts of tech they would never have gone.
Playing with the user interface (raduino firmware) has been the big fun for me.  I was
shocked how few understand superhet radio being a near 90 years old and well
understood.  I suspect that from it being new to people that have never worked with it.
So they get to learn it and all the little things that go with it.


Newbie Help

ed ridolfi

i have a uBitx that I want to use primarily for SOTA using a straight key and the stock 2-line display. Of all of the firmware options, which one should I install for 2-line display and straight key cw?

tu dit-dit

Re: Amplifier chain design - best practices


thats my take on the uBitx ...Simple ie cheap parts ..Easy to work on ..Its all right on top ..spread out with BIG surface mount parts ... Play to your hearts content


On Friday, September 21, 2018, 12:21:03 PM PDT, Curt via Groups.Io <wb8yyy@...> wrote:

I was only citing K2 as example, yes now unobtainable or costly parts as I alluded to. Some of its circuits, like the uBITX, have legacy to discussion in those 2 W7ZOI et al books. The older one has lots of interesting concepts, but many unobtainium parts. What we can get cheap enough can change rather quickly.

I respect many folk around the world cannot afford a K2, hence the uBITX paradigm. Lets see how that new QSX related IRF510 PA works when it comes out.

73 curt

Re: Ubitx - using AGC #ubitx

Richie Chambless

I’ve taken a look at this circuit, too. I think Sunil is talking about the power to the first bi-directional amplifier (receive +) before the mixer. I don’t know how well that would work, but I guess it could be worth a try. I’ve added a manual RF gain control to my Bitx using Fig. 6.42 from EMRFD. It could be connected to something like that and probably work.

Re: Amplifier chain design - best practices

Jeff Omundson

Thank you for the thoughtful responses!  Great ideas to digest.  I have the Solid State Design book but have not worked my way through it.  May be that is homework :-)  The explanation at the start for biasing transistors always made more sense to me than what I read in other books, including EMRD.  It is a little hard that parts become obsolete and so the projects might be difficult to build as is.  I suppose it could be broken down into smaller bits and then modelled in SPICE with best guesses at replacements for hard to find bits.

I thought buying the uBitx would be kind of a simple and unchallenging project radio.  I bet a lot of people didn't expect it to take us where it has!I haven't done any of the work to make it better, but I appreciate all the work that is being done.  It has prompted me to think deeper about multi band transceivers and it has been interesting to observe the community (and certain individuals in particular) work out solutions.  I think we are all learning more than if we were content to just play radio on the major commercial offerings.

Thank you to Ashar and all of you who have spent so much time working on this and sharing the knowledge!


Re: Ubitx - using AGC #ubitx

Jon Titus, KZ1G <tituskz1g@...>

I find clarity and precision of instructions--if any--sadly lacking from many electronic kits and projects.  The same goes for illustrations that lack important details such as part locations, pinouts, part numbers, flow charts, etc.  Some of our good ham writers and editors might offer to help, but it's an uphill battle.

Jon Titus, KZ1G
Herriman, UT USA

Re: V3 uBitx Very Shrill Audio

Curt M.

Hi everyone. I’m up and running and the radio sounds good!

I went in and did a Set Calibration and then Set BFO and all is good. Boy you can really get this thing out of whack if you’re not careful!

I’ve already had my first QSO between my home QTH near Pittsburgh, PA and Winfield, MO, which is nearly 600 miles. The guy was running a net and said that he was impressed that I could make it that far today on nearly QRP power. 

Thanks for for your help. 


Re: Nextion Basic 3.2 Display will not update #ubitx

Kai Nilakari

Anyone of you having TFT file for 3.2 inch basic display?
The one which is in a zip package is too small, loads ok but looks strange in the upper right corner...and my fingers are way too
thick to press those small buttons. The previous one looks good.



Kai Nilakari

Couldn't get it even in as the display says it is not for this 3.2 standard.

How can this be so damn difficult?...



Kai Nilakari

Hi guys,

can't see any NOT ENHANCED tft file for 3.2 in screen which I use in my radio.
Tried 32E_F_0_2d.tft but no go...

Or do I just miss something?


Re: Amplifier chain design - best practices


I was only citing K2 as example, yes now unobtainable or costly parts as I alluded to. Some of its circuits, like the uBITX, have legacy to discussion in those 2 W7ZOI et al books. The older one has lots of interesting concepts, but many unobtainium parts. What we can get cheap enough can change rather quickly.

I respect many folk around the world cannot afford a K2, hence the uBITX paradigm. Lets see how that new QSX related IRF510 PA works when it comes out.

73 curt

New from the W0EB/W2CTX/N5IB "TSW" gang #ubitx

Jim Sheldon

I just got done posting a couple of medium resolution videos of our 2.8" color display (touch screen) but with a "non-touch" feature, control by wired or wireless MOUSE.

The videos are not professionally done and were made using my Samsung phone's camera.  I had to really compress them (the on-camera raw videos were over 1 gigabyte each) so the screen resolution isn't the best but it is readable and does show the capabilities of using a mouse for control.

This display comes with a small plastic stylus which can be used for "Touch" control and I'll post a video or two later demonstrating the stylus for touch control of the uBITX.  On the small display though, the mouse is really easy to use and is actually my personal preference for controlling the rig.  With the mouse (or our optional wired/wireless keyboard) there is no need at all to touch the screen and also no need to use the encoder or function button to control the rig.  They still work though, we haven't eliminated them altogether.

The videos are posted on the TSW website, in the files section.  They are contained in a directory labeled Experimental Videos and are accessible to all.  We hope they are informative and that you get usable information on our display operation from watching them.

Jim Sheldon, W0EB
for the TSW team

Re: Amplifier chain design - best practices


I also too have the K2 manual for my unit ...Looking a "little further in front" you will notice 5 ea. band-pass filters ...Not dc to daylight transmit path ... if you want K2 performance, buy a K2 @ $800 to $1200 ...(glad I got mine when they were cheap)
elsewise work with whacha got


On Friday, September 21, 2018, 10:15:31 AM PDT, Curt via Groups.Io <wb8yyy@...> wrote:


great question on what's a good transmit path design.  since I have the K2 manual here --

predriver is a 2n5109, feeding a (;3 transformer on a FT37-43

driver is a 2SC2166 NPN feeding a 12:8 transfomer on a FT37-43

maybe some soft equalization network here ?  that's all I see that might seek to flatten RF performance

the PA is push-pull pair of 2SC2166 into a transformer to achieve the desired output power to feed 50 ohms

these devices fit the original K2 price target but not now the primary, global uBITX users.

the FT817 uses different PA devices for VHF/UHF than HF I think.  I imagine the VHF/UHF PA module may cost more than a uBITX.  obviously the climb for HF to 50 MHz requires more savvy PA devices. 

on the uBITX PA, when details are revealed on the IRF510 PA designed by Allison and Hans for the QSX there will be something of value here for v5, and to see if we can improve use of the v4 board. 

73 Curt

Re: I find This Shorted Circuit on Raduino, here the pics..plz Help? #ubitx-help

sdr freak

Hello again to all HAM,

I should ask again because the Ubitx doesn't receive like it should, till till today..nothing has found but this should not right when see the Ubitx v3 (FCI) first batch first shematic from ubitx constructor Farhan and when look the pin in this doesn't contact toghether...

Please help me again the issue from bad receive like not able to hear ssb stations right and one other pointmi found, no AM stations can be hearable right only bad stuff that shows an idea of an AM radio station and this can not be...

Please help he

Re: Amplifier chain design - best practices


 Spice it ...I did (using QUCS) .... Nearly a direct short to ground off the high impedance point of the amp (before the change) ...and you still have a linear control of the following amp chain (just checked it on my bench ...100 mV p/p in at head of LPF where it comes from the mixer to top of RV1 (3.0 V p-p) ...~30 db gain on modified Q90 circuit


On Friday, September 21, 2018, 10:25:26 AM PDT, ajparent1/KB1GMX <kb1gmx@...> wrote:


Replacing RV1 with a 10K is not good as it would put all the adjustment in the last 5 degrees of rotation.
A 500 ohm may be better.

But you begging 1 db of gain increase for what reason?   Replace the 3904 in that stage prior and the
performance jumps a greater degree and fixes the actual problem there.


Re: Startied using uBit-x-Happy-Happy

Joe Puma

Andy I just ordered a 3.2 screen. I’m excited. Can’t wait to get it. This radio has been a fun build so far despite any technical imperfections. 


On Sep 21, 2018, at 10:16 AM, KM4TRT via Groups.Io <garello@...> wrote:

Hi Dave, yes I am excited about the touch screen.- Its called a NEXTION
Dr. Ian has several websites on how to wire up,

Here is where I bought on ebay.  I paid a little more because I wanted it sooner ($21)
Make sure you get the size you want- a 2.4" was all that would fit in mine, but they make 2.8", 3.2" it all the way to 7" (which is about $70)
Here is the url for Dr. Ian Lee's website (KD8CEC
Read everything before you start. There are step by step procedures. You have to download the software to the radino-then copy his software and download on a microdisc(about $10) and put the microdisk in the display to download that.
It took me about a day of fussing around.  I downloaded the hex fiiles to the arduino so I had to download the bootloader.  I think I could have used the arduino code from github, so I don't know why he perferes to work with Hex
Andy - KM4TRT