Date   
Re: TX relay problem

Biju Apkrcl
 

It is a common phenomena on ubitx. Some steps to avoid this


1. Replace the mic+ PTT wire with shielded cable. Good quality usb cable can be use.

2. Keep some distance between ubitx and Linier power amplifier.

3. Give earth connection to ubitx case and pa.


This problem will solve with the 1st point itself.




If the ubitx does not come back to receiver mode after transmitting, simply replace the Rx/Tx relay with a good quality relay just like O/E/N make.



 D e VU2TDD
BIJU. A. P.
MARGAO, GOA

On Mon, 13 Apr 2020, 07:58 Dr M T Thomas VU3NWB, <vu3nwb@...> wrote:
Thanks a lot dear Evan. Now it is working.

On Wed, 1 Apr, 2020, 2:40 AM Evan Hand, <elhandjr@...> wrote:
Dr. M T Thomas,

What you describe is a common problem with the uBiTx line of transceivers.  It is most often caused by RF getting into the rig, most likely from either the microphone cord or the coax shield. The best way to verify is to connect to an RF dummy load and see if it happens then.  If it does not stick in transmit mode, then it is RF getting back into the microcontroller.

Two solutions and both can be done.
1 - Put a common mode choke or snap-on ferrite in or on the coax from the antenna.  This is to keep RF out of the radio/shack.
2 - Put a snap-on ferrite on the microphone cord just before the plug and/or add 0.1 uF bypass capacitors on the PTT and microphone input.

Also, be sure that you have good earth ground on the case of the uBiTx.

It always helps to include the version of BiTx when asking for help on this site.  There are multiple models and versions of the BiTx radios, and the best solution can be based on which one you have the issue with.

Hope this helps.
73
Evan
AC9TU

Re: TX relay problem

Dr M T Thomas VU3NWB
 

Thanks a lot dear Evan. Now it is working.


On Wed, 1 Apr, 2020, 2:40 AM Evan Hand, <elhandjr@...> wrote:
Dr. M T Thomas,

What you describe is a common problem with the uBiTx line of transceivers.  It is most often caused by RF getting into the rig, most likely from either the microphone cord or the coax shield. The best way to verify is to connect to an RF dummy load and see if it happens then.  If it does not stick in transmit mode, then it is RF getting back into the microcontroller.

Two solutions and both can be done.
1 - Put a common mode choke or snap-on ferrite in or on the coax from the antenna.  This is to keep RF out of the radio/shack.
2 - Put a snap-on ferrite on the microphone cord just before the plug and/or add 0.1 uF bypass capacitors on the PTT and microphone input.

Also, be sure that you have good earth ground on the case of the uBiTx.

It always helps to include the version of BiTx when asking for help on this site.  There are multiple models and versions of the BiTx radios, and the best solution can be based on which one you have the issue with.

Hope this helps.
73
Evan
AC9TU

Re: Circuit for second PTT that will mute Mic but allow line-in...

John (vk2eta)
 

Hi Rob,

I use an electret, a low cost Baofeng style microphone with the capsule replaced by the one supplied with the uBitx kit and larger holes in front of the capsule.

I use an SSM2167 speech compressor module between the Mic and the radio Mic input fed through a trim pot to bring the max volume to acceptable levels. See http://ubitx.net/tag/ssm2167/ for details if you are interested. It really increases the average power on SSB.

Not sure about using the bias circuit voltage.

For powering the additional circuits in my first build I added a connector on the Raduino to pickup the 5V. On my second build I simply added another 5V regulator and that's a simpler option IMO.

Hope that helps.

73, John

Re: nextion display

pete torrance <wayfound2000@...>
 

thats great thankyou Evan

Re: Trying to diagnose my uBitx v5 #ubitx-help #v5 #ubitx

columbustalley@...
 

On Sun, Apr 12, 2020 at 06:40 PM, Arv Evans wrote:
First time you keyed up one rig directly 
into the other you probably burned the output MOSFET devices on 
the one transmitting, but just before it blew it probably destroyed parts 
of the receiver front-end circuitry in the receive unit.
First of all I would like to say thank you for your help and reply it's really appreciated.  I really want to get my radio working!

I really hope that I didn't fry anything.  During that test I was using a 12v 500ma power supply.  I'm guessing that's still enough power to destroy something?
It also indicates that your Arduino and display are 
probably still working properly.
Yes the Arduino and display still work.  The CAT control is working and when tuning the audio output definitely changes.  The uBITX Manager is working as well.

My guess is that these rigs are repairable, but you may need lots of help 
from the experts on this group before you have a working rig again.
That's bad news.  I'm going to mount my antenna to my car and see if things improve.  If not then I might need to call this a learning experience and order a new v6 kit.  = (

Re: Trying to diagnose my uBitx v5 #ubitx-help #v5 #ubitx

columbustalley@...
 

How are you mounting the antenna?
I just have the antenna sitting on the floor.  I did not know that it grounded to the car.  Duh!  I'll go attach it to the car and see if there is any change.
How is the radio receiving other signals?  Does it sound good listening to SSB signals on 20/40/80m?
Unfortunately I'm not really sure how to do that.  I don't know what frequencies to listen on and at what times.  All I ever hear is static.

Re: nextion display

Evan Hand
 

I have not done a v3, however, the differences from a v4 are mostly in the audio, so yes you should be able to.  

Checked on Github:
https://github.com/phdlee/ubitx/releases/tag/v1.20

There are v234 files in the archive, so yes, it should work.  Be sure to use the correct version for the screen that you will be using.

73
Evan
AC9TU

Re: Trying to diagnose my uBitx v5 #ubitx-help #v5 #ubitx

Arv Evans
 

Several ideas come to mind:

"I've assembled two uBitx v5's and was able to send and receive 
 messages on JS8Call by putting a wire directly between the two."

Whoa!  Did you read the instructions where it says to use a properly 
terminated 50 ohm antenna?  First time you keyed up one rig directly 
into the other you probably burned the output MOSFET devices on 
the one transmitting, but just before it blew it probably destroyed parts 
of the receiver front-end circuitry in the receive unit.  Sending several 
watts of RF into into the receive end of a sensitive receiver cannot be 
good!

Do you have access to an SWR bridge, a dummy load, a DVM, and an 
RF detector to use with the DVM?  Normally you would not need these 
but after transmitting directly into your receiver you are probably going 
to need some test equipment and the knowledge to use it.

At this point you will have to use the schematic drawing to trace voltage 
and signal levels through the circuitry.  Start with voltages, then once 
they all look good you can start tracing signals in transmit mode.  
Since you can still tune the rig the Si5351 synthesizer is probably still 
OK.  That is good.  It also indicates that your Arduino and display are 
probably still working properly.

My guess is that these rigs are repairable, but you may need lots of help 
from the experts on this group before you have a working rig again.  
Start by measuring DC voltages at critical points (mentally divide the 
circuit into modules and check supply voltages to each module).  Make 
a list of observed voltages versus where you observed them and post 
it to this forum.  Others can tell you where these voltages look good 
and where they look strange.  

If you have a nearby ham who has several years of circuit repair 
experience, that person may be able to provide some help and make 
the repair go faster.  

Arv  K7HKL
_._




On Sun, Apr 12, 2020 at 4:03 PM <columbustalley@...> wrote:
Hello everyone.  I've assembled two uBitx v5's and was able to send and receive messages on JS8Call by putting a wire directly between the two.  I'm running the newest CEC firmware.  I also have CAT control and my audio interface is a simple USB sound card.

I purchased an antenna so I can try to receive messages in JS8Call from other hams.  The antenna is a Tram 3500 which is a CB antenna and should work fine for the 10 meter band based on my research.

I connected the shield of the antenna to the black wire, and the signal to the grey wire.  Loaded up JS8Call and nothing.  Maybe there's just nobody transmitting?

Unfortunately I don't have the second radio on hand to use for testing.

Then I disconnected the antenna and to my surprise there was no change on the waterfall.  I'm a beginner but that doesn't sound normal to me.  Here is a screenshot half of the waterfall is with the antenna plugged in and the other half is with the antenna unplugged.

https://i.imgur.com/5YfITTE.png

I guess I have two questions.

Is there something wrong with my radio?

Are these not radio signals on the waterfall?  Is it just electrical noise?

Thanks!

Re: Trying to diagnose my uBitx v5 #ubitx-help #v5 #ubitx

 

On Sun, Apr 12, 2020 at 06:03 PM, <columbustalley@...> wrote:
Tram 3500
Hi,

How are you mounting the antenna?  It will need to sit on a large, flat, metal surface so the base can couple to it and provide the ground plane for the antenna (normally this is done by the car body).  If you have nothing like that, you will need to run some radial wires out from the base.  If the antenna is sitting on the ground, radial length doesn't matter, just put a bunch 4' or longer around the base.  If the antenna is elevated, then run two or more 8' long out from the base.

How is the radio receiving other signals?  Does it sound good listening to SSB signals on 20/40/80m?

73,


Mark

nextion display

pete torrance <wayfound2000@...>
 

can i fit a nextion display to a v3 ubitx ?
73 pete G4HAK

v3 microphone info ubitx

pete torrance <wayfound2000@...>
 

thought this might be useful
have a  ubitx v3 which was working great exept mic gain was v low. had a power mic DM510U handy so wired and connected it. put a 2mfd blocking cap in series with mic input line. works a treat and can control mic gain with var resistor already built into the mic. simples. and saved all those component changes!
all the best

Trying to diagnose my uBitx v5 #ubitx-help #v5 #ubitx

columbustalley@...
 

Hello everyone.  I've assembled two uBitx v5's and was able to send and receive messages on JS8Call by putting a wire directly between the two.  I'm running the newest CEC firmware.  I also have CAT control and my audio interface is a simple USB sound card.

I purchased an antenna so I can try to receive messages in JS8Call from other hams.  The antenna is a Tram 3500 which is a CB antenna and should work fine for the 10 meter band based on my research.

I connected the shield of the antenna to the black wire, and the signal to the grey wire.  Loaded up JS8Call and nothing.  Maybe there's just nobody transmitting?

Unfortunately I don't have the second radio on hand to use for testing.

Then I disconnected the antenna and to my surprise there was no change on the waterfall.  I'm a beginner but that doesn't sound normal to me.  Here is a screenshot half of the waterfall is with the antenna plugged in and the other half is with the antenna unplugged.

https://i.imgur.com/5YfITTE.png

I guess I have two questions.

Is there something wrong with my radio?

Are these not radio signals on the waterfall?  Is it just electrical noise?

Thanks!

Re: Circuit for second PTT that will mute Mic but allow line-in...

Rob French (KC4UPR)
 

Will definitely keep you in the loop with my progress.

Were you envisioning a dynamic mic with this, or electret?  I'm planning on putting together a little electret mic driver, but then I was thinking, could I just use the bias from the PTT circuit???  But I guess that would be a pretty low voltage (0.9V?) available there at the junction of R3 and D1, so probably not enough to drive the electret element...

Re: #ubitxv6 #ubitxv6

Reed N
 

https://groups.io/g/BITX20/files/V6_PCB_Photos/uBITX_v6_PCB.zip

^ There's a picture that was uploaded on another thread. Is that not precise enough for your needs?


Reed

#ubitxv6 #ubitxv6

alfred.s@...
 

Hi all, does anyone know the *exact* dimensions of the v6 board incl. protrusions (for case selection ;-)?
Thanks to all!
KR Alfred

Re: Circuit for second PTT that will mute Mic but allow line-in...

John (vk2eta)
 

Hi Rob,

Yes regarding the blend control that was what I had in mind.

Regarding feeding 12V to the circuit and connecting the PTT via the diode it should work fine as the Arduino sketches I have seen use the digitalread function for the PTT (although it is an analog input) and therefore will read a logical zero for anything below 2.2V (at 5VDC supply).

BUT, if you feed the circuit from the boards' main supply I would decouple the DC biasing voltage very carefully with resistors and capacitors otherwise you could have bad feedback through the variations in supply voltage.

Personally I would stick with 5V (or anything regulated below your supply line voltage) and well decoupled. Remember the audio voltage to the mic input is normally in the tens of millivolts so a) you don't need more than say a volt to be quite safe from spurious diode conduction and b) small variations in supply voltage will happily feedback in your mic input signal. Just my 2 cents.

Happy home-brewing.

Let us know what you come up with please.

73, John (VK2ETA)

Re: Circuit for second PTT that will mute Mic but allow line-in...

Rob French (KC4UPR)
 

John,

Thanks for the schematic!  That all makes sense to me, and it matches the math in your previous post, so I appreciate putting a picture to the words.

I know in the past I have connected my sound card output directly to my mic input without a trim pot any sort.  But I also haven't done any of the TX preamp adjustments to my uBITX that I've seen, so perhaps my audio, even if higher than the mic, was still fine getting into the TX stages.

As far as (potentially... haven't made my mind up) removing R1/R2 and replacing D2 with a trimpot (essentially a blend control, is what I think you are proposing?), I'd actually considered using an op amp mixer to blend the two inputs.  Your version would certainly be simpler.

If I wanted to ensure I had headroom for higher amplitude audio signals, could I replace the +5V with +12V?  Here's my thought.  Down where you have the Mic PTT, of course switching that to ground is how the PTT would work.  But, I was thinking I could have a diode connected between the Raduino and the switch.  The cathode end would be connected to the top of the switch, as would the "Mic PTT" input in the schematic you created.  Voltage present when the switch is open (+12V I think) wouldn't exceed the reverse voltage of the diode.  When the switch is closed, that would ground out both the Raduino PTT pin (via the diode) as well as the Mic PTT line in the circuit above.  Forward voltage drop across the diode would still land me in logical-zero land for 5V logic.   I'm sure I'm missing something here, but it makes sense in my head...

Thanks again for putting this together!

Regards,
-Rob KC4UPR

Re: Circuit for second PTT that will mute Mic but allow line-in...

John (vk2eta)
 

Hello Rob,

Replying to your first question: a mic output is generally in the 10s of mV. On top of my head I have 50mv as a typical mic input voltage for radios, so 100mv was king of a safe value for a mic output.

This means you will have to reduce the audio voltage from your computer line out (a trim pot would be the easiest).

Here is a hand sketch based on you new requirements. Only difference in that circuit is that it will cut the computer audio when the mic PTT is pressed.

I think that is better as it prevents sound card noise and other feedback from the computer audio circuit.

If you want to mix the computer audio with the audio coming from the mic, remove R1, R2, substitute D2 by a resistor (100K trim pot?).

I haven't built that circuit yet, so it is purely theoretical at this point.

73, John (VK2ETA)

Re: Noon question now noob question

Bill Cromwell
 

Hi,

There are several reverse polarity schemes that can protect the radio from damage in a reverse polarity episode. That is an episode of connecting DC power source with the positive and negative switched. Those are worthwhile to protect the radio gear. Any of us could do that at any time. That is not what fuses are for.

Reverse polarity is not the only thing that causes excessive current flow (shorts). The reverse polarity scheme is not going to keep an overload from burning your house down - maybe with you in it. An appropriate fuse will. They are cheap and easy. Cheap too, Easy too. Inexpensive, too. Uncomplicated, too. Is that clear enough? Please install fuses so we won't have to read about your untimely status as a silent key. Go ahead and operate without reverse polarity protection if you desire. It IS your gear.

73,

Bill KU8H

--
bark less - wag more

Re: Circuit for second PTT that will mute Mic but allow line-in...

_Dave_ AD0B
 

I would say the diodes you saw were to prevent any signals greater than the forward bias voltage, rather than signal routing. 
--
73
Dave
ADOB
Raduino bracket and Ham_Made_Keys