开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. BITX20
  2. Messages
Expanded Topics Messages Polls
Date
Re: PTT pop hack

 

Nice Raj
Thanks for the efforts in arriving at the solution.
sarma
?vu3zmv

On Sun, Mar 5, 2017 at 12:03 PM, Raj vu2zap <vu2zap@...> wrote:
Folks,

After much poking and probing with instruments I found the reason for the power pop when you press the PTT.

When PTT is pressed the TX voltage floods the mic preamp. Capacitor C122 charges up and the charging current flows into t4 and then
D15 - thereby for a fraction of a second the carrier leaks through and if you are listing with another RX you will hear a "tong" kind of sound.

Solution is to stop this flow through the diode then R106 - R220 to ground.

In my analog VFO version I desoldered the R106's center pin and put in a 0.1 capacitor in series. This stops the capacitor charge current from routing though the mixer diode.

For better measure add a 1K resistor across C107. I found a constant 30mV there which was unbalancing my diodes and the carrier balance pot R106 was more to clockwise than needed!

For the digital VFO board or boards without R106 trimmer, cut the track between D20 and R38 and solder a smd 0.1 cap there.

Result is a significantly reduced pop which is not bothersome anymore.

Farhan please incorporate this hack.

Cheers for a pop free Sunday!

--
Raj, vu2zap
Bengaluru, South India.








--
Regards
Sarma
?
Re: uBITX - A reboot of the old BITX

 

T10 is same. T11 is not really a trifilar transformer. Instead, it is an 8t:10t transformer on an ft3743. As there is no dc through T11, it can handle 10 watts of rf.
- f

On 5 Mar 2017 5:21 p.m., "VK3HN" <prt459@...> wrote:

T10 and T11 look like all the other trifilar FT37-43 transformers but as they are both handling power I assume they need something bigger. Ashar, what cores did you use?


Also the top capacitors in the PA LPFs dont have values... c241, c245, ?c231, c235... are these required??
Re: uBITX - A reboot of the old BITX

 

T10 and T11 look like all the other trifilar FT37-43 transformers but as they are both handling power I assume they need something bigger. Ashar, what cores did you use?


Also the top capacitors in the PA LPFs dont have values... c241, c245, ?c231, c235... are these required??
Re: uBITX - A reboot of the old BITX

 

Excellent suggestion. I will try adding this. We need a break in the if chain anyway
- f

On 5 Mar 2017 4:17 p.m., "Yeonghwan Jun" <ds5siz@...> wrote:

Hi Mr. Farhan,


I glad that you finish to design new uBITX.

If you do not finish to design PCB. Can you make Header pattern on your PCB for IF signal.

Because I wish to connect your new uBITX with RTL-SDR receiver.

I think It will be very useful gear to operation HF.

please refer above link...


Thanks to read it. 73.
Re: Setting up Arudio environment for Rardio programming ?

 

开云体育

Check via Manage Libraries the version of Si5351 library. Probably it is at 2.0, whereas 1.1.2 might get things to work.

?

Ron – PA3FAT
Re: uBITX - A reboot of the old BITX

 

Hi Mr. Farhan,


I glad that you finish to design new uBITX.

If you do not finish to design PCB. Can you make Header pattern on your PCB for IF signal.

Because I wish to connect your new uBITX with RTL-SDR receiver.

I think It will be very useful gear to operation HF.

please refer above link...


Thanks to read it. 73.
Setting up Arudio environment for Rardio programming ?

[email protected]
 

Hi there

Im trying to figure out how to set up a proper programming environment for to program my Rarduino.


I have downloaded and installed the Arduino IDE environment. I have also managed to get hold of the original sketch from github.?
I also installed the si5351 library ( I think ) . Seems to refer to a Etherkit si5351 library.?

But I get loads of errormessages.

Im not sure if and how to properly set up the programming environment. Im sort of newbie to this.

Please advice. ?SM0JZT / Tilman
Re: KB1GMX on the BITX

philip yates
 

Thanks for that.

Phil-G7BZD

On Sat, Mar 4, 2017 at 11:43 PM, John Backo via Groups.Io <iam74@...> wrote:
qrp-Tech is part of the Yahoo group. It is not
in .

john
AD5YE
PTT pop hack

 

Folks,

After much poking and probing with instruments I found the reason for the power pop when you press the PTT.

When PTT is pressed the TX voltage floods the mic preamp. Capacitor C122 charges up and the charging current flows into t4 and then
D15 - thereby for a fraction of a second the carrier leaks through and if you are listing with another RX you will hear a "tong" kind of sound.

Solution is to stop this flow through the diode then R106 - R220 to ground.

In my analog VFO version I desoldered the R106's center pin and put in a 0.1 capacitor in series. This stops the capacitor charge current from routing though the mixer diode.

For better measure add a 1K resistor across C107. I found a constant 30mV there which was unbalancing my diodes and the carrier balance pot R106 was more to clockwise than needed!

For the digital VFO board or boards without R106 trimmer, cut the track between D20 and R38 and solder a smd 0.1 cap there.

Result is a significantly reduced pop which is not bothersome anymore.

Farhan please incorporate this hack.

Cheers for a pop free Sunday!

--
Raj, vu2zap
Bengaluru, South India.
Re: SolderSmoke Podcast 194

 

SolderSmoke-Podcast is aweseome!

Made me getting the BITX40 this year. My first transceiver!

I'm listening backwards...episode 143 now

Found SPART. Thank you!
--
Pierre

DO2PAB
Re: uBITX - A reboot of the old BITX

 

For lower current needs, there are some transformers available from minicircuits too. I haven't used them, though.

- f

On Sun, Mar 5, 2017 at 11:06 AM, Ashhar Farhan <farhanbox@...> wrote:
buy the cores from W8DIZ and wind them yourself.

- f

On Sun, Mar 5, 2017 at 11:01 AM, Eldon Brown <eldonb46@...> wrote:

On Sat, Mar 4, 2017 at 8:33 PM, Ashhar Farhan <farhanbox@...> wrote:
I will change the designation to 2N3904. I use the trifilar transformers even where I need a bifilar as it it reduced the inventory. We just leave the extra wiring unused. I have a box full of trifiilar wound, FT37-43 that I can solder in anywhere.

- f

f,

What is your source for the Trifilar FT37-43, for our replacements, Thanks.


Regards,
Eldon Brown

73 - Eldon - WA0UWH -




Re: uBITX - A reboot of the old BITX

 

buy the cores from W8DIZ and wind them yourself.

- f

On Sun, Mar 5, 2017 at 11:01 AM, Eldon Brown <eldonb46@...> wrote:

On Sat, Mar 4, 2017 at 8:33 PM, Ashhar Farhan <farhanbox@...> wrote:
I will change the designation to 2N3904. I use the trifilar transformers even where I need a bifilar as it it reduced the inventory. We just leave the extra wiring unused. I have a box full of trifiilar wound, FT37-43 that I can solder in anywhere.

- f

f,

What is your source for the Trifilar FT37-43, for our replacements, Thanks.


Regards,
Eldon Brown

73 - Eldon - WA0UWH -



Re: uBITX - A reboot of the old BITX

 


On Sat, Mar 4, 2017 at 8:33 PM, Ashhar Farhan <farhanbox@...> wrote:
I will change the designation to 2N3904. I use the trifilar transformers even where I need a bifilar as it it reduced the inventory. We just leave the extra wiring unused. I have a box full of trifiilar wound, FT37-43 that I can solder in anywhere.

- f

f,

What is your source for the Trifilar FT37-43, for our replacements, Thanks.


Regards,
Eldon Brown

73 - Eldon - WA0UWH -


Re: uBITX - A reboot of the old BITX

 

done

On Sun, Mar 5, 2017 at 10:03 AM, Ashhar Farhan <farhanbox@...> wrote:
I will change the designation to 2N3904. I use the trifilar transformers even where I need a bifilar as it it reduced the inventory. We just leave the extra wiring unused. I have a box full of trifiilar wound, FT37-43 that I can solder in anywhere.

- f

On Sun, Mar 5, 2017 at 9:31 AM, Mvs Sarma <mvssarma@...> wrote:
Ashhar could just change the name to 3904 and CAD , I suppose, permits such name change.

On Sun, Mar 5, 2017 at 3:43 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Those are 2n3904's.? The schematic shows bc849's because that was the symbol that was handy.? Somebody needs to email Ashhar a kicad 2n3904 symbol, as he badly needs one.


On Sat, Mar 4, 2017 at 02:00 pm, VK3HN wrote:

Ashar, looking at BC849 on Element14.

?




--
Regards
Sarma
?
Re: uBITX - A reboot of the old BITX

 

I will change the designation to 2N3904. I use the trifilar transformers even where I need a bifilar as it it reduced the inventory. We just leave the extra wiring unused. I have a box full of trifiilar wound, FT37-43 that I can solder in anywhere.

- f

On Sun, Mar 5, 2017 at 9:31 AM, Mvs Sarma <mvssarma@...> wrote:
Ashhar could just change the name to 3904 and CAD , I suppose, permits such name change.

On Sun, Mar 5, 2017 at 3:43 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Those are 2n3904's.? The schematic shows bc849's because that was the symbol that was handy.? Somebody needs to email Ashhar a kicad 2n3904 symbol, as he badly needs one.


On Sat, Mar 4, 2017 at 02:00 pm, VK3HN wrote:

Ashar, looking at BC849 on Element14.

?




--
Regards
Sarma
?
Re: uBITX - A reboot of the old BITX

 

Ashhar could just change the name to 3904 and CAD , I suppose, permits such name change.

On Sun, Mar 5, 2017 at 3:43 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Those are 2n3904's.? The schematic shows bc849's because that was the symbol that was handy.? Somebody needs to email Ashhar a kicad 2n3904 symbol, as he badly needs one.


On Sat, Mar 4, 2017 at 02:00 pm, VK3HN wrote:

Ashar, looking at BC849 on Element14.

?




--
Regards
Sarma
?
Re: Raduino temp

 

Yes, but it is about 3x the price that you can get them for from e-bay.

They are available in several colors; I like the blue with white characters.
Also common is red with black letters. The "original" is green with white
characters. They are all parallel input devices.

If the ad claims them to be "Arduino compatible", then they are the
right displays. They come in several versions and pinouts; essentially
the 14 pin version has no backlight and the 16 pin version does. Note
that 16 pins is standard, however. A given unit may have 16 pins, but
may not have a backlight. There is another standard pinout which uses
two rows of 8 pins. The connection is the same.

Another variation (which is quite recent) uses a piggyback board to
provide for serial connections, usually SDA and SCL (but it could be
the hardware serial port or any two pins with software serial). An even
more recent version incorporates the serial translation into the lcd
itself. These will also work for our purposes.

All of these devices have datasheets available somewhere. Find the
one which goes with yours. They contain much very useful information,
especially on software control.

john
AD5YE
Re: Raduino temp

Michael Davis
 

This is the display. Are they compatible with our Raduino??http://www.youdoitelectronics.com/osepp-16x2-lcd-display
Re: Raduino temp

Michael Davis
 

Thanks all. I was at the local electronics parts store and there was a $9 white backlit display module. It looked similar to ours. What is the specification for a differend display. Will this one "play" with the Bitx raduino? I think it was a 5 volt unit.?
Re: BITX40 PTT Noise

 

I tried shorting C114 and C110 and didn't do a thing. As a quick check I desoldered one leg of C114/110 and the kerchunk was greatly reduced. Still had some change over noise but no where near what it normally is.

73

Ken VA3ABN

On Sat, Mar 4, 2017 at 3:55 PM, AndyH <ahecker@...> wrote:
On Fri, Mar 3, 2017 at 08:24 pm, AndyH wrote:
On Fri, Jan 27, 2017 at 07:32 pm, AndyH wrote:

Jerry,

The archeology might have paid off.? I think this matches what Farhan mentioned and what others call the 'transistor across the cap' fix.? I'll give it a shot.

Picture in our archive from K5DNL: ?/g/BITX20/photo/2855/5?p=Name,,,20,1,0,0

The parts references appear to be from the QRPKits BITX20A schematic - page 33 from here: ?

Looks like break the base connection of Q12 in that schematic (the base of Q5 in the HFSigs BITX40) and install a 2N7000 FET along with a 4K7 and 10uF.

Thanks all - off to order some 2N7000s...

73

?

I just completed this mod and it didn't work.? The radio appears to function normally, but the audio click and RF power spike remains unchanged.


Can anyone recommend a fix for this PTT audio spike that works for the BITX40 boards please?

73

Andy

?Next step...

On Fri, Jan 27, 2017 at 10:22 am, Jerry Gaffke wrote:

Try post 20828:

"Farhan mentioned this during his interview with Tom,?. He felt it was due to the cap C114 around the audio preamp Q16, holding the amp on for a bit when that rig is switched into transmit. I wouldn't be surprised that C110 might also be holding U1 on as well.? He thought about placing a transistor across the cap to discharge it when going into transmit. Drive the transistor from the xmit?voltage."

?

I left the 2N7000 across the base of Q5 as it didn't seem to do anything.? Next I used the same 2N7000 circuit around C114 to short the cap when switching to transmit.? The RF spike increased (about 400 mW) and now I have a strong click when PTT is activated and a smaller click when PTT is released.

I'll try C110 next.

73
92581 - 92600 of 115539