Date   
Dead Mic

Dennis
 

The enclosed mic doesn't work - can someone suggest a stateside replacement?

73, Dennis
W7DRW

Re: Dead Mic

R. E. Klaus
 

Pretty much any electret microphone element on Amazon, ebay, Digikey, etc will work just fine. They are polarity sensitive so you have to make sure you connect them properly.
Roxie  K1AUS

Re: Transmitter Mods

Sajid Rahum
 

Hi there Howard

Am going to be starting ubitx assembly tomorrow to piece it together and get 2822 replaced first. Next I wanted to ask if I can get hold of the 47uH inductor.  I was not sure where to order it from if you have a link will appreciate it; I have the other 2 remaining parts.

Much appreciated.

LM380 vs TDA2822 audio quality

Tom Cooper
 

Since I replaced my audio amp with an LM380 I just can't be more pleased with the results.  The LM380 has much less distortion for me on CW.  The 2822 must have been having input limiting and/or inter-modular distortion, with that square-wave buzziness being very noticeable on QRN and multiple loud CW sigs at once.  I had thought that Q70 was just being over-worked but that appears wrong.  I did do the 16K resisitor to ground from the base of Q70 mod before the 2822 had to be replaced and it seemed to help some at the time, but for the price of a resistor anything is worth trying.

I built the LM380 amp on a small piece of circuit board dead bug style.  Be sure to bypass the V+ pin close to the pin.  You can hear a lot of unwanted AM radio with sloppy wiring. 

Re: Dead Mic

Tom Cooper
 

You could probably use one out  of a dead phone or answering machine or other appliance.  That's what I did because my mic wouldn't work either.

Re: Need a Customs Form for import of Kees AGC and Pop-Thump kits into Canada. Can anybody let me know off-line? #ubitx-help

Kees T
 

all the ordering instructions are in the Files section under my call     K5BCQ

73 Kees K5BCQ

Re: #bitx40 #bitx40

qonita.salimah@...
 

Thank you for your reply..

I'd already double check my connection and wiring to the headphone jack. I also try another speaker, in case the problem is within the speaker. But the thing that happened is the system didn't show any sound at all. 

Thank you very much

Re: #bitx40 #bitx40

qonita.salimah@...
 

Did the potentiometer also affecting?

Re: W8TEE vft/tft questions

Jack, W8TEE
 

Thanks!!

Jack, W8TEE

On Sunday, May 27, 2018, 8:21:11 PM EDT, <tom.mccobb@...> wrote:


Turned out to be a combination of the encoder sending out 4 pulses, AND a bad 2560.  As soon as I swapped out the Arduino, all was well, and the code change made tuning behave better than ever.

Thanks for everyone's input.

Jack:  I have (and continue to) enjoyed Arduino Projects for Ham Radio.

Re: The new uBITX boards are here

Ashhar Farhan
 

The load on the Mosfet gates is of 130pf in parallel with the gate resistor : 220 ohms in this case. The reactance of the gate capacitance would be about - j50 towards, the higher end of the HF spectrum. Paralleling a resistor with the the gate produces a load impedance for the push-pull driver. As Allison noted, our driver chain does not have enough juice at the higher end of the spectrum, the higher impedance decreases the drive requirements. I came upon the 220 ohms experimentally. I tried values from 10K downwards. More than 1K rested in in-stability. The output starts tampering off below 1K and rapidly so below 470 ohms. I tabulated the results inthe logbook. I don't have access to it now.
- f

On Mon, 28 May 2018, 06:06 Kees T, <windy10605@...> wrote:
I think the 27 ohms has more to do with 50 ohm input impedance matching.

73 Kees K5BCQ

Re: BITX QSO Afternoon/Evening, Sunday, May 27, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Jack, W8TEE
 

Used to have a cabin north of North Bay. Black flies are just about zero fun.

Jack, W8TEE

On Sunday, May 27, 2018, 7:37:08 PM EDT, Tom VE3THR <muzzmobility@...> wrote:


greetings from black fly country guys...up in Sudbury Ontario EN96 tonight. End fed inverted L and a Buddy Stick vertical just ain't cuttin' it tonight. Weak sigs - worked John WA3FZW briefly so far. Will keep trying till dark.
73 Tom VE3THR

Re: LM380 vs TDA2822 audio quality

Ashhar Farhan
 

Good to know! 


On Mon, 28 May 2018, 07:18 w1eat via Groups.Io, <w1eat=yahoo.com@groups.io> wrote:
Since I replaced my audio amp with an LM380 I just can't be more pleased with the results.  The LM380 has much less distortion for me on CW.  The 2822 must have been having input limiting and/or inter-modular distortion, with that square-wave buzziness being very noticeable on QRN and multiple loud CW sigs at once.  I had thought that Q70 was just being over-worked but that appears wrong.  I did do the 16K resisitor to ground from the base of Q70 mod before the 2822 had to be replaced and it seemed to help some at the time, but for the price of a resistor anything is worth trying.

I built the LM380 amp on a small piece of circuit board dead bug style.  Be sure to bypass the V+ pin close to the pin.  You can hear a lot of unwanted AM radio with sloppy wiring. 

Re: BITX40 CW Carrier Mod - CW Waveform shaping ? #bitx40

Dexter N Muir
 

How about a clamping FET like the anti-thump? (for the forgetful most :)  )
73
Dex ZL2DEX

Re: Dead Mic

Mike Lichtman
 

Pacific Antenna has a mic kit that will work.73 Mike Kf6kxg

Re: audio dropping out

 

It should refer to uBitx! Unless you tell us which board you are referring to then only someone can answer your questions!

At 27/05/2018, you wrote:

Raj,

I've seen many many references to the uBITX here. Allison is working on a mod to flatten the power curve across bands. So, I am confused what does the "u" stand for in "Bitx20/40/u"?. This is where Ashar sent me to ask questions? Was I mistaken?



Thanks,

Re: The new uBITX boards are here

Jerry Gaffke
 

As I say, it's curious.
And I still haven't figured any of this out.
My simulations often gave results that I found counterintuitive.
Never did graduate to messing with actual parts.

In the fourth paragraph of post 22597, Allison warns against too high of a drive impedance.
Though that likely pertains mostly with DC supplies well over 12v.
 
In post 41227 I report simulating the uBitx final in LT spice.  When driving the FET's with 
a 1:1 transformer I saw the input impedance drop from around 50 ohms at 7mhz
down to around 12 ohms at 30 mhz.  So 220 ohms seemed out of the ballpark. 

The Vishay datasheet says the IRF510 has an input capacitance of 180pf typical
when Vds is held constant at 25v.  I assume it's much more in this amp due to the Miller effect.

But I can't argue with what works. 

Jerry


On Sun, May 27, 2018 at 07:54 pm, Ashhar Farhan wrote:
The load on the Mosfet gates is of 130pf in parallel with the gate resistor : 220 ohms in this case. The reactance of the gate capacitance would be about - j50 towards, the higher end of the HF spectrum. Paralleling a resistor with the the gate produces a load impedance for the push-pull driver. As Allison noted, our driver chain does not have enough juice at the higher end of the spectrum, the higher impedance decreases the drive requirements. I came upon the 220 ohms experimentally. I tried values from 10K downwards. More than 1K rested in in-stability. The output starts tampering off below 1K and rapidly so below 470 ohms. I tabulated the results inthe logbook. I don't have access to it now.
- f

Re: The new uBITX boards are here

Ashhar Farhan
 

Jerry, 

This is science at work. We often get unexpected results. Those are the ones that pump up our adrenalin, the game is afoot, Watson! Something unexpected has shown up. Often times, in our bid to functionally decompose, we ten to ignore that the results from string up all the blocks together is also a result of how well they keep working to the spec under changed conditions. 
There is some interactivity between the driver output behaviour and the FET finals. This needs investigations on a rainy day.
- f

On Mon, May 28, 2018 at 9:35 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
As I say, it's curious.
And I still haven't figured any of this out.
My simulations often gave results that I found counterintuitive.
Never did graduate to messing with actual parts.

In the fourth paragraph of post 22597, Allison warns against too high of a drive impedance.
Though that likely pertains mostly with DC supplies well over 12v.
 
In post 41227 I report simulating the uBitx final in LT spice.  When driving the FET's with 
a 1:1 transformer I saw the input impedance drop from around 50 ohms at 7mhz
down to around 12 ohms at 30 mhz.  So 220 ohms seemed out of the ballpark. 

The Vishay datasheet says the IRF510 has an input capacitance of 180pf typical
when Vds is held constant at 25v.  I assume it's much more in this amp due to the Miller effect.

But I can't argue with what works. 

Jerry


On Sun, May 27, 2018 at 07:54 pm, Ashhar Farhan wrote:
The load on the Mosfet gates is of 130pf in parallel with the gate resistor : 220 ohms in this case. The reactance of the gate capacitance would be about - j50 towards, the higher end of the HF spectrum. Paralleling a resistor with the the gate produces a load impedance for the push-pull driver. As Allison noted, our driver chain does not have enough juice at the higher end of the spectrum, the higher impedance decreases the drive requirements. I came upon the 220 ohms experimentally. I tried values from 10K downwards. More than 1K rested in in-stability. The output starts tampering off below 1K and rapidly so below 470 ohms. I tabulated the results inthe logbook. I don't have access to it now.
- f


Re: Raduino 4 Line Single Sided PCB boards

Rahul Srivastava
 

Thanks ..!! for the suggestion yes its a very useful addition given the variants of code available. I will update the pcb in couple of days.

73

Rahul VU3WJM 

Re: Need a Customs Form for import of Kees AGC and Pop-Thump kits into Canada. Can anybody let me know off-line? #ubitx-help

Peter LB0K
 

Wouldn't the Canadian Customs and Excise organisations website be a good place to start?
Alternatively check with the part of the postal service who probably deal with these matters.

Receive FM Radio Station #bitx40

qonita.salimah@...
 

Hello everyone..

Finally my bitx, showing some audio signal, but the sound that I've got is FM Radio, at 89-90 MHz.. Any clue why this could happen?

I didn't attach the DDS.

Thankyou very much