Topics

uBITX AGC - Adafruit TPA2016, A Success! #ubitx

Richard E Neese
 

can some one doe a wire up on this board and how to add it in ?

Tim Gorman
 

Respectfully - the audio amp in the ubitx gives plenty of output to
drive either headphones or a communications speaker. I'm not sure what
additional capability this unit will offer.

The ubitx does not provide stereo capability for music, there is no
left/right output from the receiver so the stereo capability of this
unit will be wasted.

You will be limited to a 6db gain unless you want to control it using
I2C. To do that you'll have to modify the ubitx software to allow you
to do that.

You may actually be better off with a TPA2012 where you can set gain
with a set of on-board switches and can turn one speaker off by
grounding the shutdown pin for one side or the other.

You will also need some kind of insulated jack for the speaker leads
since they can't be grounded in any way.

Since the ubitx only has single-ended outputs on the pre-amp you'll
have to make sure both the + and - input leads are fed through
capacitors.

The speaker leads need to be kept pretty short since they are carrying
300khz signals. I have no idea how that 300khz signal will impact the
operation of the ubitx. That signal could easily leak into unwanted
areas in the receiver.

The AGC in this unit is attractive but the other problems you will
encounter will make this a pretty involved project, especially writing
the operation of the unit into the ubitx software.

tim ab0wr





On Mon, 16 Apr 2018 15:54:54 -0700 "Richard E Neese" <kb3vgw@...>
wrote:

can some one doe a wire up on this board and how to add it in ?

John Scherer
 

Wow, just found this thread.  I currently use the nd6t AGC and as playing around with controlling the hang-time digitally, but it takes 6 pins.  I just placed an order for the TPA2016 so I'll be playing with this for sure.  It would be really awesome if KD8CEC (or anyone) could add a config page for this to the Nextion display and support for it CEC firmware!  I'd take a stab at it but after looking at the graphics editor for the Nextion display, I'll pass.  It'd take me weeks to figure that hot mess out ;-)

John - N0CTL 

Joe Puma
 

I like the ND6T but I think Id rather have an audio agc. How would you wire this up? In a V3 board??

 

Joe

 

 

Sent from Mail for Windows 10

 

From: John Scherer
Sent: Thursday, November 8, 2018 2:23 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBITX AGC - Adafruit TPA2016, A Success! #ubitx

 

Wow, just found this thread.  I currently use the nd6t AGC and as playing around with controlling the hang-time digitally, but it takes 6 pins.  I just placed an order for the TPA2016 so I'll be playing with this for sure.  It would be really awesome if KD8CEC (or anyone) could add a config page for this to the Nextion display and support for it CEC firmware!  I'd take a stab at it but after looking at the graphics editor for the Nextion display, I'll pass.  It'd take me weeks to figure that hot mess out ;-)

John - N0CTL 

 

Curt
 

Joe

I am contemplating same thing. Note the  nd6t website shows 2 different agc designs, and note the link to adding an RF gain control. This is one candidate location for the mosfet attenuator,  even without installing an RF gain control that so far I don't need. I also thought about it at the front of the audio chain. I wonder if the agc bias could be injected into the existing TR mosfet, if not easy to add a second mosfet there. Worth some experiments to see what works well.

Curt

Jim Sheldon
 

I don't know. Check the T_DO and T_CS pins on the test set and see if one of the connected to the same input pin on the Teensy as the encoder SW.

On Nov 8, 2018, at 1:23 PM, John Scherer <jrsphoto@...> wrote:

Wow, just found this thread.  I currently use the nd6t AGC and as playing around with controlling the hang-time digitally, but it takes 6 pins.  I just placed an order for the TPA2016 so I'll be playing with this for sure.  It would be really awesome if KD8CEC (or anyone) could add a config page for this to the Nextion display and support for it CEC firmware!  I'd take a stab at it but after looking at the graphics editor for the Nextion display, I'll pass.  It'd take me weeks to figure that hot mess out ;-)

John - N0CTL