Date   
Re: My uBITX is alive!!

Gary Shriver
 

I’m such a nubee I am still waiting on shipment of my uBitx.  But what is the difference between the KD8CEC firmware when compared to the stock firmware that comes with the uBitx? 

 

73-Gary

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of bill richardson
Sent: Wednesday, February 14, 2018 2:06 PM
To: BITX20@groups.io
Subject: Re: [BITX20] My uBITX is alive!!

 

Dave,

 

Now upgrade to KD8CEC firmware and you will be amazed. 


On Feb 14, 2018, at 4:21 PM, Jack Purdum via Groups.Io <jjpurdum@...> wrote:

Wow...nice job!

 

Jack, W8TEE

 


From: David Robertson <kd1na363@...>
To: BITX20@groups.io
Sent: Wednesday, February 14, 2018 12:47 PM
Subject: [BITX20] My uBITX is alive!!

 

Everyone.
Last night my uBITX took ti's first breath of life. Even worked a couple of QSOs. Attached are some pictures. Please note that I installed the 4.7K resister on the radinio board for CW pull up instead of installing it in the wiring with the CW jack on the front panel. Because of the case size I removed the heat sinks from the finals and using mica insulators I mounted them to the back panel. The heat sinks that were supplied had metal ridges on the back that had to be removed so they could mount flat on the bolts that fastened the finals to the rear panel.

The radio works on 80 through 10 meters with decreasing power as you go up in frequency. I get about 15 watts out on 80 down to 5 watts on 20.

The frequency calibration seems to be very close. In performing the bias adjustment I discovered that I could only adjust the current for each final to about 83 ma with the pot set fully CCW. So to even the shared current of the two finals I adjusted them to 60ma each with the total of 120 final bias current. The little voltage regulator in the final circuit was working correctly supplying 5 Volts to the bias circuit during transmit. Though this radio is not in the same league as my Elecraft equipment it is a radio I can have a lot of fun with.
73 Dave  KD1NA

 

Re: Raduino Replacemnt, COMING SOON!

Nick VK4PP
 

Just an update,
I have incorporated the optional PTT POP fix on the board too as per: https://groups.io/g/BITX20/wiki/UBitx-PTT-POP-Fix

And an extra cap for power filtering...
And extra holes for more power resistors.

Re: phone + ssh/vnc to raspberry pi was Raduino Replacemnt, COMING SOON!

Joe Puma
 

Okay. That wasn’t the method then. Not even sure that’s even an option I was foggy on the details but you create a file called ssh and put it in the boot folder on Sd card. When it finds the file on boot it enables ssh and then deletes file. 


Joe


On Feb 14, 2018, at 5:41 PM, Fred Buecker <tfbiii2002@...> wrote:

The settings do not disappear on the next reboot. This enables the SSH server and then it stays on.

On Feb 13, 2018 8:01 PM, "Joe Puma" <kd2nfc@...> wrote:
If you’re trying to access a rpi from ssh on a fresh install or headless when Ssh is not enabled you can edit the boot.txt file on the SD card from another computer and add “ssh” (without quotes) to the file. You will have one shot to boot up and connect via Ssh. The setting will disappear on Next reboot. 

Joe
KD2NFC 



On Feb 13, 2018, at 6:00 PM, Doug W <dougwilner@...> wrote:

I figured it was time to free this thread from VK4PLN's post.

There is another option if you can beg, borrow or otherwise obtain a computer for the very first set up.  Frustratingly SSH is disabled on most of the pi distros by default so you will need another box to set this up with a card reader/writer.  Also if you are using a windows machine you need a way to write linux files.  I used a demo version of Paragon ExtFS https://www.paragon-software.com/home/linuxfs-windows/#  Once done you can SSH or VNC (for gui) into your pi via wifi using your phone or tablet as a monitor.  I fumble around with the phone screen keyboard for minor stuff and use VNC or PuTTY on my desktop for real work.  I don't see why you couldn't use a bluetooth or usb/otg keyboard connected to your phone.  This is a good article to get you started https://caffinc.github.io/2016/12/raspberry-pi-3-headless/  I currently have 3 pis running with this set up.  If you go this route you don't need all the USB ports on the Pi3 and can go with the cheaper ZeroW.  Just make sure you get the W with wifi not the plain zero.

Re: My uBITX is alive!!

bill richardson
 

Lots of good info on his blog site that should be the first place you should look:
http://www.hamskey.com/2018/02/cat-support-ubitx-firmware-cec-version.html?m=1

It’s like comparing a moped to a corvette ;) fixed a lot of bugs and usability is far superior with his updates. 

Things like controlling the ubitx via your computer via the USB port using  programs like FLdigi and others. He has also made a ubitx manager tool for adding memories and locking down TX on the radio to just the ham bands.. saving your settings and more... it really makes the ubitx shine!


On Feb 14, 2018, at 6:29 PM, Gary Shriver <gshriver@...> wrote:

I’m such a nubee I am still waiting on shipment of my uBitx.  But what is the difference between the KD8CEC firmware when compared to the stock firmware that comes with the uBitx? 

 

73-Gary

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of bill richardson
Sent: Wednesday, February 14, 2018 2:06 PM
To: BITX20@groups.io
Subject: Re: [BITX20] My uBITX is alive!!

 

Dave,

 

Now upgrade to KD8CEC firmware and you will be amazed. 


On Feb 14, 2018, at 4:21 PM, Jack Purdum via Groups.Io <jjpurdum@...> wrote:

Wow...nice job!

 

Jack, W8TEE

 


From: David Robertson <kd1na363@...>
To: BITX20@groups.io
Sent: Wednesday, February 14, 2018 12:47 PM
Subject: [BITX20] My uBITX is alive!!

 

Everyone.
Last night my uBITX took ti's first breath of life. Even worked a couple of QSOs. Attached are some pictures. Please note that I installed the 4.7K resister on the radinio board for CW pull up instead of installing it in the wiring with the CW jack on the front panel. Because of the case size I removed the heat sinks from the finals and using mica insulators I mounted them to the back panel. The heat sinks that were supplied had metal ridges on the back that had to be removed so they could mount flat on the bolts that fastened the finals to the rear panel.

The radio works on 80 through 10 meters with decreasing power as you go up in frequency. I get about 15 watts out on 80 down to 5 watts on 20.

The frequency calibration seems to be very close. In performing the bias adjustment I discovered that I could only adjust the current for each final to about 83 ma with the pot set fully CCW. So to even the shared current of the two finals I adjusted them to 60ma each with the total of 120 final bias current. The little voltage regulator in the final circuit was working correctly supplying 5 Volts to the bias circuit during transmit. Though this radio is not in the same league as my Elecraft equipment it is a radio I can have a lot of fun with.
73 Dave  KD1NA

 

Re: error on verify raduino ino

Jack, W8TEE
 

What are the error messages you're getting?

Jack, W8TEE



From: Michael Monteith via Groups.Io <michael_r_monteith@...>
To: BITX20@groups.io
Sent: Wednesday, February 14, 2018 8:15 PM
Subject: Re: [BITX20] error on verify raduino ino

Jack,
 I assume he must have his fixed.  I've got the same error.  I'm running 1.8.5.  I have both the btix40 tab and the si5351.h tab.
I did notice when I installed the si5351 library it put it in:
C:\Users\username\Documents\Arduino\libraries
I even copied the folder to where the IDE libraries are:
C:\Program Files (x86)\Arduino\libraries
and restarted the IDE

 I thought while I was sitting here I'd load the sketch, compile it, and be able to play around with some ideas.   So not critical right now.  Just when you get time.

73, Michael
KM4OLT


Re: My uBITX is alive!!

VE7WQ
 

Wonderful, congrats Dave,


Wednesday, February 14, 2018, you wrote:


DR> Everyone.

DR> Last night my uBITX took ti's first breath of life. Even worked a couple of

DR> QSOs. Attached are some pictures. Please note that I installed the 4.7K

DR> resister on the radinio board for CW pull up instead of installing it in the

DR> wiring with the CW jack on the front panel. Because of the case size I

DR> removed the heat sinks from the finals and using mica insulators I mounted

DR> them to the back panel. The heat sinks that were supplied had metal ridges

DR> on the back that had to be removed so they could mount flat on the bolts

DR> that fastened the finals to the rear panel.


DR> The radio works on 80 through 10 meters with decreasing power as you go up

DR> in frequency. I get about 15 watts out on 80 down to 5 watts on 20.


DR> The frequency calibration seems to be very close. In performing the bias

DR> adjustment I discovered that I could only adjust the current for each final

DR> to about 83 ma with the pot set fully CCW. So to even the shared current of

DR> the two finals I adjusted them to 60ma each with the total of 120 final bias

DR> current. The little voltage regulator in the final circuit was working

DR> correctly supplying 5 Volts to the bias circuit during transmit. Though this

DR> radio is not in the same league as my Elecraft equipment it is a radio I can have a lot of fun with.

DR> 73 Dave  KD1NA





73! Zsolt

VE7WQ


73! George

VE7WQ

uBitx LCD Viewing Angle and Replacement Hints Needed

Mike Lichtman
 

Good evening. I have my uBitx mounted in a cabinet that working well with 12w on 75m and 9 on 40m. The only problem is
I went to put it on a shelf on my operating desk and the viewing angle made the display unreadable. While not 
a new to electronics, I am new to playing with digital and lcd displays. Can anyone recommend a plug and play blue/white or black/white display
without the viewing angle concerns that is as close to the current opening size as possible? 73 Mike KF6KXG

Re: uBitx LCD Viewing Angle and Replacement Hints Needed

bill richardson
 

I had the same problem with my Bitx40. You just need to adjust the display contrast that’s the variable resistor on the back of the display board. 


On Feb 14, 2018, at 10:09 PM, Mike Lichtman via Groups.Io <tchrme@...> wrote:

Good evening. I have my uBitx mounted in a cabinet that working well with 12w on 75m and 9 on 40m. The only problem is
I went to put it on a shelf on my operating desk and the viewing angle made the display unreadable. While not 
a new to electronics, I am new to playing with digital and lcd displays. Can anyone recommend a plug and play blue/white or black/white display
without the viewing angle concerns that is as close to the current opening size as possible? 73 Mike KF6KXG

Re: uBitx LCD Viewing Angle and Replacement Hints Needed

Jack, W8TEE
 

Check out:

Terry King runs the shop and is great to work with and knows his stuff (EE type). Check out his software tutorials, too...they are worth a look if you're just getting started. Also, if you go with an I2C display like he sells for $5.50, you'll free up several I/O lines for other uses. Search this forum for posts relating to I2C interfacing with the µBITX.

Jack, W8TEE


From: Mike Lichtman via Groups.Io <tchrme@...>
To: BITX20@groups.io
Sent: Wednesday, February 14, 2018 10:09 PM
Subject: [BITX20] uBitx LCD Viewing Angle and Replacement Hints Needed

Good evening. I have my uBitx mounted in a cabinet that working well with 12w on 75m and 9 on 40m. The only problem is
I went to put it on a shelf on my operating desk and the viewing angle made the display unreadable. While not 
a new to electronics, I am new to playing with digital and lcd displays. Can anyone recommend a plug and play blue/white or black/white display
without the viewing angle concerns that is as close to the current opening size as possible? 73 Mike KF6KXG


Re: uBitx LCD Viewing Angle and Replacement Hints Needed

KC9SGV <kc9sgv@...>
 

I found this on a previous thread.
Get the 5V version, they say.
Should work fine, they say...


Bernie,
KC9SGV


On Feb 14, 2018, at 9:24 PM, Jack Purdum via Groups.Io <jjpurdum@...> wrote:

Check out:

Terry King runs the shop and is great to work with and knows his stuff (EE type). Check out his software tutorials, too...they are worth a look if you're just getting started. Also, if you go with an I2C display like he sells for $5.50, you'll free up several I/O lines for other uses. Search this forum for posts relating to I2C interfacing with the µBITX.

Jack, W8TEE


From: Mike Lichtman via Groups.Io <tchrme@...>
To: BITX20@groups.io
Sent: Wednesday, February 14, 2018 10:09 PM
Subject: [BITX20] uBitx LCD Viewing Angle and Replacement Hints Needed

Good evening. I have my uBitx mounted in a cabinet that working well with 12w on 75m and 9 on 40m. The only problem is
I went to put it on a shelf on my operating desk and the viewing angle made the display unreadable. While not 
a new to electronics, I am new to playing with digital and lcd displays. Can anyone recommend a plug and play blue/white or black/white display
without the viewing angle concerns that is as close to the current opening size as possible? 73 Mike KF6KXG


Re: Aluminum enclosure

Dave Bottom <ars.kd6az@...>
 

Hi Simon,

Yes, that is the part for mounting the Power Poles.  Available from Mouser Australia
As are the Hammond cases.


Dave WI6R



On Tue, Feb 13, 2018 at 4:42 PM, Simon Rumble <simon@...> wrote:
Hey Dave that's a beautiful rig. Nice work!

How do you panel mount the power poles? I'm just getting started with them and I haven't seen any panel mount versions. So how do you keep them in place? Is it something like this product? (Those are cheap but the postage to Australia is ruinous)

On Tue, 13 Feb 2018 at 09:25 Dave Bottom <ars.kd6az@...> wrote:
Here is mine in the Hammond 1402DV (V for Vented since the heat sinks are inside.)

Mentor-Knobs.jpg
Rear-View.jpg
​It's tight with the Volume Control mounted in between the display and the extrusion. So the PCB is mounted as close as you can get to the right side extrusion, then mark for the display and pot, with the encoder centered between the display and right side.

I used my own connectors for Mic, Headphones and Paddle plus Power Pole power connection all on the rear panel with the BNC antenna connector.

Room to later mount a USB cable as shown, I would have centered the Power Pole connector with the USB rear panel connection.
USB-Cable-Interface.jpg

Dave WI6R



On Mon, Feb 12, 2018 at 5:24 AM, John KC9OJV <greusel@...> wrote:
I ordered one of these: https://www.hammfg.com/part/1402D
I'm hoping I can work with the height of the Raduino OK.

John
KC9OJV




--
73 Dave WI6R

--
-- 
Simon Rumble <simon@...>
VK2VSR




--
73 Dave WI6R

Re: Micro BITx Audio Pot

Dave Bottom <ars.kd6az@...>
 

The one supplied has a 4 mm shaft while the encoder has a 6 mm shaft.
I found Mentor Knobs that had the same style for both shaft sizes.  See my photos posted or my QRZ page.

I ordered from Farnell in the UK (export site) and apparently they must ship a container to the US each day and then send by Mail as I paid a almost nothing to get them here in the US.

Dave WI6R

On Wed, Feb 14, 2018 at 4:02 AM, Robert Goodwin <bobgn1@...> wrote:

What is the shaft size on the provided audio pot in the uBITx?  It was 0.16 in the BITx40 but pictures of the uBITx parts make me think it might be different in the the uBITx.  I'm trying to get all the parts that I have to provide together before the kit arrives, and this knob is of interest.

Bob, N4HCI




--
73 Dave WI6R

Re: Raduino Replacemnt, COMING SOON!

Glenn
 

Ian, did you plan to have the NANO board as a plug in rather than solder in?   If so I think you might have height issues once the LCD is fitted.

glenn

Re: Raduino Replacemnt, COMING SOON!

Glenn
 

sorry, this was meant for Nic not Ian.

Re: Raduino Replacemnt, COMING SOON!

Nick VK4PP
 

HI Glen,

That decision is up to the builder... If socketing I imagine I2C LCD is going to be needed and/or remote mounting the LCD.
73

Re: Raduino Replacemnt, COMING SOON!

Glenn
 

OK
could also use longer header pins on the LCD if socketting the NANO.

Re: uBitx LCD Viewing Angle and Replacement Hints Needed

MVS Sarma
 

A little change of contrast potentometer ( JUST 5 DEGREES ON  EITHER SIDE OF PRESENT ) would also help orientation.
 Please on't turn too much.






Regards
MVS Sarma
 

On Thu, Feb 15, 2018 at 8:39 AM, Mike Lichtman via Groups.Io <tchrme@...> wrote:
Good evening. I have my uBitx mounted in a cabinet that working well with 12w on 75m and 9 on 40m. The only problem is
I went to put it on a shelf on my operating desk and the viewing angle made the display unreadable. While not 
a new to electronics, I am new to playing with digital and lcd displays. Can anyone recommend a plug and play blue/white or black/white display
without the viewing angle concerns that is as close to the current opening size as possible? 73 Mike KF6KXG


Re: Ubitx and 60 meters

Walter Robard Seiler <waltrseiler@...>
 

Thanks for that, I thought it might be something as simple as that

cheers and 73
WRS VE7CWS

Re: RD16HHF1 in the uBITX #ubitx

John <passionfruit88@...>
 

I have done a strait replacement of the IRF510s with RD16HHF1s. 
 
Here are the before and after values I got.
 
All tests done with uBitx VR1 drive level in the same position of approx 60% of range.
 
1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A total (factory setting) so assume 100mA in each final. 
(For info, Rx currents: 164mA no volume, about 209mA "normal" volume). 
- At 7.1Mhz:   10W, total current: 1.79A, of which PA current: 1.31A, therefore main board current 0.48A
- At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current: 1.0A,  therefore main board current 0.39A
- At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
- At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
 
 
2. IRF510s with 16.5V, 13.8V for main board. PA total idle current checked at 0.21A. 
(For info, Rx currents: 188mA no volume, about 230mA "normal" volume). 
- At 7.1Mhz:  19W, total current: 2.65A, of which PA current: 2.09A, therefore main board current 0.56A
- At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A, therefore main board current 0.40A
- At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A, therefore main board current 0.40A
- At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A, therefore main board current 0.42A
 
 
I haven't found a definitive reference for the safe and optimum values of the RD16HHF1s idle bias current but it seems to range from 200 to 500mA. So I would not recommend long term usage of the 500mA bias I used for these measurements.
I will reset mine to probably the 400-450mA value I read from some articles.
 
3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A PA idle current). 
- At 7.1Mhz:  10W,  PA current: 1.20A
- At 14.2Mhz: 9W,   PA current: 1.21A
- At 21.2Mhz: 4.5W, PA current: 0.65A
- At 28.1Mhz: 5.5W, PA current: 0.95A
 
 
4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA idle current). 
- At 7.1Mhz: 10W, PA current: 1.18A
- At 14.2Mhz: 9W, PA current: 1.26A
- At 21.2Mhz: 5W, PA current: 0.71A
- At 28.1Mhz: 6W, PA current: 1.11A
 
 
5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA idle current). 
- At 7.1Mhz:  13.5W, PA current: 1.95A
- At 14.2Mhz: 13.5W, PA current: 1.93A
- At 21.2Mhz: 6W,    PA current: 1.38A
- At 28.1Mhz: 9.5W,  PA current: 1.79A
 
 
 
Interesting observations:
 
A. The RD16HHF1 produces a much flatter power curver over frequency (in my device), although it shows a dip somewhere near the 15m band.
 
B. The IRF510 can produce some nice power in the lower frequencies when increasing the PA supply voltage, but it comes at the price of a steep power drop at higher frequencies.
 
C. The bias does not seem to influence the efficiency of the finals at full power with RD16HHF1, since biasing at 250 and 500mA produces essentially the same output for the same DC power input. Assuming distortion reduces with higher bias, can we assume a higher bias (within limits) is preferable? Any risk of thermal runaway?
 
D. The board main current (which includes the current in the driving stages of the power amplifier) does not seem to change with frequency from 20m onwards. Is this because the gain is pretty constant? If so, most of the drop in power with increasing frequency seems to be in the IRF510s, supporting the results obtained with the RD16HHF1s.
 
E. With the current uBitx PA circuit the RD16HHF1 seems limited in output, although not having the proper test equipment I can't say where the limitation occurs.
 
F. When I increased the drive through VR1 I noticed that at around 40% for the lower frequencies and at around 60% for the top frequencies I get a compression effect and the output does not increase much more from there on. I left it at 60% and got a positive feedback on the voice quality on my first QSO on 40m. Therefore I assume that the compression/clipping is not significant at that level (but I can't measure the sprectral purity).
 
 
So since my target was around 10W on 10m and 10 to 15W on 40m minimum I can say I have reached my goal just by changing the finals to RD16HHF1s and supplying the board with 13.8VDC (below the 15.2/15V stated in the respective datasheets of the RD16HHF1 and TDA2822).
 
To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and source pins of the RD16s to match, then soldered in place.
 
It would be interesting to compare these results with others who performed the finals swap on the stock uBitx.
 
Next is the installation of the TPA2016 audio amplifier with I2C controllable AGC.

This is a lot of fun.
 
All the best,
 
73, John (VK2ETA)
 



Re: RD16HHF1 in the uBITX #ubitx

Gordon Gibby <ggibby@...>
 

John, thank you for that extremely well documented information. Makes me much more interested in considering this. I wonder if the efficiency indicates that the circuit design could be improved?


On Feb 15, 2018, at 08:39, John <passionfruit88@...> wrote:

I have done a strait replacement of the IRF510s with RD16HHF1s. 
 
Here are the before and after values I got.
 
All tests done with uBitx VR1 drive level in the same position of approx 60% of range.
 
1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A total (factory setting) so assume 100mA in each final. 
(For info, Rx currents: 164mA no volume, about 209mA "normal" volume). 
- At 7.1Mhz:   10W, total current: 1.79A, of which PA current: 1.31A, therefore main board current 0.48A
- At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current: 1.0A,  therefore main board current 0.39A
- At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
- At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
 
 
2. IRF510s with 16.5V, 13.8V for main board. PA total idle current checked at 0.21A. 
(For info, Rx currents: 188mA no volume, about 230mA "normal" volume). 
- At 7.1Mhz:  19W, total current: 2.65A, of which PA current: 2.09A, therefore main board current 0.56A
- At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A, therefore main board current 0.40A
- At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A, therefore main board current 0.40A
- At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A, therefore main board current 0.42A
 
 
I haven't found a definitive reference for the safe and optimum values of the RD16HHF1s idle bias current but it seems to range from 200 to 500mA. So I would not recommend long term usage of the 500mA bias I used for these measurements.
I will reset mine to probably the 400-450mA value I read from some articles.
 
3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A PA idle current). 
- At 7.1Mhz:  10W,  PA current: 1.20A
- At 14.2Mhz: 9W,   PA current: 1.21A
- At 21.2Mhz: 4.5W, PA current: 0.65A
- At 28.1Mhz: 5.5W, PA current: 0.95A
 
 
4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA idle current). 
- At 7.1Mhz: 10W, PA current: 1.18A
- At 14.2Mhz: 9W, PA current: 1.26A
- At 21.2Mhz: 5W, PA current: 0.71A
- At 28.1Mhz: 6W, PA current: 1.11A
 
 
5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA idle current). 
- At 7.1Mhz:  13.5W, PA current: 1.95A
- At 14.2Mhz: 13.5W, PA current: 1.93A
- At 21.2Mhz: 6W,    PA current: 1.38A
- At 28.1Mhz: 9.5W,  PA current: 1.79A
 
 
 
Interesting observations:
 
A. The RD16HHF1 produces a much flatter power curver over frequency (in my device), although it shows a dip somewhere near the 15m band.
 
B. The IRF510 can produce some nice power in the lower frequencies when increasing the PA supply voltage, but it comes at the price of a steep power drop at higher frequencies.
 
C. The bias does not seem to influence the efficiency of the finals at full power with RD16HHF1, since biasing at 250 and 500mA produces essentially the same output for the same DC power input. Assuming distortion reduces with higher bias, can we assume a higher bias (within limits) is preferable? Any risk of thermal runaway?
 
D. The board main current (which includes the current in the driving stages of the power amplifier) does not seem to change with frequency from 20m onwards. Is this because the gain is pretty constant? If so, most of the drop in power with increasing frequency seems to be in the IRF510s, supporting the results obtained with the RD16HHF1s.
 
E. With the current uBitx PA circuit the RD16HHF1 seems limited in output, although not having the proper test equipment I can't say where the limitation occurs.
 
F. When I increased the drive through VR1 I noticed that at around 40% for the lower frequencies and at around 60% for the top frequencies I get a compression effect and the output does not increase much more from there on. I left it at 60% and got a positive feedback on the voice quality on my first QSO on 40m. Therefore I assume that the compression/clipping is not significant at that level (but I can't measure the sprectral purity).
 
 
So since my target was around 10W on 10m and 10 to 15W on 40m minimum I can say I have reached my goal just by changing the finals to RD16HHF1s and supplying the board with 13.8VDC (below the 15.2/15V stated in the respective datasheets of the RD16HHF1 and TDA2822).
 
To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and source pins of the RD16s to match, then soldered in place.
 
It would be interesting to compare these results with others who performed the finals swap on the stock uBitx.
 
Next is the installation of the TPA2016 audio amplifier with I2C controllable AGC.

This is a lot of fun.
 
All the best,
 
73, John (VK2ETA)
 
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