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Interesting QST article


Bob Lunsford
 

The December issue of QST has an interesting article about using an Arduino in a simple transmitter (Page 30).

It is hardly as sophisticated as the use of the technology here but it may be of interest to see what someone else is doing with the technology.

Bob — KK5R


Bob Benedict, KD8CGH
 

If you're interested in a truly amazing use of an Arduino in an SDR check out the uSDX transceiver
https://groups.io/g/ucx
--
  73
    Bob  KD8CGH


Bob Lunsford
 

That is indeed an interesting concept. I wonder if it would pass an FCC certification, though. A lowpass filter is needed, no doubt, and I don't see one. Nor AGC, etc., etc. But it is indeed interesting.

Bob — KK5R

Schematic of the uSDX...

Inline image


On Tuesday, November 17, 2020, 6:46:58 AM EST, Bob Benedict, KD8CGH <rkayakr@...> wrote:


If you're interested in a truly amazing use of an Arduino in an SDR check out the uSDX transceiver
https://groups.io/g/ucx
--
  73
    Bob  KD8CGH


Jack, W8TEE
 

Hi Bob:

I just joined the group a few days ago and look forward to working on it. I've ordered a µSDR kit, but hope to modify it for a TFT display and a Teensy T4 processor. I'm not very adept at EE stuff, but not too bad on the firmware. I'm looking forward to it.

Jack, W8TEE

On Tuesday, November 17, 2020, 7:26:23 AM EST, Bob Lunsford via groups.io <nocrud222@...> wrote:


That is indeed an interesting concept. I wonder if it would pass an FCC certification, though. A lowpass filter is needed, no doubt, and I don't see one. Nor AGC, etc., etc. But it is indeed interesting.

Bob — KK5R

Schematic of the uSDX...

Inline image


On Tuesday, November 17, 2020, 6:46:58 AM EST, Bob Benedict, KD8CGH <rkayakr@...> wrote:


If you're interested in a truly amazing use of an Arduino in an SDR check out the uSDX transceiver
https://groups.io/g/ucx
--
  73
    Bob  KD8CGH

--
Jack, W8TEE


Bob Lunsford
 

Jack, you have very nice images on your qrz.com webpage. Very nice...and impressive.

I'm sure you will be adding to this forum considering your background in education and ham radio. I look forward to your input.

Bob — KK5R

On Tuesday, November 17, 2020, 9:05:41 AM EST, Jack, W8TEE via groups.io <jjpurdum@...> wrote:


Hi Bob:

I just joined the group a few days ago and look forward to working on it. I've ordered a µSDR kit, but hope to modify it for a TFT display and a Teensy T4 processor. I'm not very adept at EE stuff, but not too bad on the firmware. I'm looking forward to it.

Jack, W8TEE

On Tuesday, November 17, 2020, 7:26:23 AM EST, Bob Lunsford via groups.io <nocrud222@...> wrote:


That is indeed an interesting concept. I wonder if it would pass an FCC certification, though. A lowpass filter is needed, no doubt, and I don't see one. Nor AGC, etc., etc. But it is indeed interesting.

Bob — KK5R

Schematic of the uSDX...

Inline image


On Tuesday, November 17, 2020, 6:46:58 AM EST, Bob Benedict, KD8CGH <rkayakr@...> wrote:


If you're interested in a truly amazing use of an Arduino in an SDR check out the uSDX transceiver
https://groups.io/g/ucx
--
  73
    Bob  KD8CGH

--
Jack, W8TEE


Jack, W8TEE
 

Thanks, Bob! I'm really looking forward to it.

Jack, W8TEE

On Tuesday, November 17, 2020, 9:20:20 AM EST, Bob Lunsford via groups.io <nocrud222@...> wrote:


Jack, you have very nice images on your qrz.com webpage. Very nice...and impressive.

I'm sure you will be adding to this forum considering your background in education and ham radio. I look forward to your input.

Bob — KK5R

On Tuesday, November 17, 2020, 9:05:41 AM EST, Jack, W8TEE via groups.io <jjpurdum@...> wrote:


Hi Bob:

I just joined the group a few days ago and look forward to working on it. I've ordered a µSDR kit, but hope to modify it for a TFT display and a Teensy T4 processor. I'm not very adept at EE stuff, but not too bad on the firmware. I'm looking forward to it.

Jack, W8TEE

On Tuesday, November 17, 2020, 7:26:23 AM EST, Bob Lunsford via groups.io <nocrud222@...> wrote:


That is indeed an interesting concept. I wonder if it would pass an FCC certification, though. A lowpass filter is needed, no doubt, and I don't see one. Nor AGC, etc., etc. But it is indeed interesting.

Bob — KK5R

Schematic of the uSDX...

Inline image


On Tuesday, November 17, 2020, 6:46:58 AM EST, Bob Benedict, KD8CGH <rkayakr@...> wrote:


If you're interested in a truly amazing use of an Arduino in an SDR check out the uSDX transceiver
https://groups.io/g/ucx
--
  73
    Bob  KD8CGH

--
Jack, W8TEE

--
Jack, W8TEE


Jerry Gaffke
 

Bob's LPF is in the lower right corner of the uSDX schematic.
Jerry, KE7ER


On Tue, Nov 17, 2020 at 04:26 AM, Bob Lunsford wrote:
That is indeed an interesting concept. I wonder if it would pass an FCC certification, though. A lowpass filter is needed, no doubt, and I don't see one. Nor AGC, etc., etc. But it is indeed interesting.
 


Jerry Gaffke
 

Make that lower left.
Time for some coffee.


On Tue, Nov 17, 2020 at 06:50 AM, Jerry Gaffke wrote:
Bob's LPF is in the lower right corner of the uSDX schematic.
Jerry, KE7ER


Bob Lunsford
 

I saw "one" LPF in the lower left-hand corner of the schemetic and some data on another page for other LPF's. But the uBITX is a complete rig for ham radio. I suspect that the radio would be a great receiver, though. (I still prefer the V6)...

Bob — KK5R

On Tuesday, November 17, 2020, 9:51:03 AM EST, Jerry Gaffke via groups.io <jgaffke@...> wrote:


Bob's LPF is in the lower right corner of the uSDX schematic.
Jerry, KE7ER

On Tue, Nov 17, 2020 at 04:26 AM, Bob Lunsford wrote:
That is indeed an interesting concept. I wonder if it would pass an FCC certification, though. A lowpass filter is needed, no doubt, and I don't see one. Nor AGC, etc., etc. But it is indeed interesting.
 


Bob Lunsford
 

Gotcha ... belatedly.

Bob — KK5R

On Tuesday, November 17, 2020, 9:52:36 AM EST, Jerry Gaffke via groups.io <jgaffke@...> wrote:


Make that lower left.
Time for some coffee.

On Tue, Nov 17, 2020 at 06:50 AM, Jerry Gaffke wrote:
Bob's LPF is in the lower right corner of the uSDX schematic.
Jerry, KE7ER


Tom, wb6b
 

On Tue, Nov 17, 2020 at 03:46 AM, Bob Benedict, KD8CGH wrote:
If you're interested in a truly amazing use of an Arduino in an SDR check out the uSDX transceiver
This does look very amazing. I'll read and learn more about this design. Especially interested to see how well the ATMega328P handles what would seem like quite a bit of digital audio signal processing. Also interested in the class E TX operation for SSB, I've seen that subject discussed on this group in the past.

Tom, wb6b


Curt
 

The whole point of this project is not to compete with any other rig, but its a creative opportunity for tinkerers. 

Okay remember many of our partners on this list are outside of NA and don't likely get QST, but may be members of their radio society.  So here are the highlights:

- decades ago QST published a 2 transistor, xtal controlled transmitter built on a tuna can.  it became a classic
- article describes a similar simple transmitter connected to an Si5351a PLL and display via Nano
- modular design using bought items for all but the PA and LPF board, nice well written article
- microcode provided
- I am a bit surprised they chose an IRF510 and not a BS170 for the PA, but I wonder if it has more gain that may be needed here (okay I need to read the article)

73 Curt


Shirley Dulcey KE1L
 

The uSDX, as originally designed, is a single band radio. It only needs one LPF.

One of the circuit board kits separates the LPF and a few other nearby components onto a separate PC board that plugs in. That allows it to be moved to another band by replacing the board with one for another band.

On Tue, Nov 17, 2020 at 5:21 PM Curt via groups.io <wb8yyy=yahoo.com@groups.io> wrote:
The whole point of this project is not to compete with any other rig, but its a creative opportunity for tinkerers. 

Okay remember many of our partners on this list are outside of NA and don't likely get QST, but may be members of their radio society.  So here are the highlights:

- decades ago QST published a 2 transistor, xtal controlled transmitter built on a tuna can.  it became a classic
- article describes a similar simple transmitter connected to an Si5351a PLL and display via Nano
- modular design using bought items for all but the PA and LPF board, nice well written article
- microcode provided
- I am a bit surprised they chose an IRF510 and not a BS170 for the PA, but I wonder if it has more gain that may be needed here (okay I need to read the article)

73 Curt


Tom, wb6b
 

On Tue, Nov 17, 2020 at 02:49 PM, Shirley Dulcey KE1L wrote:
That allows it to be moved to another band by replacing the board with one for another band.
At some point I wonder if it would be possible to build QRP to moderate power TX stages at low enough cost, that rather than using relays or other filter switching methods for a multi band transceiver, you could just have a separate final RF power transistor and filter for each band. Just turn on the output section for the band you are interested in. Hopefully the filter sections could be designed so they could just be common connected together for the antenna connection. 

Tom, wb6b


Bill Cromwell
 

Hi,

It has been done over and over again from the time of earliest vacuum tube gear right up to recent days. It is a viable concept. See how you can use plug-in band changes on the newest gear:)

73,

Bill KU8H

bark less - wag more

On 11/17/20 6:41 PM, Tom, wb6b wrote:
On Tue, Nov 17, 2020 at 02:49 PM, Shirley Dulcey KE1L wrote:
That allows it to be moved to another band by replacing the board
with one for another band.
At some point I wonder if it would be possible to build QRP to moderate power TX stages at low enough cost, that rather than using relays or other filter switching methods for a multi band transceiver, you could just have a separate final RF power transistor and filter for each band. Just turn on the output section for the band you are interested in. Hopefully the filter sections could be designed so they could just be common connected together for the antenna connection.
Tom, wb6b


Bob Benedict, KD8CGH
 

The uSDX is a development effort that has several evolving designs, it's not a single product like the uBITX V6. One cool aspect of it is that it uses a highly efficient class E amp not only for CW, but for other modes too. It pulls off this wizardry by pulse width modulating the power to the amp. It's a uses direct conversion SDR receiver with the rest of the signal processing done computationally. The amazing thing is that all of this, including A/D and D/A, is all done by an Arduino so there is a very low discrete parts count.
It started single band as a modification of QRP Labs QCX class E amp CW transceiver. The two main design streams now have multiband filter boards. 
Check out the uSDX group.io WIKI for an overview.

I built a uBITX V4, a WB2CBA uSDX and I'm slowly building a DL2MAN version uSDX (I'm not so good with SMD). In my opinion, compared to the uBITX, the uSDX has more features like AGC and variable filters. It's better at CW since it's QSK and has filters you can narrow, but the SSB transmission is not as good. The uSDX firmware is evolving rapidly, like in the early uBITX days,  so we'll see how it progresses.

BTW Farahan often participates in uSDX discussions. I wouldn't be surprised to see a new transceiver from HF Signals.

--
  73
    Bob  KD8CGH


Kelly Jack
 

The new QCX mini in the pipeline from QRPLabs is proposed to come with some simple circuit modifications built in to make it easy to turn the QCX mini into a ucx (there are some user supplied parts required).

A much simpler way to try this circuit than the "from scratch" approach if that is preferred. 

73
Simon
VK3ELH 


Bob Benedict, KD8CGH
 

Simon

  Full circle. This all started with people modifying a QCX. It's great to see Hans supporting the hardware mod. Although, as he carefully notes, you will need firmware and support from the group.

You can also buy uSDX boards and parts from https://shop.offline.systems/.
--
  73
    Bob  KD8CGH


Dave AA6RE
 

Link to group is:



Dave, AA6RE


On Wed, Nov 18, 2020 at 3:15 AM Bob Benedict, KD8CGH <rkayakr@...> wrote:
The uSDX is a development effort that has several evolving designs, it's not a single product like the uBITX V6. One cool aspect of it is that it uses a highly efficient class E amp not only for CW, but for other modes too. It pulls off this wizardry by pulse width modulating the power to the amp. It's a uses direct conversion SDR receiver with the rest of the signal processing done computationally. The amazing thing is that all of this, including A/D and D/A, is all done by an Arduino so there is a very low discrete parts count.
It started single band as a modification of QRP Labs QCX class E amp CW transceiver. The two main design streams now have multiband filter boards. 
Check out the uSDX group.io WIKI for an overview.

I built a uBITX V4, a WB2CBA uSDX and I'm slowly building a DL2MAN version uSDX (I'm not so good with SMD). In my opinion, compared to the uBITX, the uSDX has more features like AGC and variable filters. It's better at CW since it's QSK and has filters you can narrow, but the SSB transmission is not as good. The uSDX firmware is evolving rapidly, like in the early uBITX days,  so we'll see how it progresses.

BTW Farahan often participates in uSDX discussions. I wouldn't be surprised to see a new transceiver from HF Signals.

--
  73
    Bob  KD8CGH