Re: uBITX full design

Lawrence Galea

I have the μbitx 3 and was thinking aloud about separate filters for each band
Thanks and regards

On Tue, Sep 24, 2019 at 4:10 AM Ashhar Farhan <farhanbox@...> wrote:
If you are thinking of a bank if band pass filters, then you dont need the complexity and performance hit of the double conversion  ubitx. Go for single conversion like the bitx40 or bitx20. The performance is kuch superior. 

On Tue 24 Sep, 2019, 1:29 AM Lawrence Galea, <9h1avlaw@...> wrote:
Thanks all for your feedback

On Mon, Sep 23, 2019 at 8:35 PM Jerry Gaffke via Groups.Io <> wrote:
If building a new board for external low pass filters, 
could spend an extra $0.50 on a processor to interpret serial commands from the Raduino.
If wires kept short could use the i2c bus, pin count impact on the Raduino is a minus 3
since this frees up the TXA,TXB,TXC pins.
And perhaps include a tandem match style SWR detector out there, 
communicates back to the Raduino over that same serial bus.

None of the communications out to this LPF board need speed,
this LPF board is a better choice for i2c than the display.

Not that I feel any real need for 10 LPF's.  
The 4 we have on the uBitx adequately cover the WARC bands.
Putting the corner frequencies closer to the top edge of each band
would allow better attenuation of harmonics, but in some jurisdictions at least
the v5 uBitx meets regulatory requirements.
Sufficient in my book for a QRP rig.
Actually, 20/40/80m is sufficient in my book for an $129 SSB transceiver.

There were several reports in this forum of Raduino clones being built
that had more IO pins.  Moving to an Arm blue pill would seem ideal
for a Raduino upgrade.  W3JDR got most of the way there:

I'd much prefer something like that for getting extra pins for tasks where
execution time is a consideration, serial access over i2c is awfully slow.

If doing a Raduino clone, address these issues of the current Raduino:
    No reverse polarity protection for the 12v supply
    No protection for the IO pins that go off board, please add 100 or 1000 ohm series resistors.
    Avoid having Raduino oscillators create birdies in the receiver
    Perhaps improve si5351 drive power to 7dBm,  have optional second si5351 to avoid crosstalk?
Might be a good project for some engineering student.
Jonathan, you still out there?

Jerry, KE7ER

On Mon, Sep 23, 2019 at 10:05 AM, ajparent1/KB1GMX wrote:
On Mon, Sep 23, 2019 at 08:34 AM, Lawrence Galea wrote:
Did you ever think of making available a raduino with switching for every one of the 10 HF bands so that one could use external BPFs instead of the ones on the board or perhaps a program for those who want to change the original software to do so?
Or is there any programmer on this list who is willing to do it?
Thanks to all
Likely no as its too great a change to the Raduino and the ubitx.

The existing version is at best good for 8 bands if one uses TXA,TXB,TXC as 
a binary band select along with an external decoder chip like 74138 (3-8 decode).

If one is willing a ground up build and a improved raduino-like approach would be doable.
The trick with the Nano is using a I2C display to free up pins and readjusting what pins are
used where.


Join to automatically receive all group messages.