Re: New sBitx development
Scott,
No. This is in addition to the upgrade carried out earlier.
And the details of the modifications carried out are on:
Thomas
Curious.? Is this the 5VDC regulator/PA heatsink change that has been on going for a while??
--
Support@...
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Re: New sBitx development
Curious. ?Is this the 5VDC regulator/PA heatsink change that has been on going for a while??
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Re: Sbitx #165 received today, thoughts.
Evan,
Yes I know that. I am not the one who asked the question!
Raj
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On 01/10/2022 11:34 AM, Evan Hand wrote:
Raj,
the relays do not have a diode across the coils. The I2C coil driver chip does.
73
Evan
AC9TU
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Re: sBitx PA blow - A fix
I haven't powered my sBit (#64) or installed the Pi, so I'll
watch & see what others say.
Gerry
Sent by the Thunderbird
On 2022-10-01 06:35, Ashhar Farhan
wrote:
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The PA blow out is happening due to the power
amplifier going into self-oscillations when it goes from
transmit back to receive. We think there is a fix for this that
involves making a cut in the PCB and soldering a wire.
Here is what is going on, briefly:
On receive the K9 relay and the U3 (electronic switch)
provide the path for the RF from the antenna to directly to
the input of the LPF (L16 to L21). Unfortunately, this is
also the input to the PA. At the end of transmission, when
the TX_LINE goes low. For a brief while, the drive and the
PA are switched on while the caps discharge and it has a
return path, setting up these huge oscillations.
The fix is to first power down the PA and then flip the
relays over. For this, we disconnect the Q10 that controls
the power to the PA from the TX_LINE and we use a fresh line
from the raspberry Pi (we call as TX_POWER) to switch the
power to the PA in sequence to avoid the oscillations.
All the details of the modifications are on:?
It just needs you to make a small cut in the PCB and
solder a wire.
- f?
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Re: sBitx PA blow - A fix
Great detective work.? ?This is the hard work of finding every little nook and cranny of a design.? ?Thank you for your work! Gordon Gibby KX4Z
On Sat, Oct 1, 2022 at 2:35 AM Ashhar Farhan < farhanbox@...> wrote: The PA blow out is happening due to the power amplifier going into self-oscillations when it goes from transmit back to receive. We think there is a fix for this that involves making a cut in the PCB and soldering a wire. Here is what is going on, briefly: On receive the K9 relay and the U3 (electronic switch) provide the path for the RF from the antenna to directly to the input of the LPF (L16 to L21). Unfortunately, this is also the input to the PA. At the end of transmission, when the TX_LINE goes low. For a brief while, the drive and the PA are switched on while the caps discharge and it has a return path, setting up these huge oscillations. The fix is to first power down the PA and then flip the relays over. For this, we disconnect the Q10 that controls the power to the PA from the TX_LINE and we use a fresh line from the raspberry Pi (we call as TX_POWER) to switch the power to the PA in sequence to avoid the oscillations. All the details of the modifications are on:? It just needs you to make a small cut in the PCB and solder a wire.
- f?
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Re: A Path Toward Adding a Noise Blanker and More?
#sBitx
And might I suggest an AM broadcast filter in the receive circuit. I put one in my ubitx v4 and it helped ALOT. Yes noise blanker and S meter would be nice?
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Re: My new sBitx is RF deaf
#sBitx
what board was bad ? My Sbitx # 0128 is deaf then can hear then goes crazy even on a dummy load
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Re: Daylight Radio: Crystals?
Hello Steve,
that is the approach that a lot of us are using. by building it on boards one block at a time, it seems to make trouble shooting and testing of sections much easier. Good luck on your project.
Alan w7aln
On Sat, Oct 1, 2022, 12:01 AM Stephen Farthing < squirrox@...> wrote: I¡¯m also gathering daylight radio parts. I¡¯m minded to build as a set of modules each with their own PCB, partly because I¡¯ve promised to learn KiCAD and this seems a good place?to start. I¡¯ve a 3D printer at home in the U.K. and, if the designs are available, I¡¯d be happy to print parts for the permeability tuner for fellow builders. I¡¯m not sure how practical is is to ship things outside the U.K. though.?
73s Steve G0XAR On Sat, 1 Oct 2022 at 05:44, Ashhar Farhan < farhanbox@...> wrote: Mark, It might be better to move to 4.915 MHz to avoid the WWV breakthrough. Almost any crystal in HC/49U will do. It is best to measure the motional parameters not required. - f
I'm gathering parts to build a Daylight Radio. What are the critical specs for the 5 MHz crystals? Capacitance, etc? How critical?
Thanks & 73....?????? Mark???? AA7TA
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Re: Daylight Radio: Crystals?
I¡¯m also gathering daylight radio parts. I¡¯m minded to build as a set of modules each with their own PCB, partly because I¡¯ve promised to learn KiCAD and this seems a good place?to start. I¡¯ve a 3D printer at home in the U.K. and, if the designs are available, I¡¯d be happy to print parts for the permeability tuner for fellow builders. I¡¯m not sure how practical is is to ship things outside the U.K. though.?
73s Steve G0XAR
On Sat, 1 Oct 2022 at 05:44, Ashhar Farhan < farhanbox@...> wrote: Mark, It might be better to move to 4.915 MHz to avoid the WWV breakthrough. Almost any crystal in HC/49U will do. It is best to measure the motional parameters not required. - f
I'm gathering parts to build a Daylight Radio. What are the critical specs for the 5 MHz crystals? Capacitance, etc? How critical?
Thanks & 73....?????? Mark???? AA7TA
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I have not blown anything, YET ( fingers crossed ) I cleaned all the powder coat from the countersunk holes in the case to make sure all of the case was grounded including the Pi and screen. After doing that and putting the radio back together it did nor receive at all. It would transmit fine but waterfall was blank. I gave up for a while and a few hours later I decided to turn it back on and it recieved just fine for about 30 minutes then started the excess static and crackling with the waterfall going yellow to red even after switching to a dummy load. I'm lost, all i can think is its software??
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The PA blow out is happening due to the power amplifier going into self-oscillations when it goes from transmit back to receive. We think there is a fix for this that involves making a cut in the PCB and soldering a wire. Here is what is going on, briefly: On receive the K9 relay and the U3 (electronic switch) provide the path for the RF from the antenna to directly to the input of the LPF (L16 to L21). Unfortunately, this is also the input to the PA. At the end of transmission, when the TX_LINE goes low. For a brief while, the drive and the PA are switched on while the caps discharge and it has a return path, setting up these huge oscillations. The fix is to first power down the PA and then flip the relays over. For this, we disconnect the Q10 that controls the power to the PA from the TX_LINE and we use a fresh line from the raspberry Pi (we call as TX_POWER) to switch the power to the PA in sequence to avoid the oscillations. All the details of the modifications are on:? It just needs you to make a small cut in the PCB and solder a wire.
- f?
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Re: Sbitx #165 received today, thoughts.
Raj,
the relays do not have a diode across the coils. The I2C coil driver chip does.?
73
Evan
AC9TU
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Hi Aaron As an alternative, try ¡°mebrew¡± instead of pads or square, to create insulated islands on your blank pcb.
- nibbled blank double sided pcb
- 10M¦¸ SMD resistor
- 2.2pF SMD capacitor
- modified jewel screwdriver to cut a circular pattern on blank pcb
- ¡your imagination
I prefer pcb nibbler and jewel screwdrivers, that give me advanced result with that simple technique. Here is an example of a 40MHz crystal filter with 5032 SMD crystal 73, Pascal
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Re: Sbitx #165 received today, thoughts.
I dont think these have a diode across the coil. Enclosed is a data sheet.
Raj
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On 30/09/2022 11:49 PM, ajparent1/kb1gmx wrote: Raj,
That C14 tests suggest that K9 relay is either in NC state at the wrong times
along with U3 or enough leakage though to make a big high power oscillator.
Do we know if any of the relay coils have diodes across them??
Allison
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Re: Daylight Radio: Crystals?
Mark, It might be better to move to 4.915 MHz to avoid the WWV breakthrough. Almost any crystal in HC/49U will do. It is best to measure the motional parameters not required. - f
I'm gathering parts to build a Daylight Radio. What are the critical specs for the 5 MHz crystals? Capacitance, etc? How critical?
Thanks & 73....?????? Mark???? AA7TA
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Re: uBITX v6 Standalone Signal Analyzer (I2C Type Signal-Meter) for uBITX #2 Nextion LCD
#smeter
#ubitx-v6
It¡¯s one. Part of the confusion here is that Dr Lee had created a sensor that would just plug into the Raduino. So he is assuming that folks might have done that first before now needs to disable it when they go to the standalone. ?
btw: there is a more advance version of that standalone code. Best to get the basic working and then try this other one. See?
never had a chance to try it myself but Dr Lee seemed to think it was an improvement on his work.?
73
Mark
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Daylight Radio: Crystals?
I'm gathering parts to build a Daylight Radio. What are the critical specs for the 5 MHz crystals? Capacitance, etc? How critical?
Thanks & 73....?????? Mark???? AA7TA
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In my development version you can drag the center of the display in the frequency area below the spectrum display.
To try it:
cd /home/pi
git clone?
cd sbitx-k3ng
git pull
git checkout?2022.09.15
./build sbitx
./sbitx
73 Goody
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Is there a way to change the center of the spectrum display? It seems to be centered on the (suppressed) carrier frequency, which means that you see the spectrum for both sidebands. It would be nice if there was a way to have it centered on the center of the filter range.
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Re: Gtk-WARNING: cannot open display (./sbitx)
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Re: Gtk-WARNING: cannot open display (./sbitx)
here¡¯s a photo of the DISPLAY variable after I defined it.
¡ªkeep in mind a week ago I used putty without any trouble and sbitx ran perfectly when started either by clicking on a sbitx icon, cmd line ./sbitx on the sBitx touchscreen, or using putty ?./sbitx
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Raj vu2zap
Butch
John Terrell, N6LN