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Re: Tx frequency selection for FT8 on BITX40 running Allard's sketch
#bitx40
Tim Gorman
I believe you are transmitting an audio tone through a SSB transmitter.
If your freq dial is set to 7.074.000 and you are sending a 1khz audio tone you will actually be transmitting on 7.075.000 (i.e. 7074000 + 1000). tim ab0wr On Thu, 19 Apr 2018 06:33:56 -0700 "Doug W" <dougwilner@...> wrote: On Thu, Apr 19, 2018 at 03:09 am, Vic WA4THR wrote:Thank you for the reply but your answer does not address the
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Franken-uBitx (no Raduino, and apologies to Mary Shelley :-)
Mark Pilant
Never one to take the easy road, I thought I'd share my progress so far
with building up my uBitx. I call it my "Franken-uBitx" because it is made up from a lot of different parts I had laying around. :-) :-) So far, my Franken-uBitx consists of the following: 1) An unchanged uBitx main board (no Raduino used) 2) An Adafruit 2050 3.5 inch (320 x 480) TFT touchscreen 3) An Adafruit 2045 Si5351 Clock Generator Breakout board 4) Meduino Mega2560 Pro Mini board as the major assemblies. The software started out as the TFT_uBitx sketch by VU2SPF and VE1BWV. I then made various changes to the code: 1) To more easily support the Meduino board (2 row pin headers instead of single pins; but the board is about the size of an Uno) 2) Support the TFT display 3) Support the encoder Some of the other changes I have made (or am planing to make) are: 1) Added a socket for the TDA2822 chip 2) Separate fuses for the uBitx board and PA 3) Separate On/Off switch (and power on LED) and traditional (shaft) sized volume control 4) Separate 5V regulator (with plus and minus power buss) to power the Meduino, display, and Si5351 boards All of this in a Hammond box I had around. Right now, the sketch works with a nice touch screen interface as well as all the clock frequencies generated. The next major step is to wire up the 5V regulator and power buss. Then it is really nothing more than connecting everything up. Then some final testing before getting on the air. In addition, I'll be documenting all of this (with pictures) for anyone else to borrow from :-) Oh yes, I also have another uBitx I plan to leave pretty much stock except for changing the 2 line display to a 4 line display. That way I'll have an easy way to do A / B comparisons. Hopefully my project will add to the pool of things for others to try :-P 73 - Mark N1VQW
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Re: Replacement for the blown tda2822
riparry@...
Hello Dex, There doesn't seem to be many ZLs building the uBitx so wonder if we could link up? I am in Christchurch 03 3389021
Cheers Ron ZL3VX
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Re: show your mic
Ashhar Farhan
What do you know! Mine is uglier than yours.
On Thu, 19 Apr 2018, 22:53 Bill KC5SB, <blmerideth@...> wrote: Here's mine. I made it from an old 9 volt flashlight.
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Re: proof readers needed for KD8CEC firmware manual
Rod
ill give it a go.. vince n2aie
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Re: uBITX shipping time
hotrod541@...
Ordered on March 14th and was delivered on 4-19-2018, 3 days after being notified by DHL. Now if the case would come I will be happy person. I need to download the construction manual, if I can find it. What software is best to install?
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Re: Transmitter Mods
Jerry Gaffke
The parallel resonance helps us to a point, though an ideal inductor would generally be better.
toggle quoted messageShow quoted text
For example, if the inductor is self resonant at 14mhz, we'd see much more power out on 20m than we see on 10m. I'd prefer to keep gain vs freq somewhat controlled and predicatable. The caps are easier to add, easier to obtain, have a higher self resonance: https://electronics.stackexchange.com/questions/193608/self-resonance-frequency-for-mlcc-capacitor Maybe add 220pF caps across all six of the 22 ohm emitter resistors, and forget the inductor? Then add a variable cap somewhere around Q90 that can be tweaked to give the flattest response, that setting may vary given your particular 2n3904 transistor characteristics. But the inductor in series with the negative feedback is a good idea. If this can all be done with just 3 extra components and get good enough results across the different uBitx's out there, I'm fine with that. One other issue: As Henning notes in post 45035, the chokes L8 and L9 are best wound on a single core: See the discussion below figure 4 on this webpage, where he discusses how the bifiliar approach works, though he does not discuss the individual choke solution: http://ludens.cl/Electron/mosfetamps/amps.html I was seeing significantly worse results in how the uBitx final worked compared to the WA2EBY final in my LTSpice simulation, could be due to these chokes. https://groups.io/g/BITX20/topic/9615903 I may have to play with that further, not obvious to me how or if the individual chokes at L8, L9 would impact the results.. Jerry, KE7ER
On Thu, Apr 19, 2018 at 11:00 am, Jerry Gaffke wrote:
Good question.
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Re: ubitx is available for $109, there are a3 catches
M Garza <mgarza896@...>
You will receive a message from PayPal with a tracking number when it ships. They are running 4 to 6 weeks behind. Marco - KG5PRT
On Thu, Apr 19, 2018, 8:14 AM RMV <W8RMV@...> wrote: Ashhar Farhan,
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Re: Transmitter Mods
Gordon Gibby <ggibby@...>
Aha!!!
toggle quoted messageShow quoted text
Thanks. Didn’t realize it was parallel.
Much appreciated. Learn something every day!
Gordon
On Apr 19, 2018, at 14:00, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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Re: Transmitter Mods
Jerry Gaffke
Good question.
toggle quoted messageShow quoted text
It's a parallel resonance: https://www.everythingrf.com/community/what-is-self-resonant-frequency
On Thu, Apr 19, 2018 at 10:55 am, Gordon Gibby wrote: How is a series resonance 30,000 ohms?
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Re: Transmitter Mods
Gordon Gibby <ggibby@...>
How is a series resonance 30,000 ohms?
toggle quoted messageShow quoted text
I’m kind of dumb, but I thought at series resonance , reactive components cancel and all that is left is the tiny ohmic resistance of the wire.
What am I missing?
Thanks
Gordon
On Apr 19, 2018, at 13:22, Howard Fidel <sonic1@...> wrote:
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Re: ubitx is available for $109, there are a3 catches
K5ESS
No
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of RMV
Ashhar Farhan,
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Re: show your mic
Bill KC5SB
Here's mine. I made it from an old 9 volt flashlight.
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Re: Transmitter Mods
Howard Fidel
Gordon: Very high, about 30 K. It actually helps us. Howard
On 4/19/2018 1:03 PM, Gordon Gibby wrote:
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Re: Transmitter Mods
Howard Fidel
That is a good question. In our
application, the impedance is still high, it just becomes more
capacitive then inductive. If you look at the impedance plot, the
resonance is about 20 MHz, but the reactance at 30 MHz is still
2000 ohms, so the gain goes up. On the 15 meter band, it looks
like 30K ohms, so the amp runs open loop. The bottom line is that the design is not that robust to begin with, and what I have made is a patch. I would never have designed the signal path myself this way. I would have use an opamp to drive the transformer to replace everything from C80 to T10. The fix works, and has been validated by others. It would be smaller, probably not cheaper, but robust. Howard
On 4/19/2018 12:59 PM, ohwenzelph via Groups.Io wrote:
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Re: Tx frequency selection for FT8 on BITX40 running Allard's sketch
#bitx40
Hi Doug, Agreed. I operate remotely from the Yukon as VY1AAA a lot... when on FT8, it generates Big pileups. Those people who understand how to use split in FT8 get through faster. Technique is still important. I’m excited to try FT8 on the uBitX (which arrives Friday) from the home QTH in NH. 10w + FT8 has provided many DXCC in short order. Gerry W1VE
On Thu, Apr 19, 2018 at 11:32 AM Doug W <dougwilner@...> wrote: Thanks Gerry. Interestingly enough I did some searching on the topic of operating FT8 in split mode. Turns out it is a hotly contested topic in certain circles with very strong opinions on both sides. I think it is time for me to shift from theoretical to practical and leave the details to the guy with the medal from Sweden.
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Re: Transmitter Mods
Gordon Gibby <ggibby@...>
I found some on digikey with a self resonaance 40 Mhz or higher....
probably does matter. At the self resonant point the series impeane will be very low....
From: BITX20@groups.io <BITX20@groups.io> on behalf of ohwenzelph via Groups.Io <Ohwenzelph@...>
Sent: Thursday, April 19, 2018 12:59 PM To: bitx20@groups.io Subject: Re: [BITX20] Transmitter Mods does it matter that most 27uH inductors seem to have a self resonant frequency below 28MHz?
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Re: UbitX I2C GPIO Breakouts?
Understood. I’m wanting to put transverters in my ubitx; would love to control the I/O switching, as well as have the display show the transverted frequency. So, these would not be signals that needed to be switched rapidly. I would not use it to key CW, but I might use these I/Os for a keying sequencer. Gerry, W1VE
On Thu, Apr 19, 2018 at 12:45 PM Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote: Could work fine.
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Re: Transmitter Mods
ohwenzelph
does it matter that most 27uH inductors seem to have a self resonant frequency below 28MHz?
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Re: anybody tried softrock and hdsdr with Ubitx?
Paul Schumacher
Has anyone tried a softrock and hdsdr with Ubitx to get the spectrum and waterfall display? (or something similar?) If so, can you please describe how to go about doing it? thanks, Paul K0ZYV http://www.phonestack.com/farhan/bitx.html The original BITX Group Home Contact Group Owner Terms Of Service Unsubscribe From This Group _._,_._,_
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