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Re: larger uBitX
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Jack Purdum
Hi Mike: As I've said many times before, I'm a software guy and do not know enough about the ?BITX hardware to know what's what...but I will. I do know a little about the Si5351 as I've played around with the Adafruit breakout board. That chip might be the best option, but Al (AC8GY) is better qualified than I am to know the alternatives. Either way, this will be a fun project and a real learning experience. Thanks for the heads up! Jack, W8TEE From: K5ESS <k5ess.nothdurft@...> To: [email protected] Sent: Tuesday, December 5, 2017 7:45 PM Subject: Re: [BITX20] larger uBitX Jack, Craig, Don¡¯t overlook the fact that the ?Bitx requires three RF sources, VFO (converts RF input to 45 MHz.), a second LO (converts 45 MHz to 12 MHz.) and a BFO.? So a TFT/VFO based on one of the Analog Devices AD9xxx would still need some source of the other two needed frequencies.? If you¡¯re going to re-spin a new board why not go with the SI5351 that can supply all three frequencies? Mike K5ESS ?? ? From: [email protected] [mailto:[email protected]] On Behalf Of Jack Purdum via Groups.Io Sent: Tuesday, December 05, 2017 09:49 To: [email protected] Subject: Re: [BITX20] larger uBitX ? Mornin' Craig: ? My plan is to do the TFT/VFO display PCB specifically for the ?BITX. The two main changes will be a move to the AD9851 and the "full size" Mega 2560. This will make the board larger, but will lower the cost of the Mega and the '51 extends the usable frequency of the VFO. These two changes should also make it easier to acquire parts. Because of the size of the regular Mega, I will likely not worry about a small 2.4" display any more, but assume at least 2.8". I think 3.0" or larger would be better, as I want to put some band information on the display, too. ? My first work will be using the current B40 TFT display board. My cohort in crime, Al Peter (AC8GY), is in the middle of moving and will not be able to redo the board until early next year. In the meantime, my ?BITX changes will be using the current B40 PCB. My initial impression is that I can literally plug in the current PCB and it will work. I just need to figure out the header connections. Anyone who wants to switch to the AD9851 now can use the current board and omit D4 and D5 and jumper the 5V to the chip. The '50 falls off as you approach 30MHz, but the '51 has a much higher usable frequency. I haven't made the switch yet myself, so I don't know if I'll have to mess with the software but, even so, I don't see it as being a big deal. The really good news is that Ashhar has given us a gift where all those currently-idle memory resources on the Mega can be put to good use. ? My long, long run goal is to switch to a large touch screen display (e.g., 5"-7") controlled by a Teensy 3.6 and have an SDR with "panadapter" display that doesn't need to be tied to an external PC. I would also like to keep it well south of $200 as a price point. Alas, I'm not smart enough in digital signal processing and FFT's at the moment, but I've started the uphill trek on that learning curve. Anyone who wants to join me in that journey contact me off-group using my QRZ email. ? I can't tell you how excited all of this has me...we all need to express a HUGE thank you to Ashhar for not only making the effort to design and build the ?BITX, but also for keeping it open and reasonably-priced so we can all play with it...thanks again, Ashhar. ? Jack, W8TEE ? From: Craig Wadsworth <cwadsworth@...> To: [email protected] Sent: Tuesday, December 5, 2017 10:08 AM Subject: [BITX20] larger uBitX ? Hi Jerry & Ryan, ? Thanks for responding. ?I doubt I¡¯m alone in hoping to eventually tweak Jack Purdum¡¯s B40 TFT display for a uBitX but plan no other changes. ?The main goal is just to build a working transceiver that is not a kit. ?Is it fair to call such a build ¡®home-brewed¡¯ even if it is merely a larger-scale copy of Ashhar¡¯s circuit? ?It would of course have the added 45 MHz filter in his later schematic drawing with the four LPFs. ? ? After re-reading Ashhar¡¯s statement about rights to the board, I agree he has already said he does not plan to release the Gerber files. ?I¡¯m not sure how I might use them other than as a guide to parts placement on a larger board; a better approach would probably be to use Ashhar¡¯s photograph of his build shown at? ?as a reference (I have an 11x17-inch color print of that photo in a frame over my bench as motivation). ? ¡°¹ó°ù´Ç³¾:?Jerry Gaffke Date: Mon, 04 Dec 2017 21:05:33 CST? Sounds fun, are you planning any circuit mods? ?. . .? I don't recall gerbers of previous projects ever being made available. And not sure how they would help on a Manhatten build.¡± ? ?
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