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- BITX20
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Re: ?BITX Disable TC (use for CW training)
Yes. The firmware is backwards compatible. - f On Sat, 2 Jun 2018, 19:12 Hans Stoll, <tool4fish@...> wrote: On Sat, Jun? 2, 2018 at 06:41 am, Hans Stoll wrote: |
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Re: uBITX physical comm port - newbie question
Tom Francis
¿ªÔÆÌåÓýThanks for the quick reply - I really appreciate it.I do some QRP building and experiment a little, but I've never gotten into the micro controller scene much at all other than reading up on it.? 50 some years of playing radio I'm still something of a Luddite. I will do what you suggest - looks like fun. Thanks again. Best regards, Tom, W1TEF On 6/2/2018 1:55 PM, Ralph Mowery
wrote:
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LCD Interface Question: Parallel or I2C?
#bitx20
#bitx40help
#firmware
As hams have hacked or modified their uBITX transceivers, some have moved to a 4-line LCD controlled via an I2C connection.? The electrical connections with a 2x16 or a 4x20 LCD look the same, so why the need for the I2C interface?? It would seem easier to simply change the display addresses and use the standard interface.? Could someone explain to this newcomer why I2C offers advantages or if some incompatibility exists between the display types.? Thanks.?
-- Jon Titus, KZ1G Herriman, UT USA |
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Re: uBITX physical comm port - newbie question
¿ªÔÆÌåÓýThank you very much.? Appreciate it.Best regards, Tom - W1TEF On 6/2/2018 1:47 PM, Ralph Mowery
wrote:
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Re: RF power chain mods and improvements..
On Sat, Jun 2, 2018 at 09:48 am, Arv Evans wrote:
Yep and everyone we to adding a preamp or compressor.? What they are trying to fix is the output of the 45mhz mixer is very low and even at 80m the power amp if run that way puts out about 10W.? Move up to 40M or 20M where the power amp has less gain and people drive the audio harder and you get 7W.? NOt a problem yet as the low pass filters are adequate. At 21mhz the game is worse, less gain and less power and more audio gets used and now the filters are wide open.... FYI the output of that mixer is clean at -19dbm after the 30mhz filter.? That means to hit 10W you need 59DB of gain.? The base amp on 80M maybe does 62db wide open. at 40M that drops under 55....? and at 10M your stock amp chain gain is maybe at 45db or about 50 (maybe 100) milliwatts so if your seeing more its audio push to make up for it.? How much push at -11dbm? the spur is less than 30db down (V bad!) and your getting 1.7 to 2W.?? With a highly modded TX we get to 3w, turn up the mic gain and 10W and that spur at 16mhz is now about 20-50mW!? That is the problem!?? Also audio gain controls would be turned up anyway, its just one more mis-adjustment. Of ten radios built by me and on the air only one has a mic gain, its there because the hole was there first in a reused box. Once set it has never moved.?? Allison |
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Re: Power supply question
¿ªÔÆÌåÓýThe LM1085-12 has a dropout voltage of 1.3v typ; 1.5v max.?? The lm1117ADJ likewise has a low dropout voltage but would require a couple more parts since that part doesn¡¯t come in a fixed 12v version. Mike K5ESS ? From: [email protected] [mailto:[email protected]] On Behalf Of Bo Barry ? If I recall correctly the 3 terminal regulators definitely need a minimum of 3 volts difference between input and output. |
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Re: uBITX physical comm port - newbie question
Before playing too much with it, you can get just the Arduino processor and play with it.? They are only about $ 2.50 from China off ebay if you don't mind waiting 3 or so weeks.? This is what I bought a while back to do some playing.? There are 5 of them for about $ 12, but you can find single lots of them. Notice the silver thing on the left.? That is the USB connector you are looking for.? They can be powered by just the usb connector plugged into the computer if you just want to play with the programming of them.? Same with the ubitx.? The display will light up and you can program it through that connector, but the rest of the ubitx will not be powered.?? de ku4pt. On Sat, Jun 2, 2018 at 1:19 PM, <ubitx@...> wrote: First, thanks for letting me join - appreciate it.? The question I'm asking is pretty simple, but I have no experience with this at all.? I've put my uBITX together and it works - really cool too I might add. I looked around, but I can't find any installation instruction or guides with respect to putting the physical USB Comm port connector into the uBITX. Any help with this would be greatly appreciated.? Thanks for you patience with a newbie.? Tom, W1TEF |
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Re: uBITX physical comm port - newbie question
With the display facing you, turn it so you cal look into the right side of the display between it and the board behind it.? You will see a small USB connector facing you . .? Forgot what it is called , maybe a mini USB.? Any of the usb cables that fit will work if you are sure you have a data cable.? Some cable are just for charging the batteries of a cell phone and only use 2 of the 4 wires in the USB cable. You will need a program to see anything out of this port on the computer.? Go here: for free software .? Arduino 1.8.5 seems to be the latest Windows software for it. This is the home page for lots of info on the Arduino processor. 73 de ku4pt On Sat, Jun 2, 2018 at 1:19 PM, <ubitx@...> wrote: First, thanks for letting me join - appreciate it.? The question I'm asking is pretty simple, but I have no experience with this at all.? I've put my uBITX together and it works - really cool too I might add. I looked around, but I can't find any installation instruction or guides with respect to putting the physical USB Comm port connector into the uBITX. Any help with this would be greatly appreciated.? Thanks for you patience with a newbie.? Tom, W1TEF |
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Re: Han's fabulous article on the QCX
While I've not used the QCX I know its progenitor the KK7B MiniR2, R2pro, MicroR2
very well and yes?the direct conversion image rejecting RX sounds very very good. I've useed that for SSB TX too. The need for quadrature LO has always been an issue with those and generally a pain of done analog. A decade back I did a design using miniR2/T2 as an upconverting 6M radio. The uR2 works as well at 1mhz as 200 same performance.? So why not use it?? at higher?? ?No reason not to.? While its full analog its not hard to get I/Q? LO right when its fixed.? Sideband selection is at audio.? Narrow filters, do it at audio. In process is a HF upconverting radio using the microR2/MicroT2 ?as the IF (basically half the uBITX) with one mod rather than running them with a VFO at 40M I moved them to?36mhz(fixed) and upconvert to that.? As a wide tuning RX its simpler than uBitx as only two oscillators are needed and one can be a crystal as its a common frequency.? The other is one conversion.? For TX I did not go wide band as I only wanted to TX on the standard bands (80,40,20,15,10) so band pass after conversion and lowpass on TX. How this is relevant.? My experience with 36mhz down converting TX showed the image and spur issue and filters were planned anyway so it was a not a lock out.? However moving the micrR2 and T2 to 64mhz or higher is fairly trivial as its a fixed frequency and 64mhz crystals (for the LO) are common or the Si5351.? ?With that in place and some simplification a wide 1.8-30mhz tuning upconverting TRX is now a known thing.? No crystal filters and a whole lot less RF hardware.? Its superhet but bridges the usual issues of mushy filters and tuning the IQ LO.? The 5351 solves the issue of a lo from 64mhz to 94mhz. While those radios were specifcally for SSB based work CW can be done the same way as the ubitx, inject DC into the TX mod and carrier out. Add sidetone and move the TX frequency (down converting LO) for the correct offset and go. The QCX is an example of how non-superhet radios can make inroads when? the quadrature LO or any LO solution is as simple as a Arduino and 5351. Some would argue code is complex but once done its always reusable. Rick Campbell and Dan Tayloe and others gave us a better set of tools to solve the issue. Allison |
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Re: PTT Question
Lawrence Macionski
Not to start an "oil thread" = motorcycle & aircraft? bloggers go on for months each time someone says "what about oil?" |
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uBITX physical comm port - newbie question
First, thanks for letting me join - appreciate it.? The question I'm asking is pretty simple, but I have no experience with this at all.? I've put my uBITX together and it works - really cool too I might add. I looked around, but I can't find any installation instruction or guides with respect to putting the physical USB Comm port connector into the uBITX. Any help with this would be greatly appreciated.? Thanks for you patience with a newbie.? Tom, W1TEF
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Re: Power supply question
You may use a higher voltage.? A regulator and appropriate capacitors might seem like a wise choice, but a regulator such as an LM340-12 requires a minimum 2.5-volt difference between the input and output voltage, so a regulator won't do the job unless you have a 14.5V DC input.? And that's the minimum. The Texas Instruments datasheet shows an LM340-12 operating with a 19V input and a 12V output.
The TDA2822 amplifier chip has an upper voltage input of +15V.? The bipolar (2N3904 and 2N3906) transistors can handle a voltage as high as 30V.? The FETs (IRF510) can handle up to 30V.? Likewise, the 78L05 voltage regulator that biases the FETs can handle an input voltage as high as 30V.? The relays on my board (HFD27/012S) have a recommended coil voltage of 12V, but the voltage can go as high as 24V without harm.? There are several diodes across relay coils, but without a bill of materials I can't determine a reverse-voltage rating for them but it's likely above 13.8 volts. Have fun. -- Jon Titus, KZ1G Herriman, UT USA |
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Re: RF power chain mods and improvements..
William,
Do run it though a spec ana.? While your at it look for the 11.995mhz IF spur (BFO) as that shows up too despite the 45mhz filter.? ?Fortunately its fairly fixed and? low level. Between the HP8568B and the Rigol I get to see a lot.? That and measure a lot using the 4191A impedance analyzer.? I have a decent RF bench. More eyes on this may see other things I may have missed or haven't thought of. If I were doing the board I would consider splitting the RX path and tx path before the 45mhz mixer. as both have different level and filter needs. Its a real challenge to do this well and at low cost. there are a lot of competing considerations and limitations.? So this base board makes a good study and? working example. The biggest issue is with more filters there is a need for more selectors for? what filter is in place and relays or diodes will do it but IO from the MPU becomes the issue.? One thing I've considered is a another atmega328P (bare with crystal or a pro-mini)? doing all the relay IO and a simple 1wire link from the?Raduino to it to command what relays are set and TX or RX. I happen to like that as it frees up pins at the Radiuno.? Right now that is ahead. Allison |
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Re: RF power chain mods and improvements..
Allison, and others... It seems that a common thread in all this discussion of spurs and their taming is that if you don't over-drive the mixer by turning the modulation too high, the spurs are usually within tolerance.? I wonder if that is the reason that Farhan did not provide a gain control for the transmit audio path?? Arv _._ On Sat, Jun 2, 2018 at 10:25 AM ajparent1/KB1GMX <kb1gmx@...> wrote: Additional note... |
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Re: 630 Meters
The two main problems I see with such a project are:
1. the LO being too close to the 45Mhz IF for good supression of the image with the existing filter arrangement, and 2. the ferites in the PA section will have to be swapped out for a mix good at LF/MF such as #73, #31, Mix-J, or something similar. On the bright side, at that frequency you can get gobs of output power from IRF530/540s [or similar inexpensive FETs] without much difficulty. |
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Re: RF power chain mods and improvements..
Additional note...
The threshold for the DBM is -19db out at the signal frequency puts the spur about -64dbm or 45db down.? This level holds for 18 mhz and up.? drive it? harder and the spur grows faster. at -12dbm the spur is barely 30db down. The is typical of DBMs, If LO is 7dbm the 1db compression point is about? that for a second frequency of -10dbm down and the output is minus insertion loss of about 7db so the signal desired is -17dbm.? That is before the low pass filter which?has some loss. One step I took was to put in a SBL1 commercial level 7 DBM and the? were within 1db of the internal mixer so a faulty mixer is not the case. Port mismatch was tested by inserting 3db attenuators.? If the errant? signal drops more than 3DB then port mismatch is a problem.? It was not. I have other steps to confirm and consider but? filtering for those? bands is a likely solution. Allison |
Joel Fournol
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