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Re: uBitx Unfiltered
Kee's
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Are you talking filters at the output of the rig, for use with current v3 and v4 boards? That's likely the best bet for getting current rigs compliant. Me, I'm ok with dropping the high bands, maybe stick with just 80,40,20m. Killing spurs at 15m and 12m is difficult, and perhaps not worth the trouble at our latitudes given where we're at in the sunspot cycle. The current four transmit LPF's are sufficient for harmonic suppression if the board routing and relay scheme is clean. Not sure what a "basic dual relay" scheme is. I think the relay scheme of post 58293 is sufficient. Regarding where this rig should go on v5: Allison has said repeatedly that we need band specific band-pass filters where we currently have one 30mhz LPF at L1,2,3,4. She's built lots of this stuff and I respect her opinion. That's how pretty much all reg-compliant radios are built. But I am still very curious if we can tame the objectionable spurs with these changes: 1)? ?Use a PX1002 86.85mhz SAW filter instead of the 45mhz crystal filter (and appropriate transistors and transformers) 2)? ?Bring the local oscillators up to the required 7dBm.going into the mixers, keep mixer input signal levels 10dB below that 3)? ?Avoid having stuff from the power amp get into the IF amps. If that is sufficient to bring the spurs into compliance, we keep the radio almost as simple as it is now. The primary added complexity is additional gain required in the power amp to deal with the reduced signal from the mixers.? Somewhat related:? Clean up layout so the BFO does not jump across the 12mhz filter. Jerry,? KE7ER On Sat, Sep 1, 2018 at 09:20 AM, Kees T wrote:
Since most keep talking about the need for BPFs for certain bands, I "guess" the 80m-10m uBITX direction should be a board with 6 filter capability. How about a?basic?dual relay?switched filter board (3-1/4" x 3-7/8") with?up to?6 pluggable filters, all?manually?selected with a 6 position rotary switch --AND-- you can add a small mux board with 2N3904 relay drivers for the filters and a CD4028B mux to go from the 3 Raduino pins to the filters. Start with the existing 111,110,100,000 and add two others when you have the code modified. |
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Re: CW PTT attack time to slow
#ubitx
Joop Stakenborg
¿ªÔÆÌåÓý
Okay! Sounds good, will have a look. I¡¯m afraid the stock firmware is unusable for serious CW transmissions. Thanks, Joop PG4I
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Re: CW PTT attack time to slow
#ubitx
Joop Stakenborg
Op 1 sep. 2018, om 03:41 heeft ajparent1/KB1GMX <kb1gmx@...> het volgende geschreven:Thanks Allison, I have now tried both the recent V4.3 from GitHub and KD8CEC¡¯s version. Ian¡¯s version works a bit better, attack time is improved but I am still missing part of the first dit to dah. The biggest issue is the software is a big loop and CW ke is checkedThanks for responding Regards Joop |
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Re: uBitx Unfiltered
Makes more sense in this thread.............
Since most keep talking about the need for BPFs for certain bands, I "guess" the 80m-10m uBITX direction should be a board with 6 filter capability. How about a?basic?dual relay?switched filter board (3-1/4" x 3-7/8") with?up to?6 pluggable filters, all?manually?selected with a 6 position rotary switch --AND-- you can add a small mux board with 2N3904 relay drivers for the filters and a CD4028B mux to go from the 3 Raduino pins to the filters. Start with the existing 111,110,100,000 and add two others when you have the code modified. 73 Kees K5BCQ? |
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Re: KARMA and BITX
Lawrence Macionski
Answer. The comment means- apparently someone is successful in the realm of electronics and ham radio. Another coincidental BITX success? It is simply newsworthy and I wish him well. Just like when Ashhar Farhan was inducted into CQ Amateur Radio Hall of Fame and noted here as well. Both men deserving.
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Re: Which xmit transistor is blown?
Sean,
Its been several days since you posted likely its eben seens and everyone is going "I dunno". ? ?Not enough description of whats going on or not going on. ? ?Not sure of the mods done. ? ?Are you sure the power supply is working ok. Everyone running FT8? without big fans seems to fry the amp and yet people run FT8 and likely at max power possible.? ?While technically it ignoring spurs and harmonics can there is insufficient cooling for sustained long transmit sessions.? HINT: cooling required. FYI hot is how hot?? You get a blister?? You don't what to hold your finger there long?? You feel warmth but its not painful? Many of the devices will heat to the very warm (about 140-150F).? That is not deadly to the devices.? It will make things like bad soldering stand out and maybe other marginal components fail.? Some have noted board level issues like open vias. Allison ? |
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Re: UBITX V3 TX GAIN VARIATIONS
Jerry KE7ER,
>>I'll be buying that amp, once Hans starts selling it..?Then cut off the back half of my uBitx with a hacksaw. And you have half a radio....? That amp expect about 12-14dbm drive from the radio its attached to. That means for ubitx you still need about 32-34 db of gain hopefully not 3904s from the mixer output to the amp...? and still need a band pass filters for the bands above 17M and low pass filters, and there are issues with ground loops in the modulator and IF area. Its total gain is about 26-28DB.? To get from the mixer output though filters and result in 10W you need about 60DB of gain.? ? If you want even performance 3-30mhz you need to design that predriver section to be flat.? ? Which by the way is half the reason why the current amp has low power at 10M. As to the comment > Bag, cat, QSX amp.? The cats out of the bag, and its a QSX amp. Allison |
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Re: VK4PP uBitx LPF BANK add-on Board
Timothy,
Have you ever looked at the board??? Fixing the driver moved the problem sage back to the predriver and first amp. Pulling bands at the time of its design was not considered as it was desired to have a 3-30mhz radio unbounded by "bands".? ?I agree a bounded transmitter is a must? but at that time it wasn't heard. Allison |
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Re: VK4PP uBitx LPF BANK add-on Board
Timothy Fidler
If it is done cleanly it could look quite nice. Specifically small copper lugs can be soldered on the bottoms of the existing control relay pins to attach to braided core Cu wires which are then hot melt glued to the underside of the PCB for strength and brought out to a? green plastic header male plug?
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that is why I suggested the click in header carrying all voltage GND and the three signals to the PCB designer. If there is a known good solution to the existing issues that does not require a masters in EE to source and solder up then A Farhan has a prayer at moving? the remaining uBitx boards in Inventory.? Some people will chose to operate the thing unmodded and some with legal sensitivities will want a fix. After that inventory is moved, I suspect a full rework of the PCB will be out of the Eastern Horizon. My guess. Hopefully with AGC? and so on. Maybe with BS170 x 2? in the driver stage .? But what is set up as a standard as to what the relay control signals mean now will have to be carried through,? or all hope of? forward software compatibility will fly out the window. That is why a one of ten decoder to use those three lines makes a whole lot of sense even if it adds dollars to the price of the finished board. If you start pulling 15 and 17 metres off the table,? (combined filter) the multiband nature of the beast is compromised.? ? Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2?
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Re: VK4PP uBitx LPF BANK add-on Board
Yes, it would be a lot easier to simply disable the LPF's and use external filters.
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As per the final sentence here from long ago, keeps things very simple:?? ? ? /g/BITX20/message/30530 Given the uBitx board layout, trying to get more power on the upper bands will likely add to the spurs due to coupling from power amp to the IF stages. Board layout around the IRF510's is not that good for 30mhz, and the upper bands have more trouble with spurs.? I'd be happy with 80m,40m,20m, which the current uBitx can do a reasonable job of using external filters. But replacing the power amp would solve most of those issues.? No need for the hacksaw, just disable the uBitx power amp. Use coax for signals, I doubt the cabling will be much of an issue. Can experiment with band specific filters in that coax from exciter to power amp if necessary. Still need to address mixer levels, IF gain distribution, and a layout issue that allows the carrier to sneak around the 12mhz crystal filter. But the uBitx does give us a very simple analog SSB exciter/receiver to work with. Hacking up a uBitx to perform well with minimal cost and complexity might help give direction to future versions from hfsignals. Note that the G0UPL power amp will require nearly 20 dBm of power from the exciter.? Final mixer of the uBitx exciter should have about -3dBm max going in (10 dB below the 7dBm local oscillator), and loses 6dB.? So will want up to 30dB of gain between the uBitx exciter?and the G0UPL power amp, perhaps two MMIC's built ugly style on the back of the uBitx.? Not exactly trivial. Jerry On Sat, Sep 1, 2018 at 06:29 AM, MadRadioModder wrote:
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Re: VK4PP uBitx LPF BANK add-on Board
¿ªÔÆÌåÓýMy thinking is that this whole discussion of? butchering the uBITx board and cobbling in another board that, in itself, will have some sensitivities to things like cable runs and connections etc. will scare the unseasoned builder away from the uBITx completely.? ? I used what I thought was a better solution for some of the hams near me¡ by simply jumpering/cutting out the whole LPF network¡ so there is raw straight from the PA RF at the output.? I then used one of Hans¡¯ BPF modules outside the box with a minimal BNC to pins ¨C BPF ¨C pins to BNC that is about $5 worth of parts including the filter.? Now granted you must buy all of the filters for bands you want to operate¡ but it¡¯s the same with any LPF replacement.? A complete board in an outboard box is even less scary to most.? Yes the rest of us will be at the uBITx endlessly with our hack saws, hot glue, and soldering irons¡ but that will only work for us hackish engineering students. -- ¡_. _._ |
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Re: VK4PP uBitx LPF BANK add-on Board
Timothy Fidler
The flaming obvious and yet trivial? has? just occurred. How are people going to mount the PCB as shown ?? Three hole posns at a minimum will be required for say 3.4mm holes.? Edge distances have to be allowed.? As long as it can be mounted on a bit of AL with a return on one side it can be bolted anywhere. As it stands it will have to be (hot melt glued ??) to something ..a bit like skyhooks required on some engineering projects in a way.? ?Even if people have to drill out prescribed rondels for the screw down on Rx of the board to keep the price down,? they still need to be nominated.?
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Re: 4.2¡± Nextion Bezel?
He is getting a laser cut acrylic version. I offered to print a few if he provided the material to produce the object . Instead they went with laser cut acrylic.?
Ill get s copy of that object in case it comes up again and some one is ok with white or whatever color I happen to have.? |
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KD8CEC v.1.095 CW Issue
#ubitx
#ubitxcw
#ubitx-help
I am sure I missed this topic, but my keyer worked fine until I upgraded the firmware to KD8CEC's V. 1.095 for use with my 4.3-inch Nextion?display. Since the upgrade, I can only use a straight?key. What did I miss??
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Re: CW PTT attack time to slow
#ubitx
On w0eb.com webpage is NANO software that implements interrupt driven CW generation.? Also eliminates the voltage divider scheme.? Also eliminates the need to switch between straight key and paddle as both are always active. rOn On August 31, 2018 at 9:41 PM ajparent1/KB1GMX <kb1gmx@...> wrote: |
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Re: UBITX V3 TX GAIN VARIATIONS
I'm convinced Hans did a good job.
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Especially after seeing this in his post: ? "I am very grateful to Allison KB1GMX for her advice, encouragement, support and testing during the development of this Linear PA." I'll be buying that amp, once Hans starts selling it.. Then cut off the back half of my uBitx with a hacksaw. I had thought of the BS170 in regard to the uBitx in months past, but figured it might be too lightweight when used as a linear. And didn't fancy dealing with two more bias pots. Will be interesting to see how Hans went about it > Bag, cat, QSX amp. I've heard of bag phones, though not bag HF linear amps. And radio has been explained through the metaphor of a very long cat (or lack thereof) But still seems a bit cryptic. Jerry, KE7ER On Fri, Aug 31, 2018 at 06:20 PM, ajparent1/KB1GMX wrote:
Jerry, |
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Re: UBITX V3 TX GAIN VARIATIONS
Jerry KE7ER,
The key to make it fly is layout to avoid ground loops and parasitics and attention to cooling and that includes the BS170s. There are pictures of his board. and for that fact the Softrock.? Many devices will tolerate high peak power if a little attention is given to cooling. The reason the amp works well is the BS170s aren't being flogged to drive the IRF510s. and both with care have enough gain for the task.? There is ample headroom as 10W needs about .5W from them and they can do 1W. It did run at 10W swept frequency for over an hour.? I was interrupted and forgot it, while I was doing something else.? At the 10W power level I've not yet found anything that kills it.? Even when running into reactive loads. Allison |
MadRadioModder
David Posthuma
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