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¿ªÔÆÌåÓýactually, $0.02 buys
a quite a bit of a blue pill ......? On 6/03/2018 12:19 PM, Fred Buecker
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Re: Ubitx audio debug question
Thank you, Raj!
I'm wondering if U1 TDA2822 might be bad.? Visually it looks OK and it doesn't smell burnt, but I have no static or hiss in the speaker by touching potentiometer leads, etc.? I ohm'd out connections from the TDA2822 pin 1 to the pot and the speaker via C77 and they look good.? I confirmed that pin 7 goes to VOL-M via the orange wire.? On item that confuses me a little is the wiring instructions show a 100K pot with no on-off switch connections, while my pot is 10k with on-off.? Also the instructions say to attach the green wire to the pot ground lug but my 10k pot does not connect any of the 3 lugs to ground (instead, the green wire gets ground via the ubitx board connector).? Unfortunately, I no longer have an oscope, so I'm limited to how much I can check on U1.? It does show good 12v to pin 2.? I'm thinking I may need to order another TDA2822 and replace it (if I don't get a scope soon enough to do more checking).? If I do replace it, I wonder if it would cause any issues if I put in an IC socket for mounting? I'm open to anything obvious anyone might see that I'm missing.? Enclosed are pictures of my pot wiring and U1. Thanks! Tom AB7WT |
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The days are quite a bit longer down there this time of year.
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Apparently. On Mon, Mar 5, 2018 at 09:09 pm, Nik VK4PLN wrote: We will end up converting this uBITX in to an SDR by the end of the day... |
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Re: #uBiTx CW RF power out
#ubitx
Set bias for 100ma of drain current on each IRF510 using RV2 and RV3 and then leave it be.
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That 100ma shouldn't change much even if you were to go from a 12v PA-PWR to 24v.? Adjust power level using RV1 on the uBitx.??(RV1 sets IRF510 drain current on the Bitx40) For SSB, could also vary power level by adjusting the mike gain at Q6 somehow. I assume the smoked U1 was marked "WX".? Can you verify? The WX clones blow for no particular reason. The WX probably works reliably if the supply voltage is reduced to 5v or so, down from 12v. Search for "TDA2822" in this forum to see some nice long discussions The NTE7155 will probably work fine, perhaps you could report back on that too. > The first signal reports were the audio was poor with too much high frequencies and no mid to low. Sounds like the 12mhz bfo is positioned incorrectly relative to the passband of the crystal filter. Should be able adjust your audio (both transmit and receive, affects both equally) by using the calibration routine in the Raduino for the bfo frequency adjust. Jerry, KE7ER On Mon, Mar 5, 2018 at 07:23 pm, Bob wrote:
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A 15kHz DSP IF will be fantastic .... no need for a separate CW crystal filter, get a notch filter, noise reduction, variable brick wall bandpass, etc. M On Tue, 6 Mar 2018 at 2:19 PM, Fred Buecker <tfbiii2002@...> wrote:
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Re: #uBiTx CW RF power out
#ubitx
Bob:
Search this list for your answers. See especially the thread "rv2_messed_up_setting_and_txing_like_mad!!!" This goes into some detail about adjusting the RV pots. john AD5YE |
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#uBiTx CW RF power out
#ubitx
¿ªÔÆÌåÓýI received my uBiTx about two weeks ago.? I experienced some of the same issues that others have reported: 1.????? I did find that the wiring diagram for the three 3.5mm jacks to be confusing and the pin numbers/locations on the supplied jacks did not match the drawing. 2.????? I smoked U1. Probably because I plug a speaker with a tip/sleeve into the Speaker jack.? I found that the NTE7155 is suppose to be a replacement and I could find one locally.? I did use an IC socket so I can easily replace it with a TDA2822 if necessary.? I also disconnected the audio out from the ring of the Speaker jack as a precaution. 3.????? I also did not have any current variation after the PA bias was set.? This was because I miss wired the electrets mic. 4.????? The first signal reports were the audio was poor with too much high frequencies and no mid to low. ?Before I tackle the audio issue I want to get a handle on the RF power out. 5.????? The CW RF power out is more than I expected.? The below table shows some of the measurements that I see on my setup. ( Yes I know that some of the results are counter intuitive.? Unless someone knows otherwise will write it off to change in biasing in one or more circuits):
? I also set the PA bias in using an oscilloscope at the antenna connector connected to a dummy load and adjusting Rv2 and Rv3 alternately in 5 Volt increments until the Wattmeter showed 10 Watts. My question is how to set the maximum power? Use Rv2 and Rv3 to set the bias or use Rv1 to back off the drive after the bias has been set using Rv2 and Rv3. ? Bob ¨C KE7JL ? ? |
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Re: Fldigi with UBITX
On Mon, Mar 5, 2018 at 03:04 pm, Tim Gorman wrote:
Walter, You might be able to get them cheeper elswhere.? I have had these on some various ham equipment for a number of years.? these work great and have yet to fail. These come with a rubber cover on them.? Don't take them off they will conduct. I just put then on the heat sink in different ways and they turn my fan on and off.? simple. I know some are thinking, Build it out of electronics, but some things are just fine kept simple. ? -- 73, W9KJO Walter |
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Re: CAT Support uBITX Firmware CEC Version 1.04 Release
#ubitx
Bob Tanks for feed back. I often test with nano only.? I sometimes did not make A6 High, so I did not know if CW-Key was being pressed and I had a hard time trying to catch a bug. so?I have now soldered the test Nano. Ian KD8CEC 2018-03-06 7:21 GMT+09:00 Robert McClements <gm4cid@...>: No uBitx yet but CECBT 1.04 working well with Nano and I2C 20x4 lcd display and HRD control cat is fine. |
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Postage from the US to down here in Oz is now unbelievably expensive compared with what the rates were a few years ago. And we also face the current exchange rate plus the money changers margin. By contrast, the Chinese suppliers often work in Australian currency and free postage. I am sorry guys, but that makes it hard for US suppliers to compete. An item on eBay costing USD10.00 may cost an extra USD50.00 to get it here.
-- Kevin B. G. Luxford kbgluxford@... |
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Fred Buecker
I look at it that the Arduino is an "easy" way to get the job done. It doesn't mean it's the best, but things like a Teensy and a Blue Pill can take a bit more time to get working the right way. Although, they might open the door to new features or solve old problems. That's my $.02 -Fred KC3HMS On Mar 5, 2018 6:20 PM, "Michael Monteith via Groups.Io" <michael_r_monteith=[email protected]> wrote: ? Honestly, it's great to see people thinking outside the box.? Coming up with all sorts of options for people to use their favorite microcontroller.?? That's what is great about the Bitx and uBitx.?? It sure has got a lot of people active in all areas.? It's interesting to me as I've been into electronics, programming, and microcontrollers.? I'm just very new to RF.?? Getting to have it all together is really cool.? |
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Re: ubitx order
Fred Buecker
I'm going to order mine next month, has it shipped yet? On Mar 5, 2018 7:07 PM, "James Tate" <kw4sz@...> wrote:
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Re: Modifying Bitx40 BPF band pass filter
PH0KKO You can change the BPF filter center frequency by just changing the capacitors, but there is a potential problem.? As the capacitance gets higher the filter bandwidth gets narrower.? You can see this action by emulating the filter in LTSpice circuit simulator.? It may be that you only need to add a small amount of capacitance and the filter bandwidth will remain within usable range.? It may be possible to still add turns to the existing toroids.? If you can poke a small hole through the glue you might be able to add a turn or so in series with existing windings.? This might not look pretty but it should be functional.? It is possible to manually measure filter bandwidth if you have a stable oscillator that will tune over the frequency range.? Add a 6db pad on input and output to maintain proper terminating impedance and use a detector and DC meter to monitor output versus input over the filter bandwidth.? You may want to convert resulting measurements into db instead of volts. Hope some of this helps. Arv? K7HKL _._ On Mon, Mar 5, 2018 at 5:36 PM, <kaapstad1@...> wrote:
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Modifying Bitx40 BPF band pass filter
Hi all, I am building the Bitx40 dead bug style. Basically changing the Bitx20 and using a different BPF, VFO frequency and low pass filter. For the BPF I used the design shown on the hfsigs website. Instead of T30-6 I used three T37-6 I had lying around, added 5 extra turns (45 in total) on each toroid which came to 6 uH as well. It turns out the signal peaks at around 7.550 MHz which is too high in frequency.? What would be the best way to lower the center frequency of this filter? I have the toroids covered in glue so if it is possible by addjusting the capacitor values only. If the filter becomes wider that would not be a problem at all. I use an IF of 10 MHz and a VFO of 17 so there will not be many harmonics in the 40 meter band. I would appreciate it if someone can point me in the right direction. Thanks, PH0KKO |
Nick VK4PP
N1AFF - formerly KB1JPW