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Re: DISASTER !!
LKNDAVE
the diode on the bottom of the nano. near the usb conn. i put in a 1n400xs, fixes most of them. stinky
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Re: boosting the power on 28 MHz
#ubitx
K9HZ <bill@...>
“However, the new PCB has pads for the RD16HHF1”
Thank you !!!!!!
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois
Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook!
Moderator – North American QRO Group at Groups.IO.
email: bill@...
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Ashhar Farhan
Yes, the plan was to use an RD device for the new version. We ran into availability issues. The lead time from Mitsuibishi was 10 weeks. So, I took a call to continue with the IRF510s. However, the new PCB has pads for the RD16HHF1 as well as the IRF510s. - f
On Sun, 6 May 2018, 16:05 G1KQH via Groups.Io, <g1kqh=yahoo.co.uk@groups.io> wrote:
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Re: ND6T AGC implementation for uBIT-X
K9HZ <bill@...>
Yes, you’ve got it. The Nyquist sampling theory sets the limit of resolving the Power (and hence SWR), and the A/D rate needs to be faster than that or it won’t work properly. For a 3 KHz signal that’s about 10 KHz…and as you point out that’s above the default sampling rate. 58.6 KHz would be ok, but to get that rate probably assumes that the processor is dedicated to the task, not off doing other uBITx work, although there is probably some clever way to get the measurement pairs close to each other by ignoring some other operations momentarily. Averaging is the only way to overcome this and, statistically, the quality of the answer depends on the symmetry of the wave form (e.g. will probably work perfectly for CW and be mixed for SSB).
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois
Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook!
Moderator – North American QRO Group at Groups.IO.
email: bill@...
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jerry Gaffke via Groups.Io
That's a good point, skew between ADC reads could trash the SWR readings.
Jerry, KE7ER
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Also have some MPSA13 coming in, those are the darlington, not the MPSA18, sorry about the confusion. Part number is pretty well the same except one number.
The 13 is what I meant to ask about using in the drive circuit and realized that after checking the data sheets again this morning. https://www.jameco.com/Jameco/Products/ProdDS/26489.pdf That part has a really high hfe, which is what made me curious. On the range of 5000. -- ---------- N5WLF, Greggory (or my nickname, Ghericoan) General Class, Digital Radio Hobbyist
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The hfe on these is typically 1150. Max is 1500, min is 500. I was curious as to if the higher gain might help with the drive on 30 meters and up.
https://www.jameco.com/Jameco/Products/ProdDS/210681.pdf -- ---------- N5WLF, Greggory (or my nickname, Ghericoan) General Class, Digital Radio Hobbyist
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LKNDAVE
my favorite to92 npn gain guy. bes
ide the xx390x twins the best transistor you can buy. tayda sells .12 each hfe ~400-500
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Re: Need help understanding a line of code in ubitx_si5351.cpp (msxp2 = ...)
#radiuno
David Feldman
Thank you, Jerry - that helps guide me through the code and chip documentation (I was getting puzzled at doing all of these computations in unsigned 32-bit integer space with overflows and stuff to worry about.)
Dave
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Re: boosting the power on 28 MHz
#ubitx
Ashhar Farhan
Yes, the plan was to use an RD device for the new version. We ran into availability issues. The lead time from Mitsuibishi was 10 weeks. So, I took a call to continue with the IRF510s. However, the new PCB has pads for the RD16HHF1 as well as the IRF510s. - f
On Sun, 6 May 2018, 16:05 G1KQH via Groups.Io, <g1kqh=yahoo.co.uk@groups.io> wrote: Ashar,
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Re: boosting the power on 28 MHz
#ubitx
G1KQH
Ashar,
Is this mod going to be implemented on new production? Thanks! 73 Steve G1KQH
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Re: No PTT
Geoff Theasby <geofftheasby@...>
HI John & Jerry, Now see other thread... Geoff
On 2 May 2018 at 15:55, Geoff Theasby <geofftheasby@...> wrote:
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Geoff Theasby <geofftheasby@...>
After stumbling about in the dark, I realised I had not entered Newline or 57600 baud as required. I ran it again and Lo! 1 gives "Equal inputs read by Arduino" 2 gives nothing 3 gives same as 1 4 gives scrolling display, saying "I see a dot, 1-2-3-4-5-" 5 gives scrolling display saying " 1-2-3-4-5-" This is with the Raduino/display only, connected to USB on a Windows 7 laptop. Is this of any help? Regards Geoff G8BM
On 4 May 2018 at 12:01, Geoff Theasby <geofftheasby@...> wrote:
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Re: 45Mhz crystal filter specification
freefuel@...
Hi Tim,
I'm interested to know how your connecting your SA to the circuit, from my recollection the majority of SA equipment has a 50 ohm input impedance, an input impedance that low is not conducive to hanging a probe off the circuit at any convient location. -Justin N2TOH
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ubitx_20.ino does not compile, anybody else encounter this?
#ubitx-help
#ubitx
#arduino
#firmware
freefuel@...
Has anyone else encountered a failure to compile the Arduino Sketch for the ubitx? I am getting an error code for some type of return in the menu portion of the code.
-Justin N2TOH
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Re: ND6T AGC implementation for uBIT-X
K9HZ <bill@...>
Arv…
Hmmm… we should probably take this off-line at this point. This has to do with A/D resolution time vs. filter time.
I’m rethinking…that diodes would be a better choice just because they are less complicated. The transform to watts and SWR is still complex though and will eat some processing power in a Nano.
My tuner is prototyped and the hardware is done. The firmware is in the writing stage… I’m waiting for Jack to finish his Jackal project and a another second follow-up project before I officially ask for his help in coding. It can tune 100 watts from any source (meaning it can be stand-alone… or I2C linked to the uBITx), uses latching relays to conserve power for QRP, has a 1:4 transformer for very low loads like the illusive short length impedances at very low frequency (12 ohms), CL-LC swap for high-low impedance matches of us to almost 12,000 ohms, an AD8302 to generate phase and magnitude information of the load impedance like a point on a smith chart and then calculates the LC transform directly and instantly… no clicking-clacking relays searching for lowest SWR. SWR and power is calculated and can be retrieved over the I2C or analog via the onboard dedicated Arduino (for those interested, the LP-100A watt meter generates power and SWR readings this way). There is also a low power tune mode Dig Out to save the relays and protect the transmitter by commanding lower power (works down to about 250 mW). So far it fits on a 5”x3” board but I may be able to shrink it. Stay tuned.
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois
Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook!
Moderator – North American QRO Group at Groups.IO.
email: bill@...
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Arv Evans
Bill K9HZ Not sure I follow your analysis. The added capacitance lowers upper frequency limit by a significant amount. You can even go as high as 0.1 MFD so that the detector output is filtered to virtually DC, leaving no HF knee in the passband. This does cause a charge period error unless there are multiple samples to charge The Arduino ADC provides 1023 distinct voltage steps. It's internal voltage reference is used for calibration. With a maximum of 5V and 1023 steps this gives a minimum sensitivity of around 0.005V and 5V full scale. That range and resolution seems adequate for most transmitter RF measurements.
It may be interesting to try using conventional diode detection with a small forward bias to overcome the diode offset. This is not usually done in conventional SWR bridges because they are mostly non-powered units. But if the SWR bridge is to be inside a powered transceiver then the bias is readily available. Now that AD8307 prices are more reasonable this device may be a viable alternative detector but it's log slope ADC requires a bit more complex software if you want to derive the full compliment of FWD and REV power, FWD and REV SWR, RF Voltage, RF Current, and possibly RF Impedance. With either diode or AD8307 detectors it should be relatively easy to make the software support automatic calibration. Possibly this could be based on measurement of the known output of one of the Si5351a ports. Using and displaying this output could also be a test point to verify that the synthesizer chip is actually operating at normal levels.
Some time ago you mentioned work on a QRP ATU of your own design for use with BITX transceivers. How and antenna ends of this unit? Might be interesting to include calculation and display of impedance, particularly at the transmitter end of the ATU to help get a good 50 ohm match to the IRF510 finals and associated LPF. As you know, impedance is important when using an LPF designed for a specific cut-off frequency in order to
Arv K7HKL
On Sat, May 5, 2018 at 7:26 PM, K9HZ <bill@...> wrote:
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Re: boosting the power on 28 MHz
#ubitx
K9HZ <bill@...>
Thanks. This confirms what we tried two months ago.
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois
Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook!
Moderator – North American QRO Group at Groups.IO.
email: bill@...
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Ashhar Farhan
So, here are the final mods, Replace C81 from 0.1uf to 470pf Replace R83 from 10 ohms to 2.2 ohm (you can short R83 as well) Replace 97, R98 from 47 ohms to 220 ohms Remove C261, C262.
So, what happens is that removing the C261 and C262 increases the gain of the finals. They are run open. Hence greater gain at 28 mhz. However, the gain is very high at lower frequencies. So, in order to reduce the gain at the lower frequencies, the 0.1 uf cap is replaced by the 470 pf. As the frequency of the signal drops, less and less RF flows through the 470 pf, decreasing the gain of the predriver. 470 pf is not a magical value, 220 pf works almost as well. Here are the pictures at 14 mhz. The two tone test reveals 20 db IMDR, which is alright. If you want to see better, buy yourself two RD16HHF1s.
- f
On Sat, 5 May 2018, 22:02 Kees T, <windy10605@...> wrote:
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Re: boosting the power on 28 MHz
#ubitx
Ashhar Farhan
Jerry, The outputs are as follows (from the log book): 3.5 MHz - 12W 7 MHz - 14W 10 MHz - 11W 14 MHz - 10W 21 MHz - 7.8W 28 MHz - 4.4W (The preset was kept at maximum) - f
On Sun, May 6, 2018 at 10:14 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: Very cool, thanks for digging into this.
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Re: ND6T AGC implementation for uBIT-X
Arv Evans
Bill K9HZ Not sure I follow your analysis. The added capacitance lowers upper frequency limit by a significant amount. You can even go as high as 0.1 MFD so that the detector output is filtered to virtually DC, leaving no HF knee in the passband. This does cause a charge period error unless there are multiple samples to charge this capacitor. Same thing applies to simple diode detection with it's post-detection filter capacitor. The Arduino ADC provides 1023 distinct voltage steps. It's internal voltage reference is used for calibration. With a maximum of 5V and 1023 steps this gives a minimum sensitivity of around 0.005V and 5V full scale. That range and resolution seems adequate for most transmitter RF measurements. It may be interesting to try using conventional diode detection with a small forward bias to overcome the diode offset. This is not usually done in conventional SWR bridges because they are mostly non-powered units. But if the SWR bridge is to be inside a powered transceiver then the bias is readily available. Now that AD8307 prices are more reasonable this device may be a viable alternative detector but it's log slope ADC requires a bit more complex software if you want to derive the full compliment of FWD and REV power, FWD and REV SWR, RF Voltage, RF Current, and possibly RF Impedance. With either diode or AD8307 detectors it should be relatively easy to make the software support automatic calibration. Possibly this could be based on measurement of the known output of one of the Si5351a ports. Using and displaying this output could also be a test point to verify that the synthesizer chip is actually operating at normal levels. Some time ago you mentioned work on a QRP ATU of your own design for use with BITX transceivers. How is that coming along? Are you planning on including SWR and power measurement capability at both input and antenna ends of this unit? Might be interesting to include calculation and display of impedance, particularly at the transmitter end of the ATU to help get a good 50 ohm match to the IRF510 finals and associated LPF. As you know, impedance is important when using an LPF designed for a specific cut-off frequency in order to make the LPF operate within its design parameters. Arv K7HKL _._
On Sat, May 5, 2018 at 7:26 PM, K9HZ <bill@...> wrote:
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Re: boosting the power on 28 MHz
#ubitx
Jerry Gaffke
Very cool, thanks for digging into this.
toggle quoted messageShow quoted text
I tried various schemes in LT-Spice, but improving the final is more difficult than it seems going in. I could seldom correctly predict the results I got. Need to re-read a few chapters of EMRFD. And of course, real hardware is likely quite different than the simulation. So is this still the previously reported 4W at 30m, 13W on 80m? Would raising the PA-PWR voltage to 24v improve that IMDR? Perhaps if keeping power down to something reasonable with RV1, we could get by without up-sizing the heatsinks. Jerry
On Sat, May 5, 2018 at 09:28 pm, Ashhar Farhan wrote:
So, here are the final mods,
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Re: boosting the power on 28 MHz
#ubitx
Ashhar Farhan
I forgot the picture of the experiment. - f
On Sun, 6 May 2018, 09:58 Ashhar Farhan, <farhanbox@...> wrote:
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Re: boosting the power on 28 MHz
#ubitx
Ashhar Farhan
So, here are the final mods, Replace C81 from 0.1uf to 470pf Replace R83 from 10 ohms to 2.2 ohm (you can short R83 as well) Replace 97, R98 from 47 ohms to 220 ohms Remove C261, C262. So, what happens is that removing the C261 and C262 increases the gain of the finals. They are run open. Hence greater gain at 28 mhz. However, the gain is very high at lower frequencies. So, in order to reduce the gain at the lower frequencies, the 0.1 uf cap is replaced by the 470 pf. As the frequency of the signal drops, less and less RF flows through the 470 pf, decreasing the gain of the predriver. 470 pf is not a magical value, 220 pf works almost as well. Here are the pictures at 14 mhz. The two tone test reveals 20 db IMDR, which is alright. If you want to see better, buy yourself two RD16HHF1s. - f
On Sat, 5 May 2018, 22:02 Kees T, <windy10605@...> wrote: Are you able to measure compression for linear operation (SSB) ? Harmonic content and levels ?
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