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Re: FW: [BITX20] RD16HHF1 power curve flattening...some
I vote for making the PA output transformer primary winding centertapped,
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and feeding Vcc into that center tap instead of using the two chokes from Vcc to the drains. When using LTSpice to simulate it takes a long time for the current through the chokes to ramp up, and thus a lot of lost time to simulate.? The action when feeding from the centertap is instantaneous. Almost equivalent is using a separate centertapped inductor to feed power as done on the wa2eby amp. Has the advantage of spreading the load across the two different toroids. The chokes work.? The centertapped transformer (or separate centertapped inductor) is simpler, easier to simulate, and more commonly encountered elsewhere. Jerry On Sun, May 6, 2018 at 06:44 am, K9HZ wrote:
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Re: ND6T AGC implementation for uBIT-X
Jerry,
What is the goal here? Is a wattmeter function really needed inside the ubitx? Or would it be better as an external attachment that can be used with other equipment? For me, measurement of the reverse power is the primary measurement needed inside the ubitx. It is useful for adjusting an external tuner and for deciding if the ubitx is at risk from a bad load. I am using the simple circuit at the nd6t site to get the reverse power measurement. Right now I am using an external analog meter but I have an adafruit ADS1015 that I am going to use when I get my ubitx working again. I am using a little 4x4 breadboard to make an I2C bus expander and the ADS1015 will feed into this along with the I2C lcd. Coding for this is extremely simple. You don't even have to convert to volts. Just display the reading from the ads1015. As it goes down you know the reverse power is going down. If you want to do it with an analog pin on the nano you can do that too. Just my 2cents. FWIW. On Sat, 05 May 2018 15:52:36 -0700 "Jerry Gaffke via Groups.Io" <jgaffke@...> wrote: Kees, |
Re: ND6T AGC implementation for uBIT-X
Here's my unproven code for displaying forward and reverse power in Watts
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plus SWR on the bottom line of the 16x2 LCD, when using a TandemMatch with diode detectors. It's actually quite simple and not computationally expensive..? Hereby released under GPL v3.0 Could be made more accurate by adding the schottky diode drop to the two voltage readings. Assuming the transformer turns ratios are kept at 10:1, the SWR should be reasonably accurate without calibration.? Especially if a few uA of bias is added to the diodes. Power readings should be reasonably accurate if the SWR is close to 1:1 since they assume a 50 ohm load. Maximum analogRead() return value is 1023, and represents a peak RF voltage of 5 volts. Given the 10:1 turns ratio and assuming there is zero reflected power, that's an RF peak voltage at the antenna jack of 50 volts, and an rms RF voltage of? 50/sqrt(2).? Assuming an antenna load of 50 ohms, that's a power of? ?(50/sqrt(2)) * (50/sqrt(2)) / 50 ohms = 25.0 watts. From this, we determine the value of PSCALE in the code below. Using the linear-in-db ad8307 could be done with the same code, but first using a table lookup to convert to RF volts. I don't really want to be computing anti-logs on a Nano. A table lookup will burn some flash. ################################################################ // Print val as d digits with r digits after the decimal point
// Will print any leading zeros, if r==0 then no decimal point
void pnum(uint32_t val, uint8_t d, uint8_t r) {
? uint32_t? div=1;
? uint8_t? ?n;?
? for (n=1; n<d; n++)? div*=10;
? while (div>0) {
? ? if (d--==r)? ?lcd.print('.');
? ? ? ? lcd.print((val/div) + 0x30);
? ? val = val%div;
? ? div = div/10;
? }
}
?
// Read TandemMatch's 2 detectors, display forward and reverse power, swr
#define PSCALE? (1023L*1023/(25*10)) // ADC max of 1023 is 25 Watts, display Watts*10
void? show_swr() {? // SWR = (1+1.0*vr/vf)/(1-1.0*vr/vf);
? uint32_t vr, vf, swr; // Voltage squared proportional to power
? vf = analogRead(RF_FWD); // Peak RF volts from forward detector
? vr = analogRead(RF_REV); // Peak RF volts from reverse detector
? if (vr>=vf) swr=0; // If vr,vf illegal, force SWR to zero
? else {
? ? swr = (vr*1024)/vf; // Voltage ratio, 10 fractional bits
? ? swr = (1000*(1024+swr))/(1024-swr); // 1000*swr, nearly 10 fractional bits
? ? swr = (swr+50)/100; // 10*swr, rounded to nearest tenth
? ? if (swr>99) swr=99;? // Display a max SWR of 9.9
? }
? lcd.setCursor(0, 1); // Fill bottom LCD line, example:
? lcd.print('f'); pnum(vf*vf/PSCALE,3,1); // "f12.4 r03.1 s1.7"
? lcd.print('r'); pnum(vr*vf/PSCALE,3,1); // with fwd,rev power in watts
? lcd.print('s'); pnum(swr,2,1); // and swr to max of 9.9
}
#################################################################
My primary reason not to mess with ad8307's is that they are harder to dead bug. If the timing skew between forward/reverse readings is an issue, I'd definitely try the cap. Likely still accurate enough.? Bill wrote: >?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,
On Sat, May 5, 2018 at 10:45 pm, K9HZ wrote:
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Re: 45Mhz crystal filter specification
I'm using a direct probe. The 815 has a 50ohm input which should be a
match to most points in the ubitx. At least a close enough match to not directly affect the circuits operation. I suppose I could use a 10x scope probe but I'm not sure that would make much difference. tim ab0wr On Sun, 06 May 2018 01:03:42 -0700 freefuel@... wrote: Hi Tim, |
FW: [BITX20] RD16HHF1 power curve flattening...some
¿ªÔÆÌåÓýAshhar¡ see this result too.? The PA output transformer is sub-optimal so some of us have found.? Needs to be 2T:3T and frequency compensated by a cap across the primary.? My simulations show something in the 330-450pf range as optimal for this configuration, but that is through simulations. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] [mailto:[email protected]] On Behalf Of John ? Hello Nik, |
Re: Need help understanding a line of code in ubitx_si5351.cpp (msxp2 = ...)
#radiuno
It is admittedly obtuse code.??
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Pretty much by nature, as the registers on the si5351 are rather obtuse. But I convinced myself it was correct (with no overflows) before releasing it. I doubt most users of other si5351 libraries ever manage to figure them out either. I invented the scheme for downshifting b and c of (a+b/c) till c fits in its 20 bit register as a way of doing these computations in 32 bit integer math.? But later found a similar trick in apnotes for sister part si5338, so the technique has been blessed by SiLabs. The si5338 notes were created before my re-invention. A new set of eyes may find bugs I didn't see. Let me know if you find anything. Or have any further questions. Everyone incorporating my code feels obliged to make minor changes to style. The original code is in? ??/g/BITX20/files/KE7ER/si5351bx_0_0.ino There are errors and inconsistencies and omissions in that AN619 doc. In particular, the Fvco/Fout ratio of (a+b/c) is restricted to values of 8.0 through 1800.0 inclusive, it's also possible to special case integer values of 4 and 6 but we do not use that. The PLL msynth ratio is of course restricted to those values of Fvco/Fxtal that give a Fvco of 600-900 mhz, so for an Fxtal of 25mhz that's values between 24.0 and 36.0 inclusive.?? Register 36 is shown incorrectly in the summary on page 36. And the document does not give enough information about which registers need to be initialized. The ClockBuilderPro software from SiLabs can help resolve some of that, but does some stuff not documented at all in AN619, initializes registers that don't need it, and hunts for elusive msynth register values using small integers in b and c but avoids the msynth's integer mode.?? Jerry, KE7ER On Sun, May 6, 2018 at 05:30 am, David Feldman wrote: 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.) |
Re: boosting the power on 28 MHz
#ubitx
¿ªÔÆÌåÓý¡°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 ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] [mailto:[email protected]] 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=[email protected]> wrote:
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Re: ND6T AGC implementation for uBIT-X
¿ªÔÆÌåÓýYes, 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 ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] [mailto:[email protected]] 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. 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 |
Re: Need help understanding a line of code in ubitx_si5351.cpp (msxp2 = ...)
#radiuno
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 |
Re: boosting the power on 28 MHz
#ubitx
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=[email protected]> wrote: Ashar, |
Re: boosting the power on 28 MHz
#ubitx
Ashar,
Is this mod going to be implemented on new production? Thanks! 73 Steve G1KQH |
Re: No PTT
Geoff Theasby
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
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
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?? |
ubitx_20.ino does not compile, anybody else encounter this?
#ubitx-help
#ubitx
#arduino
#firmware
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? |