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Re: Testing QRP Labs Si5351A Synthesiser Module, PCB Rev 4
Hello Joe The Si5351A chip has three stages conceptually: 1) Multiply the 27MHz reference crystal up to an internal VCO frequency, that theoretically must be in the range 600-900MHz 2) Divide down in the "MultiSynth" divider 3) Divide by a further power of 2, division ratios available are powers of 2, from 1 to 128 All of these multipliers and dividers have limitations on how big their ratio is. To reach down to LF you need to use the division stage.? If you the example 3 .ino you will see this line of code: setupMultisynth(SI_SYNTH_MS_0, divider, SI_R_DIV_1); That SI_R_DIV_1 is the thing you need to change. You can use SI_R_DIV_1, SI_R_DIV_2, SI_R_DIV_4 etc all the way (in powers of two) up to SI_R_DIV_128.? So for your target output frequency, 136kHz say, you might choose SI_R_DIV_8. Then set the frequency up at 136kHz x 8 = 1.088MHz.? Using SI_R_DIV_128, and the minimum VCO multiplier, and the maximum MultiSynth divider, it is possible to get down to 3.5kHz with an Si5351A with 27MHz reference. So 2200m band is easily feasible.? 73 Hans G0UPL On Mon, Jul 16, 2018 at 4:59 PM joe price <joeprice@...> wrote: Bill, |
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Re: Si5351A VFO/SigGen I2C Hardware question
#vfo
Hi Bob, Michael In the beginning (or at least closer to the beginning) was the Ultimate QRSS/WSPR kit? with a crystal oscillator whose frequency was pulled by an LED acting as varicap diode.? Next came the Ultimate2 ?, which used the Chinese AD9850 DDS modules as the oscillator. Next came the Ultimate3 , with the much-improved display, which can operate in 4-bit mode and therefore made available more I/O pins which were used to drive the relay-switched LPF kit, providing coverage of up to 6 bands in a sequence of transmissions.?? Things went fine with the Ultimate3 - theories abound as to why the Chinese AD9850 DDS modules were so cheap. My theory is a limited black-market stash of non-RoHS chips, which factories bought-up and made into the modules for sale on places like eBay etc. In any case, after QRP Labs customers had chewed their way through around 2,500 of these Chinese AD9850 DDS modules the price had doubled to more than $8. Just checking now, they are up over $14! So making Ultimate3 kits started to get? a) difficult (it was hard to find suppliers for hundreds of AD9850 DDS modules at a time b) uneconomic, as the price was going up and up... This was around end of 2014 by the way.? That was when I designed the Si5351A Synth module . It was designed in such a way that the module had the same 2 x 10-pin headers that the AD9850 DDS module had, and was to an extent, pin-compatible! Although the AD9850 is programmed by loading a tuning word in serially, and the Si5351A is very different, with I2C communication and a more complex configuration - if the AD9850 DDS module had been used with serial programming (as was the case in the Ultimate3 kit), then with only firmware changes, my new Si5351A Synth module could be a plug-in replacement in some cases. Yes there are other differences too, such that the AD9850 DDS has a sinewave output as well as a squarewave output, whereas the Si5351A has three separate output frequencies.? (Actually I missed out of the story, that I actually spent months developing the OCXO version of the Si5351A kit first during Summer/Autumn 2014, see - BUT, at a certain point I realized that it is quite tricky to build, and would increase the cost. And anyway in most cases the extra stability isn't needed. So then I quickly developed the very simple basic Si5351A Synth kit so that for the vast majority of constructors there would be an easy solution which also did not increase the costs).? So the original idea was that the Si5351A could be plugged into an Ultimate3 kit with no other changes than a firmware version capable of using it. I wrote the firmware such that it could auto-detect whether an AD9850 DDS was plugged in, or the new Si5351A Synth kit, and would communicate appropriately.? This *almost* worked, but unfortunately the 3.3V squarewave output of the Si5351A was less than the 5V output of the AD9850 DDS module, and this meant that the Ultimate3 PA produced only about half the power output when an Si5351A module was used. Since that could upset many people, I made a few changes to the PCB, to accommodate the bias trimmer potentiometer and capacitative coupling between the Si5351A output and the BS170 gate. That allows a DC bias to be established at the BS170 gate which restores the power output. This new PCB was called the Ultimate3S and introduced in January 2015. In fact the power output of the Ultimate3S exceeds the Ultimate3, and particularly so at higher frequency bands. There are other advantages too, in that the Si5351A can reach 6m and up, whereas the AD9850 DDS was limited to not higher than 10m band. The Si5351A module also has better frequency stability.? Because of the BACKWARD COMPATIBILITY requirement, that the Si5351A module should be able to slot into an Ultimate3 kit instead of the AD9850 DDS module, I had to re-use the same I/O pins of the microcontroller which were used for communication with the AD9850 DDS chip. Unfortunately the AVR's TWI (same as I2C) peripheral pins 27 and 28 were already in use. So to make it all happen, I had to develop a software-emulated I2S peripheral, so the AVR could talk I2C on the pins it had been using to load data into the AD9850 DDS chip.? The firmware development continued for more than a year until April 2016, with the same firmware version supporting both the Ultimate3 and the Ultimate3S. It was important to me to keep the owners of the older Ultimate3 kit happy and not force them to upgrade to a new Ultimate3S kit. So that was successful for quite a while, but in the end it became impossible to fit in any more functionality and so I had to stop the support for the older AD9850 DDS.? Back to the original questions - there is nothing wrong with the AVR's TWI (I2C) peripheral and I would have loved to make my life easier and use it, if it had not been for the backward compatibility target. The AVR's TWI is ONLY available on pins 27/28, it does not have the capability to route these to different pins. In the QCX kit I use the AVR's TWI directly (pins 27/28).? The sharing of pins is something I do a lot, because the number of I/O pins on the ATmega328 is less than I needed. So I had to find ways to multi-purpose the available pins. Of course I could have used a larger processor but one of the strong principles of QRP Labs kits is to do less with more, in proper QRP spirit... to keep the costs as low as possible. The I2C bus ignores the SDA (data) signal unless there is a transition on the SCL (clock) signal. So we are free to use the SDA signal for other purposes, in the case of the Ultimate3S, for communication with the LCD. The LCD also ignores what happens on its data signals, until you toggle its "EN" signal. YES... I know, pin 27 (PC4) is free, according to the diagram, however I necessarily had to use, for the Si5351A, two of the three signals which were used to communicate with the AD9850 DDS.? There was another interesting spin-off to the story, which was that I had manufactured 640 PCBs for the Ultimate3, just before realizing that the lower 3.3V squarewave from the Si5351A wouldn't drive the BS170 as hard, halving the power output. Then I modified the PCB layout and made another 640 PCBs now called "U3S", with the bias trimmer pot. In order to make myself less unhappy about wasting the 640 U3 PCBs, I created the Clock and VFO/SigGen kits. These work with the same basic kit as the Ultimate3/3S, of course they don't need the bias network so they were Ok on the old board. So that little problem motivated the spin-off Clock an VFO kits, which have subsequently been very popular in their own right.? 73 Hans G0UPL On Tue, Jul 17, 2018 at 12:03 AM Bob Macklin <macklinbob@...> wrote:
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QCX Enclosure / Case Connector? Ideas . . . .?
Hi,
Have had my qcx case for several weeks, and i really enjoy it better than the ideas I've used until this point.?? Question regarding the opening just above the gps connection on the rig when installed.? What ideas has everyone come up with for a bulkhead / pass-through connector which fits that hole?? The serial type I have have all been too large.? I tried just passing the wires through but created a short.? Thought I fried my rig; luckily as soon as I removed the worn wire the rig went back to business as usual. |
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Re: QCX and electronic keying
Bob Macklin
¿ªÔÆÌåÓýThe Heathkit keyers are made for Heathkit's GRID BLOCK keying.
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They switch a NEGATIVE voltage to ground.
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Bob Macklin
K5MYJ Seattle, Wa. "Real Radios Glow In The Dark"
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Re: QCX and electronic keying
Tony Goldsworthy
The QCX keying requires a 3.5mm stereo bullet plug. For straight or bug semi auto keying connect to the tip and the body of the plug. Leave the second ring unconnected. And you'll be right!? On Tue., 17 Jul. 2018, 09:46 , <cwebs@...> wrote: I have two Heathkit electronic? keyers and wonder if they can be used on the QCX. I ask because it will work on my Heathkit SB 104a and Kenwood TS 820s but will not work on my Icom 740. The Icom takes a three way plug for use or a straight key or paddle style key but will not work if I try the electronic keyer using straight key contacts. Icom has iambic hardware installed. I can't test yet because my kit is on order. Thanks Carl |
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QCX and electronic keying
I have two Heathkit electronic? keyers and wonder if they can be used on the QCX. I ask because it will work on my Heathkit SB 104a and Kenwood TS 820s but will not work on my Icom 740. The Icom takes a three way plug for use or a straight key or paddle style key but will not work if I try the electronic keyer using straight key contacts. Icom has iambic hardware installed. I can't test yet because my kit is on order. Thanks Carl
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Re: Si5351A VFO/SigGen I2C Hardware question
#vfo
Bob Macklin
¿ªÔÆÌåÓýWhat you guess about the SDA/SCL lines is correct.
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I'm just wondering why so many people avoid using the I2C(TWI) interface as designed.
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I'm trying to learn how the Atmel I2C/TWI interface actually works.
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But right now I am trying to repair my ENGINEERING computer. Several hard drives have died (from age I think) and I need to buy more modern drives.
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Bob Macklin
K5MYJ Seattle, Wa. "Real Radios Glow In The Dark"
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Re: Si5351A VFO/SigGen I2C Hardware question
#vfo
It looks like Hans needed PC5 (normally used for SCL) for the IPPS interface to the GPS module.
Maybe he can comment on why the hardware wiring ended up as it did. I am sure he had a very good reason for this.? Also i noticed the PD2 (physical PIN4) on the ATmega328 is connected to both D6 on the LCD (which is not using I2C) as well as SDA on the Si5351a. This is also confusing.? I am guessing that maybe the?Si5351a ignores anything on the SDA line without? the clock (SCL) signal being present so that allows PD2 to serve a dual purpose ? Cheers Michael VE3WMB? |
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Re: Ultimate 3S Keeps Blowing Finals
¿ªÔÆÌåÓýHi Todd: Are you getting the once-per-second heartbeat ok? Roger G3YTN ---
**
Roger Hill ** On 2018-07-16 16:19, Todd Christell wrote:
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Re: Si5351A VFO/SigGen I2C Hardware question
#vfo
Bob Macklin
¿ªÔÆÌåÓýI don't understand why no one uses the I2C port the way it was intended?
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Bob Macklin
K5MYJ Seattle, Wa. "Real Radios Glow In The Dark"
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Re: Ultimate 3S Keeps Blowing Finals
Hi Al (et al):? Had time to put my 3S on the bench and got some interesting results: Old FET (the one I thought was bad) Idle current: 68 mA Transmit current: 240 mA Output voltage 3.63 volts (on an old version of the Hendricks 50 ohm dummy load so maybe ~200 mW) New FET Idle current: 68 mA Transmit current: 230 mA Output voltage: 3.48 volts Two net FETs Idle current: 70 mA Transmit current: 323 mA Output voltage: 6 volts (~400 mA) Still no contacts Conclusion?: It appears that my FET is/was OK. It may have been coincidence that after I replaced it the first time I started logging contacts. Ran my antenna system on the analyzer and everything looks OK. The only thing I can think of now is either something wrong in my configuration or possibly a timing issue. I have the GPS unit and it is showing good satellite lock. I was also a little surprised that the 40% increase in transmit current gave me a 72% increase in output power.?? So, I will start looking at configuration and calibration.?? 73, Todd AD0RR On Tue, Jul 10, 2018 at 2:33 PM, Al Holt <grovekid2@...> wrote: Another question is how warm does the BS170 get during the 2 minute WSPR cycle? I tend to worry about them getting too hot if operating with high a duty cycle. --
"When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exup¨¦ry |
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Re: Si5351A VFO/SigGen I2C Hardware question
#vfo
With some more digging, I think I found an answer to my own questions.??
I discovered an Arduino library called SoftI2CMaster/SoftWire. The the SoftWire interface, which mimics the built-in "Wire" library allows you to use alternate PINs for the TWI (i2C)? interface using a software implemented protocol rather than the hardware assisted TWI interface used by the built-in Arduino Wire library.?? Using SoftWire with the proper defines should allow me to port my existing code with minimal changes.? Cheers Michael VE3WMB? |
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Re: Testing QRP Labs Si5351A Synthesiser Module, PCB Rev 4
Bill,
? I used the test file under example 3 (Si5351a-test.ino) worked OK for me. However I also could us Arduino help adding 136 and 474Khz I lowered the frequency from 1Mhz to .1 that allowed the vfo to tune thru the 630meter band but not 2200 meters I know the divider needs to be changed but can't find it so I anyone knows help would be appreciated. (my interest is using the vfo on 630 and 139Khz? Thx? ?Joe? ?wa9cgz |
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Re: Wood: the other case alternative.
#case
I guess that means you're not an Old Dog, but maybe a Mast-odon? :)
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Si5351A VFO/SigGen I2C Hardware question
#vfo
Looking at the schematic for the Si5351A VFO/SigGen kit, I was surprised to see that on the ATmega328 that PB1 (physical pin 15) is being used
for SCL and PD2 (physical pin 4) is being used for SDA for the I2C interface to the Si5351a chip. I had always assumed that there was something special about PC4 (physical pin 27) and PC5 (physical PIN 28) which is why they are? used for SDA/SCL.? So am I correct in assuming that the designation of which pins are used on the ATmega328 for I2C is simply a function? of the software used or are there any other hardware considerations or limitations ?? My intent is to hijack the hardware on one of these VFO kits to make it do my own bidding. I have existing Arduino DDS VFO code that supports the Si5351a and I recently picked up an Adafruit Boarduino USB kit which will allow me to program a socketed ATmega328 using the Arduino IDE (the Boarduino looks like an Arduino Nano to the IDE), My plan is to port my existing?code to? the QRPLabs VFO hardware. I will program my own ATmega328 and install it in place of the pre-programmed one supplied?with the kit.? My assumption is that I am going to need to find a different I2C library other than the built-in? "Wire" library for the Arduino, that will allow me to reassign the PINs used for SCL/SDA.? Cheers Michael VE3WMB? |
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Re: Help with QCX20
#qcx
If you haven't already, start working through Hans' QCX Troubleshooting guide from their website in the 'QCX area.'
I think one of the first things to look for now that the 'smoke is out' is the component(s) that let it out, the ones that failed. Also, a very detailed and close up inspection of the board for solder blobs and any stray component leads that might be shorting out. From what I understand, having 'two rows of squares' usually means the microprocessor is having troubles communicating with the Si5351 chip. But, if you have an earlier revision board (3 and below) then you should do the recommended mods. If you need to remove components from the board, it's better to sacrifice them and not the board. Removing individual leads with a hemostat, heat and gravity works very well. Clean up through hole with Solder-Wick and/or a toothpick. Good luck with the repair! --Al WD4AH |
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Re: QRP Contes
I am glad to hear that. Looks that the gap has widened though. and even outside the contests there are more stations even with not so special calls that are just throwing 5nn around instead of a true report and at least giving name and QTH.
I never have been on the level of chatting extensively even at medium speed but liked the standard info in my log.? Anyhow any contest is a good way to test out how QRP works as if they hear you they want you in the log. Also the band seems open all of a sudden but I think its simply otherwise no one was there. 73 Martin |
Braden Glett
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