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TinySA construction
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Erik is still doing great engineering and education on this project.. THANK YOU AGAIN ERIK! Gary |
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Should be able to put it all down on a single pc board,
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including sockets for Si4432 modules and a processor. As per the end of post 595. I'll probably build something manhatten style once my modules arrive. Chuck Adams in the old qrp-tech group recommended a sheet metal punch and CEM type PCB material: ? ??/g/qrp-tech/message/5839 ? ??/g/qrp-tech/message/13389 The CEM material is much easier on the punch than FR4. Google "Hand Held Power Hole Punch Set Sheet Metal? Die Aviation Heavy Duty" for the punch. Another option for prototyping is to use a spot weld drill bit such as this: ? ??/g/BITX20/topic/68158902 Available in 3/8" and 5/16" sizes. Can be used to cut copper islands into a PC board, or press harder and get a manhatten pad. Rectangular pieces of PC board are often used to create boxes for shielding. Though I wonder if small hunks of thin walled copper pipe might be easier. Ideally, socket the shields into the board so they can be popped off to work on it. Or if low enough, just take off a top cover of EMI gasket material. If all the compartments are the same height, could be just one big cover. But I don't have any experience with what kind of shielding works on something like this. My cellphone works, and that's full duplex into a tower 40 air miles away. So if you know what you are doing, it's apparently possible to? have something well shielded but small. On the other hand, in building his spectrum analyzer, W7ZOI laid out each section to fit into a Hhammond 1590b die-cast box:? ?? The thing about SMA connectors everywhere is you can easily swap stuff in like extra gain just to see what happens.? But if this thing works well and is easily duplicated for $20 in parts, somebody should?make a PCB. Jerry On Wed, Jan 1, 2020 at 05:56 PM, wb6ogd wrote:
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Looks very good.
Why not add the pe4302 attenuator chip? Can be found on ebay for less than 1$/pcs -- HBTE Files section:?/g/HBTE/files Erik, PD0EK |
开云体育good idea!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 email:??bill@... ? On Jan 2, 2020, at 3:09 AM, erik@... wrote:
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Niels,
That may work as is. Or it may need a few iterations of the layout to work well at these frequencies. A few things I'd be scratching my head about: How solid is the ground plane??? Can the receive path from SMA to Si4432 be optimized for a short and straight path? from one end to the other to minimize coupling between elements (perhaps using coax for the LO from the second Si4432 to the mixer)? Should the longer high frequency traces be fatter to better approach the 50 ohm system impedance? Will noise from the Arduino overwhelm what you are trying to see? Can the circuit elements be broken up to allow for shields to be added? Should there be a series inductor added between the two SAW filters? Jerry |
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Jerry Ponko AC9NM
开云体育
I've been wondering about noise from the Arduino as well. I'm working on a Kicad pcb layout and thought the Arduino pro mini 3.3V, 8MHz version would work best since it doesn't have a USB connector which can be a source of noise. I plan on using sockets for everything including the PE4302 attenuator module. The SAW filters I just ordered from Germany so I don't know when they'll arrive but I would like to make a module out of those too. I guess there will need to be some shielding around the Si4432 modules and Arduino and plenty of bypass capacitors on power lines. Since I've never built a SA it's all experimental for me. As for the SAW filters, the coupling between them is probably ok as the are in series so whatever impedance they are will be matched. Eric seemed to imply that the matching inductors and capacitors are not that important in his build article. However, if you take the modular construction approach, you and try out different variations to see which works best. Jerry Ponko AC9NM On 1/2/20 1:00 PM, Jerry Gaffke via
Groups.Io wrote:
Niels, |
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Two capacitive ports in series makes for a really capacitive connection there.
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These SAW filters are not designed for that, as post 666 has shown. They need a conjugate match, which means adding inductance to each port to cancel out the capacitance.? A bit of physical separation between the two SAW filters might be a good thing, keeps out of band signals from jumping across.? Shielding one SAW filter from the other could also help. Jerry Gaffke, KE7ER On Thu, Jan 2, 2020 at 06:03 PM, Jerry Ponko AC9NM wrote:
As for the SAW filters, the coupling between them is probably ok as the are in series so whatever impedance they are will be matched. |
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Hi all, ??? I think that my experience of using screening with the Arduino NANO might be of use: Working with Tony Fishpool I recently built an attenuator using the parallel non latching version of the PE4302 module. This and an LCD display is controlled by a 5 volt version of the NANO. ??? I found that the attenuator output had 16 MHz? and all its harmonics up to about 800MHz on it! This seen on a Cushman CE-15 Spectrum "monitor", which for my purposes will do as a spectrum analyser.? These were at low level: mostly around -60 to -80dBm, and disappeared into the noise floor of the analyser? at 800MHz. ??? For some applications this would not matter, but for our current purposes it would be? a disaster! ??? The correct approach would have been to screen the Arduino and the display, but in a unit already built it was easier to completely screen the attenuator, which I did. ??? Ater that although the 32MHz Output was still there at about -80dBm, and there was a few outputs in the region of 100MHz at roughly -100dBm everything else was below the noise floor. ??? Of course I realise that other things can come into this - layout, wiring and decoupling for instance, and you may be lucky, do be aware that it could happen to you! ?? By the way; ???? I have not started on my analyser yet. I am still waiting for deliveries from China. I have just received the filters from Australia though, and intend to do the tests under discussion on another thread. If my results are different I will report them there. Tony (G3PTD) |
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Ok, its been a month or so, how are those tinySAs coming?
I am ready to build my next version.. the first is quick and dirty, see attached photo. It works beyond expectations for the quick and dirty construction! Does anybody have a PCB designed yet. I built the first with ebay modules, I think I want to try raw components on pcb next.? With shielding. I have modified a Arduino Nano for 3.3V, was easy and seems to work ok at 16MHz still... though I am not totally sure. Oh, do want a tracking generator too.. 73, Gary WB6OGD |
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I assume that tracking generator need only do up to 250 mhz.
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An Si5351 should be fine, spec'd for 225mhz, but does up to 290mhz. The tinySA will ignore any harmonics from the square wave.? Jerry On Tue, Feb 4, 2020 at 12:30 PM, wb6ogd wrote:
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开云体育Erik already demonstrated using a Si4432.He just said to use another mixer and use the LO to do the sweep. ?I think it would ?need a peak hold or something on the display though? 73, Gary? WB6OGD? On Feb 4, 2020, at 5:02 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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The Si5351 is a $1 part. common, very small, does 4khz to 250mhz,
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lots of DIY projects are already using it with Arduino boards. Not clear to me how two additional Si4432's and a mixer are better. Though if you are mass producing tinySA's, it is cool that one of them can be used as the tracking generator.? Jerry On Tue, Feb 4, 2020 at 05:10 PM, wb6ogd wrote: Erik already demonstrated using a Si4432. |
开云体育Jerry,Yes, Si5351 is an excellent part, I have several. Another Si4322 programmed to TX at the IF (434MHz) feeding a mixer... and the LO feeding the 2 mixers will make a great tracking oscillator. 73, Gary WB6OGD? On Feb 4, 2020, at 6:43 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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Ah, you're right.? One additional Si4432, not two.?
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? On Tue, Feb 4, 2020 at 08:26 PM, wb6ogd wrote: Jerry, |
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On Tue, Feb 4, 2020 at 08:26 PM, wb6ogd wrote:
I tried and the 433MHz did deafen the RX SI4432 You can test by disconnecting the RF input from the RX SI4432 from observe if there is still a zero Hz peak. Only with VERY good shielding will a tracking generator that uses a static LO at 433MHz work ? -- HBTE Files section:?/g/HBTE/files Erik, PD0EK |
开云体育Thanks Erik..? I was assuming good shielding..? Do you have a recommendation?Two more Si4432s?? That's only $3 and two more nSel pins, minor Arduino code. Or just a noise generator I already bought the parts for.. If I can only find them around here... 73, Gary WB6OGD On 2/4/2020 10:54 PM, erik@...
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On Tue, Feb 4, 2020 at 08:26 PM, wb6ogd wrote: |
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You can output the LO and send it to a completely separate fully shielded tracking generator box with a mixer, SI4432 and any micro to setup the SI4432.
LO from tinySA to RF port of mixer, internal SI4432 in TX mode to LO port of mixer, output of tracking generator box from IF port. You may consider to add an amplifier after the mixer but the IF output of the mixer can deliver from zero Hz and adding an amplifier (with its capacitors) will create a lower frequency output limit. Even the leakage through the tracking generator mixer into the LO port of the tinySA leaking into the tinySA RX SI4432 may be a problem causing reduced sensitivity. So indeed using a separate box with two SI4432 and a mixer being slaved to the scan of the tinySA may be better. -- HBTE Files section:?/g/HBTE/files Erik, PD0EK |
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Speaking about shielding: Did anyone find a source for shields on ebay, aliexpress etc? Whatever search quires that I use I get 0 results. Can't find any on?LCSC either. On Wed, 5 Feb 2020 at 16:36, wb6ogd <garywinblad@...> wrote:
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