PI7SIX/b

I was in a rush when this video was made.  Sorry for the poor quality.

Etherkit Si5351a GPSDO Driven (25 MHz) TXCO replaced

On Sunday I finally got around to modifying one of my Etherkit Si5351a boards to use my Leo Bodnar GPSDO by replacing the 25 MHz TCXO.

I just used a bit of scrap copper-clad PCB and an edge mount female SMA connector and a short bit of high quality coax (about 1 inch) to jump from the connector to the input where the TCXO was mounted.

The result was a super stable output from the Etherkit Si5351a without any further modification.  

It's been my experience on two different Etherkit boards that the TCXO is fairly drifty even with mild temp changes.  In addition for some reason it sometimes 'jumps' about 10-20 Hz randomly (too frequently for my taste often multiple times in 30 seconds) which makes for some wonky resultant CW (Morse code).

Arduino, TinkerKit, Etherkit Si5351a Multi-band Beacon (5-bands)

I was able to get this project all assembled and stable now.  It's boxed in a rack-mountable case now too.  I've added it's own power supply.  So it just requires 120vac from a wall socket, and an antenna connected to it to operate all on it's own.

Here's yet another demo video of the current running system.

It's currently running on the following frequencies:

• 10m: 28.208.35
• 6m: 50.069.73
• 2m: 144.278.75
• 1.25m: 222.055.70
• 70cm: 432.312.65

http://blog.dxers.info/p/arduino-multiband-beacon.html

Arduino, TinkerKit, Etherkit Si5351a Multi-band Beacon

So I've been continuing to improve and expand the little beacon project I've been working on as a winter project this year.  

The beacon is now capable of autonomous operation on 4 ham bands 50 MHz, 144 MHz, 222 MHz, and 432 MHz.  It's also able to operate on 902 and soon 1296 as well.  However, I'm awaiting funds to obtain a few more circuit parts needed to make those autonomous in the same loop it operates on now.  I've already figured out and tested 902 MHz.  

The code is fairly simple for the Arduino and the new Tinkerkit Shield, and Tinkerkit mosfet.  The mosfet turns on and off a 12vdc relay which switches the output of the Si5351a between two RF paths currently.

When I add in 902 MHz and 1296 MHz I'll need yet another relay to accomplish that.

These 12vdc relays are fairly cheap and can be found on Ebay for < $20 each.  They're good for about 1 million relay cycles per DowKey.  Which in the loop I'm using would give about 2 years of life if they last that long, or more if they extend past that. 

I will eventually replace these RF relays with something that has a longer life span, but for now and for this simple small beacon project this is acceptable considering they're price I think.

Anyway above is a video that shows all of this action.

I am using 3 SDR radio's to demonstrate the beacons operation so that you can see how the 'loop' operates from one band to the next.

The CW being generated is 30 wpm (words per minute) which is fast for a beacon, and I'll likely slow this down to 24 wpm.  But for the sake of a shorter demo I sped it up.

The single antenna being used is a simple 25 MHz to 1300 MHz Discone antenna.  The output power is approximately 100 mW (milliwatts).  These antenna's can handle a fair amount of RF power and they range in price but most are < $100 USD.

I have a small 1.5 Watt RF amp (shows in other video's on this blog) which operates from 0-500 MHz fairly flat across that range.

I've also ordered a similar 1.5 Watt amp that operates from 800 MHz to 1300 MHz and will be used in the 902/1296 section of the beacon.

Once those are added into the loop this will be a 6-band beacon all being run from a single Arduino and Si5351a (with various frequency multipliers).

http://blog.dxers.info/p/arduino-multiband-beacon.html

Arduino UNO, SI5351A breakout as 902MHz CW beacon

Today I decided to try to get this little beacon project up to 902 MHz, lo-and-behold it works. :-)

During the test I had forgotten I had two 15db pads (total of 30db) on the IF going into the mixer.  Since the signal was so weak with that, on the RF output side, I added a 0-500 MHz 1.5W RF amp before the final Frequency Doubler.  Which worked.

However, after this video I removed the 30db of attenuation, and the RF amp, and it was quite strong.  

Still this is a decent demo.

I also show how the almost raunchy 25 MHz TCXO.  I hate TCXO's.  My plan is to remove it, and use a 25 MHz GPSDO and that issue will be gone.  NOBODY likes a drifty beacon.

While it adds expense to the project, it's something I can test with a GPSDO I have on hand...once I've verified it resolves the problem, I'll order another (since I already use my current GPSDO in other projects).

Anyway here's the video of today's 902 MHz Beacon test.

http://blog.dxers.info/p/arduino-multiband-beacon.html

Arduino UNO, SI5351A breakout as 432MHz CW beacon

So as mentioned in an earlier post *here* and *here* what I suspected was true, I am able to get to 432 MHz with just a few addition components.  A Mini Circuits MK-3 Frequency Doubler, and a ZX05-1L-S 2-500MHz Mixer.

As shown in the photo above the Frequency Doubler goes at the CLK0 port of the Si5351a Etherkit Breakout Board.  I set that for a CONSTANT 150 MHz out carrier behaving as an "LO".  Out of the Doubler it comes at 300 MHz and that runs into the LO port of the Mixer.

I then set the beacon code in the Arduino Uno to generate KEYED 132.312.5 MHz on CLK2 port and that runs to the IF port of the Mixer.  The sum of the two = 432.312+ MHz output.  That runs in the photo to a 100 MHz High Pass filter and into a ZHL-1A-S 1.5Watt amp.  That then just runs to a dummy load that's sitting on top of a HackRF One with a wire plugged into it's antenna port a draped over the dummy load just so I can verify the output is where I think it should be.

Here's a video of it operating:

• http://www.minicircuits.com/pdfs/ZHL-1A+.pdf
• http://www.minicircuits.com/pdfs/ZX05-1L+.pdf
• http://www.minicircuits.com/pdfs/MK-3.pdf

http://blog.dxers.info/p/arduino-multiband-beacon.html

Arduino UNO, SI5351A breakout as 144 & 222MHz CW beacon

I've been working on ways to extend the use of the Etherkit Breakout Board & Arduino CW beacon I recently posted about *here*  

I want to TRY to do UPCONVERSION where I use CLK0 as an LO frequency (on the Si5351a) and CLK2 as the IF frequency through a cheap Mini Circuits frequency mixer.  I had in my junk box model number ZX05-1L-S+ which has SMA connectors and covers 2-500MHz.

You can see in the photo above how this is connected.  The coax trailing off the right of the pix goes to a dummy load in this video below which is just resting next to a HackRF One and the beacon above reception is being shown via HDSDR.

So CLK0 (the top connector off the Si5351a) in the photo above is set to 94.208 MHz (and change) and CLK2 (the bottom connector) is set to 50.069.75 MHz.  The resulting output from the Mixer is the sum of both and equals 144.287.75 Mhz (more or less it wasn't all warmed up when I made the video).

Now just to be fair the Si5351a can output up to nearly 160 MHz so this isn't really necessary for 144 MHz.  But it was a starting point.

The next band up is 222 MHz, so all that is needed to change in the Arduino sketch is to change CLK2 to output at 127.847 MHz and presto the output from the mixer is at 222.055.75 MHz.  This works too!  I didn't have time to video it in time to post this blog, but it works the same way.

So at this point this beacon could operate on any HF band, 50, 144 and 222 MHz as well as is.

This mixer can go as high as 500 MHz.  So in theory I could get up to 432 MHz with a setup like this, except that the Si5351a's max output frequency = 160 MHz.  160 x 160 = 320 MHz would be the max in this configuration and that's just not enough.

However, I also have a MK-3 Frequency Doubler :-)  It requires a fairly high input and there is about 13db loss in the conversion.  So a amp will likely be needed to do this.  Just so happens I think I have just what I need for that too.  I've been muxing around with little RF projects for quite a few years, and the junk box is full of things like these.  

So that'll be my next post as I work on trying to make that a reality.

---------------

The reason I'm trying to do this, this way, is that I would like to make a beacon that can operate on as many bands as possible and programatically (within the Arduino Sketch) change bands and 'beacon' on each that it's capable of on a timer.

Really this is just something to do while it's too cold outside.  I'm not sure I'll ever really put something like this on the air.  But it's a lot of fun and combines a lot of things I've learned the past few years with these winter projects.

http://blog.dxers.info/p/arduino-multiband-beacon.html

Arduino UNO, SI5351A breakout as 50MHz CW beacon

Been playing around with a $39USD Arduino Kit I bought from Amazon.com and an Etherkit Si5351A.  Total cost of this project was about $55 with shipping.

In the demo above the Si5351A is outputting 2mA or -7dBm or 0.1995 mWatts. http://www.cantwellengineering.com/calculator/convert/mA

The antenna I used is just a 6" long piece of wire.  Nothing major there.

The code for the Arduino came from here: https://github.com/la3pna/si5351_beacon

With a few tweeks (just text message sent, and some timing and removal of a 30 second carrier tone), I had it running in about 10 minutes.  Frequency is very stable, I bought the TCXO version of the Etherkit.  It could be improved most likely by removing the TCXO and replacing that with a GPSDO freq reference.  Which should lock it without an drift at all.

About 30 minutes after I shot this video the carrier really got stable.  With no drift or wobble.

This is running at -7dBm or 2mA for this demo or 0.1994 mW

SI5351A: https://www.etherkit.com/rf-modules/si5351a-breakout-board.html (I bought the $15 version with TCXO)

* All SMT components assembled, 0.1" headers included separately

* Fully tested

* Output frequency range: 8 kHz to 160 MHz (see Constraints below)

* Number of outputs: 3

* Output impedance: 50 Ω

* Output drive levels: 2 mA, 4 mA, 6 mA, 8 mA (into 50 Ω)

* Power supply: +3.3 V or +5 V

* Interface: I2C (on a 0.1" header)

* Output jacks: 0.1" header or optional SMA female end launch

* PCB material: high quality 1.6 mm double-sided FR4 with soldermask and ENIG coating

* PCB dimensions: 30 mm x 50 mm

* RoHS Compliant

Constraints

Two multisynths cannot share a PLL with when both outputs are less than 1.024 MHz or greater than equal to 112.5 MHz. This means that you may only have two outputs under those conditions.

Arduino UNO kit: http://www.amazon.com/gp/product/B016D5KUHS?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

http://blog.dxers.info/p/arduino-multiband-beacon.html