Wednesday, January 27, 2016

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:

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.

Tuesday, January 19, 2016

Arduino UNO, SI5351A breakout as 50MHz CW beacon

Been playing around with a $39USD Arduino Kit I bought from 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.

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

The code for the Arduino came from here:

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: (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

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.

Thursday, January 14, 2016

Airspy, Spyverter, Hermes, and HackRF Using Leo Bodnar GPSDO

Leo Bodnar has developed a VERY NICE Clock Reference (I would call a GPSDO) which I recently purchased from Force12Inc they sell two of them this one, and this one (with a custom low phase noise xtal).

The Airspy SDR accepts a 10 MHz clock input.  I've been using mine until recently in a modified manner where I used the ADC1 direct input (which bypasses the on board filters, and AGC) to input the 9 MHz IF output from my Yaesu FTDX-5000.  I didn't really like this method since it bypassed some important areas when there are strong signals on 50 MHz.  It would frequently overload the Airspy (which I love btw), so I have a 30dB step attenuator in line to help control this easily.

Anyway, now that the Spyverter is available, (and it's a VERY VERY nice upconverter) I wanted to try to go back to a more standard method of getting the 9 MHz IF out into the Airspy.  Unfortunately the Spyverter (even the TCXO version) suffers (slightly) from xtal drift.  I discovered this immediately as this was the reason I had abandoned use of upconverters in the past.

I emailed Youssef from Spyverter asking him if he was aware of a work around for the drift issue.  I'm 99.9% of the time a CW operator, and this drift means that I'll be close, but NOT ON when I click on a CW signal in HDSDR.  Depending on the drift of the moment.

He mentioned that they had tested removing the xtal on board, and feeding 120 Mhz clock from a Leo Bodnar Clock Reference into it instead.  Leo's nifty little reference has the ability to create TWO output clock references at the same time from one GPS antenna connected to it.  I had it working providing 120 MHz and 10 MHz output within about 5 minutes after it arrived in the post today.

It took me about an hour (CAREFULLY) removing the on board xtal on the Spyverter.  I really don't recommend doing this the way I did it.  In fact if you plan to do something like this I'd recommend contacting the airpsy/spyverter folks and ask them for a board with no xtal on it at all.  It's NOT EASY, and in fact I feel lucky to have managed to get it removed without damaging the board or components.  I suppose if I'd had a SMT de-solder station it would have been simple.  But I don't.

Here are some photo's of how I accomplished this in my setup:

Right side SMA is the new one I added

After this is all done it's ready to test.  I attached the 120 MHz reference line from the GPSDO to the new SMA port on the Spyverter, and connected everything else up normally.

When I was done, I started up HDSDR and discovered that when I went to calibrate it all, it was spot on.  

I didn't need ANY offset at all.  


So now I'm just testing things to see if there will be any drift noticed.  So far I haven't seen any at all.  

UPDATE Jan 24, 2016:

It's now 10 days later since I set this up.  Frequency hasn't drifted in any noticeable way at all.  I'd call this success.

Saturday, January 2, 2016

New/OLD Power Line Noise 2016-01-02

The past few days it's been cold and dry here in Missouri.  Seems a new crop of power line noise likes to start up in these conditions.  From my QTH it peaks about 50 degrees.  When I turn off the internal preamp and use IPO1 I can just detect it on the S meter.  When I use Amp2 on the FTDX-5000 (preamp #2 on) it's about S9.  

The weather has been COLD around freezing (31F as I write this), and very dry atmosphere the past 3-4 days.  Skies are mostly clear.

Here's what it looks like in HDSDR (AM MODE)

Note (STRONG 120Hz and harmonics 180, 240...)

Here's what it sounds like:

After some review of Google Earth, and some drive testing I've found a line of poles that seem to fall in the correct azimuth (50 Degrees from my tower).

Here are some pictures of the poles I've ID's so far.  The poles with numbers shown above exhibited ULTRASOUND (40 KHz) arc'ing noise as well as 400 MHz Power Line Noise (AM) during this drive test.  AM 1.7 MHz also had a VERY STRONG (ON/OFF) Power Line Noise exhibited as well, however, I was unable to track that one down due to it's nature.  It sounded like some sort of ON and OFF semi-randomly.  It's unrelated to the primary noise I was tracking down in this drive test though.  (I'll revisit that one soon).

Pole # 570236

Pole# 570252

Pole # 570244

(Ultrasound TOP insulators, road-most was the worst)


  1. Attempted to contact Ameren UE (800-552-7583) @ 2:26PM 2016-01-02 however they're not available during non-business hours for non-emergency issues.  I'll try again 2016-01-04 on Monday.
  2. Contacted Ameren and filed a report/complaint 2016-01-04 12:30PM.  I forgot to get ask for the dang ticket number.  So we'll see how this goes.  Normally they send a service truck out within a few hours to discuss things, and then within a few weeks the RFI team arrive, then a few weeks later they start work on repairs.   So first person I talk to I'll get the ticket number.  Or I'll call back and get the number.  
    1. The last time I called in a request like this it got a little messed up on their end.  I was told they were in process of changing staff and their procedures at that time, so hopefully this will go more smoothly this time around.  Ameren has ALWAYS been very responsive, it's just a matter of being a little bit patient with them.  They've always been very curtious and understanding in the past.