Friday, February 27, 2015

A SIMPLE Voltage Variable Power Supply

I'm planning to include a 41db voltage-variable-attenutator in my HF Upconverter.  So I needed to build a tiny voltage-variable supply capable of 17vdc max down to 1.2vdc.  I discovered that using an LM117 was a nice way to accomplish this.  Since I needed something more than a voltage divider and it needed to have a fairly large range. 1.2vdc-17vdc.  

Input to this supply will be around 18-20vdc (I need to test what I need before I'm sure exactly)  I think there's about a 1.2vdc drop with the LM117 (something like that) so in my test feeding it with 13.8vdc output around 12.4vdc (from memory I didn't actually log it), but when turning the poteniometer all the way it went all the way down to 1.2vdc. 

The LM117 can accept as MAX input +40vdc [datasheet]

I simply followed the Datasheet for part values as a default.  Seems to work well.

Minus a few minutes to read the Datasheet, and solder the parts up this took about 30 minutes to build.  And seems to work JUST LIKE I HOPED.

I liked this so much I built a stand-alone Variable Power supply

Below is the start of a 13.8vdc INPUT and 1.2-38vdc @1.5amp Variable Power supply I've started building.  It's super simple to build this.  Takes just a few minutes with the right parts.
2 caps, 1 fixed resistor, and a 5k variable pot plus the LM117 and a tiny DC-DC BOOST converter capable of up to 40vdc output.  Input to the DC-DC boost in my case is a 13.8vdc supply that is common to a lot of things I already use in the shack.  Although it could be just about anything < 40vdc (approximately).

The LM117 max output is only about 1.5amp but this is more than enough for testing simple stuff in most cases (that I would be using something like this for).  Usually I'm trying to test a LNA and the mass of LNA's I have range from 5vdc to 28vdc all of them draw very few mA's.  So this is more than enough to use as a simple test bench variable supply for this.

This is a picture of the beginnings of my stand-alone supply.  I have a LOT of options I could incorporate with something like this, and probably will eventually.  I haven't added the DC-DC Boost supply to this yet, I had to order a second one since I already used the first one I bought.  These supplies only cost < $8USD on ebay.  The few other parts listed about are also < $8.00 for the most part.

I took the above pix after I was done testing one of my 5vdc LNA's

Space to the LEFT will contain the DC-DC Boost converter.  the LM117 is to the right with the small heatsink attached.  In this configuration I just connected it directly to the 13.8vdc regulated supply I meantioned earlier.  After I add the DC-DC Boost Converter it will connect to the converter, and the converter will then connect to the 13.8 vdc supply.

I could add a rotary switch with preset resistance with a bypass switch to the variable pot for convenience.  Then I could perhaps have presets of 2.5vdc, 3.3vdc, 5vdc, 6vdc, 9vdc, 10vdc, 12vdc, 15vdc, 20vdc, 24vdc, and 28vdc for convenience.  Just a matter of adding the switches, and some resistors.

I'll post more pix as this little project moves forward.

Thursday, February 26, 2015

Touchstone RF Spectrum Analyzer Software


I wanted to have a quick and simple view of a large bandwidth that's being sent into my RTL Dongle.  Basically I wanted to SEE how altering the various low pass, and high pass, and band pass filters in my 100 Mhz Upconverter affected the output being sent to the RTL Dongle.  I came across this video showing how Touchtone's "RF Spectrum Analyzer Software" (I used the FREE version) could be used with one of these dongles to get a sense of how a filter is functioning.

(this is NOT MY Video, but demonstrates what I wanted to do basically)

Seems to work well enough!  I can now see what I wanted to be able visualize.

This was BEFORE I added a FM Broadcast band NOTCH filter AFTER the Upconverter
and just in front of the RTL Dongle.  NOTE the spectrum shape just above 105 Mhz is similar to the Band Pass filter shape I have at the input to My Upconverter.  LO Freq of 100 Mhz is at -65 dbm

This was AFTER I added a FM Broadcast band NOTCH filter AFTER the Upconverter and just in front of the RTL Dongle.  Notice the dramatic different in spurs around the 100.0 Mhz LO frequency and also the LO is down around -89dbm  Also the very different shape of the pass band around 109-115 Mhz.

While this example didn't show me what I'd hoped for, it DID show me reality of how this filter affected the results.  SO the lesson learned here is that this is a FREE and USEFUL Tool if you are attempting to visualize the effects of filtering.

I think what I'm actually looking for is a NOTCH filter that stop hard around 102 Mhz, however, this sort of thing can be quite difficult to find.  I'm basically trying to minimize the LO as much as possible or at least get it to be lower than the pass band from 109-115 Mhz. 

Anyway, I just wanted to share this with folks in case anyone else is trying to visualize the effects of a filter.  Of course, the thing to do REALLY is to inject a wide band noise source into the filter, and measure the output using software like this.  By the way, the "Ham It Up" upconverter has a noise source built in (minus a few simple addon parts to activate it.  It's a cheap way to get a decent noise source however.

Sunday, February 22, 2015


First time I've done this so I can't swear to how well I thought it through or really any aspects of the entire thing LOL.  I'm trusting the design at this point.  The results on-air seem impressive though.

I wanted to see if I could clean up the output RF from the 9 Mhz IF out of the FTDX-5000 which then goes into my new HF Upconverter to help reduce images, and noise, and misc trash in the spectrum prior to upconvertion.

I went to CoilCraft and downloaded their "Low Pass Filter Designer" software (free) and designed a 7 Pole (7th Order Low Pass Elliptic) filter.  I ordered their inductors from the design directly from CoilCraft.  Then ordered the required Caps from Mouser.

Below is a screen shot of the design.

Following are some photo's of the constructions.  This was VERY difficult for me since I don't have tools to work with SMT parts that are the size of 4 grains of pepper!  Literally.

BUT I did manage to get it built, and after retouching some bad solder joints it seems to be working very well.  I plan to include a real plot from a VNA setup I have eventually.  But that'll be a while as setup for that takes too much time at this point.  

This is a strip of sticky copper tape 1" wide top to bottom, turned upside down so I could hold the Inductors in place while I tacked them with solder. (not pretty, but like I said it's not easy either without the proper tools)

This is some double sided copper clad PCB.  I trimmed away the copper on in the middle on both sides so as not to effect the inductors.  Then cut slots for solder pads to match the layout of the inductors I tacked together in the above photo.

Top side completed.  With caps added.

Bottom Side with Caps added.

Friday, February 20, 2015

HF Upconverter - Assembly and Initial Testing


After a few days or working on my new HF Upconverter I got it working!  I'd been waiting for some Buck type DC-DC converters.  So I could connect the OCXO (3.3vdc) up to the 13.8vdc from my primary Astron RS-35M.  One of the Buck converters drops 13.8vdc to 12.0 vdc, then a second one drops it again from 12vdc to 3.3vdc.  They seem to be working fine.  The 12vdc is variable.  The 3.3vdc is not which is kind of a bummer, but it's at idle on my Fluke meter 3.29vdc. (probably close enough although if I'm going to the trouble of an OCXO I'd like the PS's to be adjustable).  I'll probably hunt around for a Buck DC-DC 12-3.3vdc that is adjustable.  These things are CHEAP on ebay.  Total spent on both was around $15.00 combined including shipping.  Which beats spending hours building them at this point.

I am running the OCXO HF upconverter right now as I type this, and it seems to be rock solid so far.  No FM Bcast interference (which I didn't think I'd have with all the shielding).

I have a fair amount of work to do yet on this.  However, the fact that the SBL-1+ Mixer and the OCXO work as expected is definitely encouraging.

I am listening right now to 14 Mhz Morse Code on the FTDX-5000 and also on SDR# at 109 Mhz.  (remember the FTDX-5000 uses a 9Mhz IF Output that I'm tapped into, so the actual VFO frequency is irrelevant since all signals are sent out in the 9 Mhz realm.

Anyway...I just wanted to post that as simple as this is right now and working as well as it is, I can't wait to add the Lo and Hi pass filters to my Homebrew HF Upconverter that is accurate to within 200ppb (that's parts per BILLION)!  NO DRIFTING has been noted in my testing thus far.

Tomorrow I'll start it up from cold, and see if there is any noticeable.  I'll also post some updated pictures of where the project is now.

Things are subject to change until I setting on a mixer.  While the SBL-1+ works fine I'm curious how well the the other two I ordered from Minicircuits will work.  The are supposed to be better, and certainly should be at 4-7x the cost of the SBL-1+ (which was only $9.95).

This is FUN STUFF!

Thursday, February 19, 2015

100 Mhz OCXO 200ppb For Home Brew Upconverter

I still have some work to do on this.  The closest (bottom left) (pin 1) large pad get +1.15-2.15vdc via resistor network voltage divider that bridges over from the large pad behind it  (pin 14) that is the +3.3vdc Power Supply pin.

The SMA is the 100Mhz @ 200ppb output from the OCXO which comes off pin 8.

The resistor network I was talking about is a voltage divider in the standard configuration of R1 and R2 except that I've slightly modified it to include a 1-turn 1000 Ohm Potentiometer which should allow fine tuning the OCXO by as much as -500hz and +500hz.  Hopefully this won't be needed much as that the point of having the OCXO to start with, but it simplifies retouching tuning quite a bit and seemed simple enough to add (as long as my design holds up!).

There will be a KNOB on the front of this which allows easy access for tuning the OCXO to mate up with the signals on the 9 Mhz output of the FTDX-5000.  INSTEAD OF having to go into HDSDR software's option menu and extio menu to adjust things (WHICH DRIVES ME NUTS!).

I hadn't realized that I had to provide a Vcc for pin 1 initially, and at first when I discovered this I didn't really like the idea.  Still not sure I do frankly, BUT since it adds a feature I hadn't thought of to start with I figured why not make it something I can make use of, instead of simply setting pin 1's voltage to 1.65vdc which SHOULD place the OCXO at 0pmm/0hz offset from 100 Mhz.

This "feature" provides a much as 1 full Khz adjustment (I think, according to the doc's I've read).

Sunday, February 15, 2015

HF Upconverter - Home Brew (sort of)

(smoke testing components)

(Partially built, still working on final placement)

The TOP SHP-100A+ which is a HP Filter feeding the RTL Dongle is going to get replaced with a High Pass Filter I'm going to build.  My own filter will be VERY sharp and drop the 100 Mhz Carrier from the Oscillator down about 53db from where it is now, while leaving 107+ Mhz open.  My Filter will have about 5db insertion loss at 109 Mhz, but I'm also planning to add a LNA after the filter which will allow me to overcome that loss somewhat.

The Empty space top LEFT will contain a +20vdc DC-DC boost converter as well as a LM117 voltage variable regulator +17vdc to 1.2vdc to power a 41db voltage variable Attenuator and a pot will be added with a second knob to control it.

I'm also planning to add a PTT actuated RF Relay to switch out the RF input when my primary radio (and FTDX-5000 transmits) as I don't like the output of my Transmit via the 9Mhz IF output showing up in my Pan Adapter output.

The only dismal be at this point is that the Nooelec 0.5ppm RTL Dongle doesn't really seem to be living up to what I'd expected.  From a cold start it takes 15-30 minutes to (mostly) stop drifting.  But I suppose that's what you get with a TCXO (I don't really know).  I do know at cold start up it drifts in excess of 700 Khz, before it's really starts to settle down.

This is NOT the fault of the FTDX-5000 or the featured 100 Mhz upconverter I've built.  The upconverter after about 45 seconds basically doesn't drift.  It's pretty amazing and well worth the $74.00 I paid for it (for my needs, it's worth it anyway).


I've started to work on building my own HF upconverter that will use an OCXO that is stable to 200ppb (that's 200 parts per BILLION!), not something typical like the 25ppm, 5ppm's that are commonly available for a very reasonable cost.

(click to see larger)

The idea here is that I am primarily a CW operator.  My current Pan Adapter setup runs off the 9 Mhz IF output from my Yaesu FTDX-5000.  This then routes through a LNA, Bandpass Filter, and into an HF Upconverter where it comes out at 134 Mhz...this is where the RTL SDR Dongle operates via HDSDR.

I had a RTL SDR Dongle which was stable to about 60ppm, and the HF Upconverter was stable to about 25ppm for many years.  This meant that there was almost always some dicking around involved with keeping the Pan Adapter Software "HDSDR" lined up with the FTDX-5000's stable IF output.  Thing could drift at least for several hours slowly up the band until it warmed up and as long as the Temperatures in the room didn't vary too much things were 'close enough' to be useful.

NOW I have a 0.5ppm RTL SDR Dongle.  This thing is quite accurate, however my old HF Upconverter was still only accurate to 25ppm.  So I swapped out it's 125 Mhz LO with a TCXO that was stable to 5ppm (more or less, mostly LESS) the net result was that after about 2.5 hours the total drift was around 1.1Khz.  This is still REALLY CRAPPY for CW (Morse Code) which is very narrow bandwidth.

While Talking to recently we swapped emails back and forth for quite some time.  I found better TCXO's, and then came across the idea of using an OCXO.

The benefit of an OCXO is that they warm up VERY quickly compared to other LO's and once warmed up remain VERY stable.  Trouble is I could only find an OCXO that is in the 100 Mhz LO range which could get me to the 200ppB level at a reasonable price and delivery time.  So that's what I'm going with for this little mini project.  The downside to using a 100 Mhz LO is that the output of the 9 Mhz IF from the FTDX-5000 will be one 109 Mhz.  Pretty close to the FM Broadcast band.  In the past I've not had a lot of trouble with this sort of thing, mostly because I used a FM Broadcast Band STOP Filter in line with everything.  

So I can't really use the Band STOP Filter anymore.  However, this may not really be a problem.  The LNA4HF has a LO Pass filter, which should keep anything > 30 Mhz out of the primary input.  So that will help.  I'll keep all the coax lines very short (just a few inches) and use female-female type connectors to link all the components together.  I'll also keep everything shielded, and grounded as best I can.  I think this will work out ok.  

I'm planning to use an LNA4HF which includes a LOW-PASS filter in it already.  This then will route to a Mini-Circuits SBL-1+ Mixer.  Also I'll be using a 100 Mhz LO (200ppb) going into the SBL-1+ Mixer.  Output of that will route into the RTL SDR Dongle from Nooelec.

This "SHOULD" result in a MUCH more stable upconverted signal being fed into the RTL SDR Dongle.  That's the plan at this point anyway...this is sort of a side-project, but I wanted to share my thoughts on attempting to do this.

This is a review of a similar device and should help if you don't quite understand the problem I've been describing. 

I'll post more details on the various bit's and pieces I use and pix of the finished project when I'm done.

Also a Note: says they're working on something new that may resolve all of this within 10-12 weeks, and something else in the range of 3-6 months.  They wouldn't indicate what exactly they were talking about.  So that's why I'm moving forward with this little end-of-winter mini-project.

More details and where to get the various components I use as I get them.  Most of this I already know, but some may change.  So...stay tuned. (no pun intended! HAR!)

Here is a list of what I'm planning to use and where I got them:

Here is an example of how simple this really is:

VIDEO (Adam Alicajic)


While this is super simple to setup as seen in his video, I expect that I'll have some technical issues getting this to work as well as my "Ham It Up v1.2", at first.  But that's OK, because it should be way more stable than the Ham It Up since it's using an OCXO.  (I sure hope).

Anyway, this is going to be a learning experience for me.  I've never done this before, at least not like this.  I'll post mod's to this plan right here on this page as updates.  

One thing I'd like to do is in front of the LNA4HF would be to place a 9 Mhz Band Pass Filter that is 2.5 Mhz wide.  I don't really know how wide the 9Mhz IF is coming out of the FTDX-5000 but it seems to be at least THAT wide.  THE LNA4HF's LO Pass Filter should keep a lot of crap out of things to start with.  This idea is just to have more control of what gets in is all.

I MAY have to attenuate the OCXO output a bit, I've heard these things can be really strong, and if so I may have to use some in line attenators at least I may have to experiment around with that some.

I added some more filters after reading THIS and THIS to my design.

WARNING: my resulting design is meant to be modular enough to I can play around with OFF THE SHELF things as I wish.  This isn't a FROM SCRAP project and therefore it's a LOT more pricey than it would really need to be.  So be advised I'm already aware that I'm going at this from an expensive direction, and that there are cheaper ways to get/build filters etc.  This is intentional for what I'm attempting to do.  

NOTE ALSO: I'm aware that it's possible to get and use OTHER LO frequencies for this upconverter and that using a 100 Mhz LO can be problematic.  (so you don't have remind me :-)

Mixers I will test with:

The SBL-1+ from MiniCircuits looks like THIS.

The ZX05-1L+ from MiniCircuits looks like THIS.  (but costs 2/3 more @ around $37.00) It's advantages include already mounted SMA connectors all around.  Specs aren't the same as the SBL-1+ but they are similar enough that I may try one of these in the future. UPDATE I actually have ordered this, and one other similar.  I believe this mixer is +3db and the other one I ordered similarly configured is a +7db.

The ZP-10514-S+ from MiniCircuits looks like THIS. (and costs about 2x as much as the ZX05-1L-+)

100 Mhz LO 2x Frequency Multiplier Idea:

The ZX90-2-13+ from MiniCircuits looks like THIS. Depending on how strong the OCXO output really ends up being it may be possible to use this device (with it's 11db loss) to 2x the 100 Mhz output of the OCXO up to 200Mhz.  The Mixers above should handle that frequency range.   This would make the output in my setup from all of this to be at 209Mhz which would avoid the issue of the FM Broadcast band on the output to the RTL Dongle.  This item is simple SMA type connectors (plug and play) so would be easy to test and the price is reasonable around $35.00.  (I haven't ordered this, but keeping the idea in my mind).  The reason this might be useful is if the RTL Dongle needs to be placed far away from the upconverter, the output of the upconverter would be 100 Mhz higher than the FM Broadcast band....and EASILY filtered out with a band stop filter if needed.  I honestly don't think I'd need to go this route, but it's something to consider, for many reasons.  Lets say you wanted to use a different OCXO frequency because it was cheaper or something, this might help you get he output into a range that's more to your liking.  It has a fair amount of loss so the LO would really need to have some decent output (I think) but anyway...I just didn't wanna loose this detail in case I want to play with it later.

Everything for this has been ordered, and now I wait.  I'll post updates and pictures as things progress right on this post page.

(OCXO with Controllable Voltage Divider to Pin 1)
(subject to change, just a starting point concept)

After some reading I settled on using this OCXO it's a +2dbm 100 MHz 200ppb

I have several Mixers at this point.  I have an SBL-1+ which is a +7dbm mixer, a ZP-10514-S+ which is also a +7dbm mixer, and THIS ZX05-1L+ which is a +3dbm mixer.

After further reviewing the spec sheet for the OCXO I have it appears to me that the +3dbm mixer is probably the best choice of the bunch.  While I don't see a lot of difference in the Spectrum being displayed I suspect this +3dbm is better matched to the OCXO output. (I'm kind of guessing based on a very basic understand).

Saturday, February 14, 2015

OpenStreetMaps and OpenLayers vs Google Maps API

As noted in several previous blog posts here I wanted to try to get a OFFLINE mapping system working with the "Driveby System".  I believe now that I've found that mapping system in OpenStreetMaps using OpenLayers.

The reason it's nice to have a LIVE map while your driving with the "Driveby System" is mainly so that you can SEE how well the system has recorded the data while you're driving.  Being able to see the results of your live drive test is handy in knowing if you missed a street, or if you should drive a street more times to get a better, more dense results (perhaps you drove too fast the first time for example).  Driving too fast results in gaps in the map.  The idea with the system is to get as continuous/dense a heatmap result as possible. (e.g. without gaps, and WITH having smooth transitions from quiet to noisy areas).

The results are quit good!  The setup is NON-Trivial (meaning it takes following quiet a long setup of directions at least with Ubuntu 14.04).  I now feel the effort was worth the time spent (about 6 hours on my slow laptop) and about 4 hours experimenting with HTML and Javascript and my PHP code including the brief learning curve to read up on how to do a heatmap using OpenLayers.

I used the following URLs to get my system setup and running:

The results are almost as accurate as Google Maps API.  I say 'almost' because it appears at least in my area that OSM may have some outdated street detail.  For example, their map tiles show a street that continues past where it actually does.  Also some of the streets don't line up exactly where my GPS shows they actually are.  On my OSM heatmap using OpenLayers this shows my path that I drove slightly offset from the actual REAL street (according to my GPS, which seems to line up VERY well on Google Maps API).

These short comings are really kind of  'ok'.  I mean it's fairly obvious in the results where you actually where vs what was rendered in the Heatmap.  At certain zoom levels they look just fine.  However when you zoom in very tight, the path I drove with my GPS doesn't line up 100% with the road shown on the map.  

Lets not forget that we'll now have TWO mapping options!  OSM/OpenLayers while live drive testing, and Google Maps API later when you are back to a stable internet connection.   I don't plan on removing the Google Maps API work I've done from Driveby.  I'm simply adding more functionality to provide options.  OPTIONS In my humble opinion are ALWAYS a good thing :-)

I think the benefits outweigh any negative issues.  For example using OSM and OpenLayers means that no live internet connection is required.  Which is AWESOME, and was the primary goal of this exercise.  The map tiles are downloaded and stored locally on my laptop well before I go for a drive test and once installed remain there.  So there is no need at all to have any internet connection.  This is important for many reasons.  Cell Data access is expensive (for some folks).  Cell Data access is unreliable in some areas of the country especially when you are attempting to drive test an area that is remote which may end up being a common use area for a system like this.  Using a tethered Internet Connection (lets face it) can be a pain in the ass causing more frustration than ultimate usefulness!  Been there done that!

Another nice aspect of using OpenLayers is that it renders a much nicer looking heatmap than my experiences with Google Map API v3.

I plan on including config setup for use with OSM and OpenLayers in the Driveby System code which is now available on GIT HUB (minus the new OSM / OL stuff just yet, because I'm still working on it's inclusion into the Driveby Project.

Saturday, February 7, 2015

Driveby System - Work on open source mapping without need for live internet access

One of the biggest complaints I have about using my own "Driveby System" that maps the noise floor of various frequencies in order to locate sources of Power Line Noise is that currently it relies on Google Maps API.  This means that in order to view the maps from the collected data the system requires a live internet connection.  

This is fine in practice, because the data being collected is stored permanently on an attached SSD Drive.  Driveby has the ability to 'review' previous drive tests currently.  So when I return home and once again have an internet connection the mapping works just fine.

Also I have setup the networking to work both with a USB or Bluetooth connected internet connection via a smartphone or tablet capable of sharing it's internet connection.  However, in tests so far this has been problematic.  Loss of cellular internet connection seems to occur regularly (at least around here).  

This forces me to have to mentally remember all the streets I've drive tested in town.  And 52 my memory isn't as good as it used to be.  


I'm looking at trying to use a mapping system that allows the user to download locally the map-tiles that it requires.  Say within a 20 mile radius of the drive test area. (or more depending on the space available on the system).

I think that something like OpenStreetMap might be something I can use.  I've read that it's possible to save locally the map tiles.  

Another option is to use Google Earth (installed) and convert my map/noisefloor data to KML.

I'm still reviewing the best options at this point.  I like Google Earth, as I've done A LOT with KML in the past 10 years.  So that's fairly familiar.  There are also some nice features in GE that could be leveraged in the future.  However, because this is fairly bulky app to install and kind of hogs memory when it's running....I think it'd be a good idea to keep searching.

I've seen some really nice heatmap's done on OpenStreetMap but I've never used this system before so there's likely to be a learning curve there.  

Anyway, I just wanted to share some thoughts on what I'm thinking about doing AFTER the first release of the "Driveby System" code.


So looks like so far that I can't get OSM to install properly on either the TK1 or the Odroid XU3.  SO most likely OpenStreetMap is 'out' as a candidate. now to try to get Google Earth using KML to work.  Trouble is I think GE is semi-tied to having internet access too...blah!

Update 2015-02-13

Today I was able to get a OSM tile server up and running locally on my laptop using this.

Now I'm looking further into how to use OSM with this new mapping tile server. (again this is setup so that mapping would be possible WITHOUT an Internet connection.

The Tile server serves up maps on a web-server that would be running locally on my laptop and I hope to be able to provide coordinates to it to get back a zoomed in map to within a few miles of my location similar to how I'm doing with Google Maps API at currently.

Then the next phase is to work on adding a layer that would be like the 'heatmap' API in Google Maps.

SUCCESS!  Using OSM and OpenLayers I have a completely standalone 'tile server' that can map for me without Internet Access to the outside world.

This process requires A LOT of patience working through the URL noted in the 2015-02-13 Update above.  However, IT DOES WORK, and it actually works WONDERFULLY for so far.

I am now working on setting up HEATMAPS with the OpenLayers v3 API Once all of this is completed, I'll also update the recently released GIT HUB code for the Driveby System. (see other posts about that on this blog).

This is going to be awesome!  I can already feel like this will work really really well.  The API and the setup noted above all seem to work as directed and specified in their respective documentation.  (a rare thing in this world!)

Monday, February 2, 2015

Focus Areas - Suspect PLN

Now I have the Driveby System, and portable yagi's for 144, 432 Mhz, as well as Ultrasonic 40 Khz sound detection as well as the trusty AM Radio in my truck (which is amazing for finding noise sources sometimes).

With the new power supply 12vdc regulator installed in the "Driveby System" I suspect it will be WAY more sensitive than it was before.  I've made some more tweaks on it today (Jan 24th, 2015) in software and intend to test that out later today or tomorrow in the areas I've noted in the maps below.

Last nights discovery of a noisy defunct street lamp was actually very easy using nothing but the AM Radio in my truck, and 50.1 Mhz on a small whip antenna.  Once I located the area, I stopped and used the small yagi antennas panning around various power poles which took about 45 seconds to locate with those and the street lamp noise took about 20 seconds to find using the Ultrasonic MFJ-5008 (which seems to work VERY well, much to my surprise and joy!).

SO these are the areas I'll be working in this week.  Using a combination of all the tools I now have available.  Hopefully I'll narrow things down to the component level on poles that are problematic.  Ameren UE so far as ignored my email requests (maybe they're busy doing something else LOL who knows).  This just gives me more time to locate more problem areas to hand them when I finally do reach them.

This is turning out to be a way bigger problem than I initially suspected.  I had hoped it would just be a few things nearby.  In 2011 Ameren came and resolved (it seems) all the issues I had on the street where the tower is.  I've been hunting those old problem poles and so far not a peep out of them.

So it looks like I'm working the next tier out from the 2011 group of problems.

Results 2015-01-24

Tweaks appear to be doing really well now.  The new 12vdc regulator is SUPER low noise from today's experience.  I heard nothing from the trucks electronics (and obviously there's not AC inverter which was probably a stupid idea to start with...glad that's gone).  All I hear on the HT monitor while I'm driving is white-noise or power line noise now.  I really think that's making a huge difference.

I also adjusted the gain on the RTL's to '-g 10' from -g 0.  I also adjusted the bandwidth to 15Khz instead of 300 Khz.  These adjustments seem to have made quite a difference in accuracy.  Although I think '-g 0' would still be fine.  The antenna I'm using is a discone antenna that's good from 25 Mhz to 1300 Mhz.  And it seems to hear quite well on the bands I'm using with are all (but one 44 Mhz) in the ham bands.

I found at least 5-6 poles today and several of them had significant issues.  I also reconfirmed the poles behind the nearby middle school are indeed a source of strong noise - ON WINDY DAYS.

I've always noticed the noise is worse on windy days, which is probably a sign that most of these issues found today are simply loose components like insulators.  The ones I spotted with the Ultrasonic sound (40 Khz) using the MFJ-5008 today were all insulators.  This MFJ-5008 appears to work REALLY WELL!  After several ventures out with it now I've really found this INEXPENSIVE TOOL invaluable.  IT REALLY WORKS!  I shit you not.  Pretty good compared to the next up option that's over 2x the expense, and the next up from that is about 20x as expensive.  I've very happy with the MFJ-5008.

Also the portable ARROW ANTENNA's I bought are EXCELLENT.  Built strong, and reasonably priced for the most part. 

So...on with what I found today....(sorry for all the back fill).

It doesn't take much wind to make some of these poles really sing!

One thing you may notice is that all of these maps tend to agree with each other, I think this is a good sign.  The first map is "ALL" frequencies summed noise levels over their respective noise floors.  Each frequency has a slightly different noise floor but all are more or less with -0.5 dbm of each other.  

(ALL combined)

(44 mhz)

(50 Mhz)

(144 mhz)

(222 mhz)

(432 mhz)

"AM 1710" is fairly quiet in this area 1.710 Mhz.  Except that it's an excellent HEADS UP while I'm driving around to watch the line charts "Driveby System" generates as I drive.  Listening to 1.710 Mhz and 432.100 Mhz AM listening for Power line noise is VERY helpful I've found.  This gives a heads up that somethings coming, and a heads up when I'm right on top of it.  

I'm thinking about adding an HF upconverter and using one of the 3 spare RTLs with that to graph "AM 1710" as well.

(click to see larger)

Photos to follow from each of the above noted locations

POLE 571647 [near fire station]

POLE 571646 [near fire station]

POLE 572794 [rear of school near steps]
(VERIFIED with Ultrasonic, also pole guy is very loose)
POLE 572794 [rear of school near steps]
(Loose guy closest to camera POLE 572795 in rear also noisy)

UPDATE (AFTER 20150421) NOTE new insulators

POLE 570076 [rear of red city water building]
(TOP CENTER insulator confirmed via Ultrasonic)

UPDATE (AFTER - 20150421) NOTE new insulators

POLE 570076 (zoomed out)

POLE 570076 (LEFT TOP)

POLE 570168 (open arrestor)

POLE 570168 (open arrestor)