For anyone on the Amateur Repairs (*cough* yahoo *cough*) group or who follows me on G+, YouTube, or Twitter, you've likely seen posts related to my IC-706 mkIIG. I've pulled the radio out of service because of problems primarily on VHF-FM (at least it seems that's where the problems are at). In fact, since early December, I've been sporadic with transmitting with it, and I haven't transmitted with it at all since mid-January.
The problem I'm having is extreme static even with very strong signals. I've checked the likely (hopeful?) culprits of power cords and antenna connections. Since things seem to be fine on those - I've tried two power cords and three power sources and two different antenna setups - I've moved on to checking internals.
My second check was to poke around inside. I first looked at some of the audio waveforms at the NB test point and the WFM test point. Pretty interesting to see on a scope, and they didn't react to volume (that's a good thing, as this is likely before the audio amp!).
(PS in the video above: yes, I'm checking that with an oscilloscope probe. It works, even if it isn't necessarily 'right'... or maybe it is, I don't know).
My second test was to do something more ... practical. I know from some of the reading I've done in the ARRL Handbook, the owners and service manual for the rig, a video from Kenneth Finnegan (from The Life of Kenneth blog that I follow), and some comments from Mike M. on Google+ that maybe I should check the PLL board. And besides, checking stuff is easy, right?
The first check is the 60 MHz reference frequency. After finding and fixing a messed up power switch on my antenna analyzer and after checking it with the scope to ensure I wouldn't blow up my analyzer, I probed it and found exactly 60.000 MHz. Good.
The second test was of the PLL Loop Lock Voltage. Initially, I found that it was around 300 mV. This was too far outside of the required 2.0 V at 0.03 MHz. I thought for a moment that it might be a typo, although those things NEVER happen...
...and moved on to test the Main Loop Lock Voltage. It was far less than the spec 4.0 V on the first test (at 129.99999 MHz), so I didn't continue tests.
After some replies to the post on the Amateur Repairs group, I tried again to recalibrate the PLL circuit and was able to do it. This was, of course, after I removed a shield to test two transistors. I've reinstalled it in the truck and so far, so good. But we'll see. It could have been that the PLL was off causing weird errors that may have changed as voltages to the radio changed (it is mobile, after all), or it could be that something is still bad.
I risk falling behind in my weekly posts, so this is a post to provide a few small updates.
The Icom 706 is still screwed up on 2m FM. And maybe 70cm FM. I haven't tested SSB or AM on those, perhaps I will soon. I've thought up a way to test things, so soon I will have it on the bench (again) to test. I listened to a 40m SSB net all morning and noted no static that seemed out of place (e.g. static with an S9+40dB signal), so it still looks like things are affecting only the high VHF and UHF signal path. In a related note, I need to tune my 40m hamstick.
I am halfway through building a Bus Pirate. I ordered the remaining parts I need late last week and they are expected to arrive the same day I'm typing this blog post (Tuesday). I've really been chomping at the bit to finish this and play with it, and Ian (from Dangerous Prototypes) has uploaded several videos to YouTube that show how to use it, so I fully expect to watch several of them again.
In keeping with my want to build a small Arduino powered receiver, I purchased some parts for that (on the same order that arrives today).
I'm still working on my experiment that I talked about last week. There are some interesting findings so far.
I stopped by a Radio Shack while in the mall over the weekend. Apparently we're still waiting for their return to a not-useless store on the east side of Cincinnati. All I saw were the same things as the past few years, with the same high prices and same SMALL selection. Honestly, if Micro Center would open a mall on the east side of Cincinnati, it would be maker heaven. I do appreciate that the kids behind the counter didn't attempt to sell me a cell phone, but in their return to the 80s, they attempted to sell me batteries (and, like their cell phone sales strategy, they didn't take the first no for an answer).
On that, big shoutout to Micro Center - they've been growing their maker section with a decent selection of Arduinos, Raspberry Pis, Beaglebone Blacks, and even parts at very nice prices.
Before getting back into ham radio, I did something that I later found to be not optimal - I purchased a very nice 50" plasma TV. It sounds like everyone else's YouTube video of Plasma TV RFI, but if you want to see mine, the video is below.
I've looked into different solutions that remove noise based on a noise antenna, like the MFJ-1025 Noise Canceler. I believe these items work by inverting the phase of the noise and mixing it back with the signal to remove the noise. It is absolutely critical that these items have a great noise antenna in order to remove it.
The real issue I have is shown in the video above - the noise is picked up in the antenna. I believe that it is primarily picked up by the feed line because it is near (enough) to the front of the TV. See the diagram below:
So in order to use a noise canceling device, I'd need an antenna along my feed line.
I decided to try something else first - shielding my coax. I bought a pair of lengths of EMT conduit to run the coax in. This has a second advantage of being able to run coax really quickly. The only disadvantage is that I can't use ladder line in it. Given the situation, no big loss.
So right now, this is where I'm at. My HF feed line is crummy RG-58 that has an aluminum shield (insert angry face), so I haven't tested it yet because I don't have any crimp PL-259 connectors (nor do I have aluminum solder). Additionally, if this doesn't work like this, I will ground the conduit to see if that fixes it. If neither does, I'm sure that conduit would be an adequate noise antenna for a noise canceling device.
In other news...
I've been virtually off the air because of a problem with my IC-706. I posted something to Google+ and received a response that I need to look into, but I'm still looking for more clues as to why I'm getting major static on FM receive.
The filter sweeper is "stalled" because of work on other things. I will be getting back into it because I may want (or need) it for that crystal IF filter problem indicated in the G+ post mentioned above.
I'm not going to call it a spectrum analyzer anymore - the way I've designed this, it isn't going to do the same things as a spectrum analyzer.
The main difference is that a spectrum analyzer can operate without a signal generator, this won't because the signal generator is what is going to tell the Arduino what the frequency is.
I built another shield to stack onto the shield in last week's post.
There is currently no connection from the DDS to this yet, but that's one of the only few things left to do on the hardware side.
I also built a filter that will ultimately be the first filter to test. This is for my Softrock 20/30/40 and should pass 7 MHz while filtering 14 MHz.
This will fit in a Radio Shack small plastic enclosure - the plate was leftover from a small dummy load that I glued into the enclosure.
I've been reading a lot about receivers, and it sounds like one important thing is filtering. It makes sense too - simple receivers can suffer from front end overload due to a strong signal. And when on the ham bands, you never know where that strong signal may be - it could be someone driving down the road (which is a bit obvious once you see it), but in my neighborhood, if you don't know me, you're probably not going to know about the antennas in my attic.
I don't have a spectrum analyzer, and since I'm a traffic engineer, I really don't have access to one. I don't need a full-blown spectrum analyzer, either, I just need to sweep through the HF band and get the difference between signal input and output. Math will take care of the rest.
The way I figure it is this:
An Arduino (and this could become a Raspberry Pi or any number of other devices, but I'm going to use an Arduino because it's cheap and relatively durable) controls a direct digital synthesizer (DDS) module that just scans through it's limits... well, probably something like 0.5 MHz - 40 MHz - that gets me into the AM broadcast band (which can be a source of strong signals) to above the 10m band (I don't know what's up there, but whatever's there is probably not running 50,000 watts).
The output of the DDS would have an RF voltmeter and a probe to go to a filter. There would be another RF voltmeter to sense a filter output. The Arduino would handle not only control, of the DDS, but also sensing the voltage.
It'll look something like this:
The Arduino and DDS will look like this:
There will have to be a companion app to this. In Java (not just because I'm drinking coffee, but also because it's cross-platform). It'll look like this:
I have the perfect item to test with also. One thing I built and don't use (and never truly finished) was my Softrock RXTX. I need to build a filter for the output to keep the harmonic of the 7 Mhz fundamental from being too strong on the 20 meter band. I wound the coils while watching the Super Bowl-over-the-Broncos and printed a circuit board just before the game started.
I'm not really sure if this will work, but it certainly seems like it would, and I think it would be interesting to see how some filters respond on this compared to a real spectrum analyzer.
I have several "irons in the fire", but nothing big to post this week. However, I do have several things coming:
My third free PCB from Dangerous Prototypes has shipped and it is a Bus Pirate v3. I tried playing with the Bus Pirate Arduino Shield and Bus Pirate Demo Board. I've not had much luck and I haven't tried troubleshooting it yet. Associated with this, I've updated my Seeed Studio wish list
I printed a PCB for an upconverter that I haven't yet even attempted to build yet. Once I do, It'll make it here. Additionally, I just loaded a desktop with Debian, so expect I'll be talking about doing something with that as well.
It's membership dues time at the club, so I've been working on that. I built an Access database to help handle things, but now I need to sit down and actually do work. Have no fear, I won't post many details about that here :-).
I am getting ready to get into packet radio. I bought a KAM+ a year (or so) ago, and I want to get it up as an APRS IGate. Coverage around my place is pretty crummy, so I would like to improve that. Eventually, I'll probably replace the KAM+ with something else so I can play on packet (and I have some ideas).
I really want to build a QRP transciever. I've been looking at plans so I can find something. However, I may just buy a Rebel and add an e-ink shield to it. It looks like the Rebel Alliance (love the name, BTW) has paved the road to using an LCD screen. I want more and different, and certainly my code would be on GitHub.
I have been wanting to get back into getting frequencies from the Ten Tec Omni. I know this is do-able, but I need to purchase a connector and do more research.
I haven't forgotten about my logging project with the WF32, it's just been on hiatus because of life. I want to get back into that and get back onto HF mobile. I have a few additional thoughts that may be interesting to add.
I've also been blogging a lot more on my other blog. January is a busy in the transportation engineering and planning fields - the Transportation Research Board Annual Meeting is in early January. Just from that and intertwined conversations, I think that's set me up for 8 blog posts, and that's in addition to normal work that sometimes creates blog posts.
Edit: I forgot about one thing: I've been wanting to play on 70 cm a little, so I'll have some antenna builds to show.
Since my year will be full of a lot of traveling (a lot more than in prior years), and I still want to get into actually using CW, I decided it would be smart to have a quick reference of QRS nets to help me out.
I haven't verified that any of these exist, and I'm quite certain there's a few more out there. But here it is: . If I missed any, please let me know in the comments or via email at ke8p .--.-. ke8p .-.-.- us
I've had a sudden want and need to print a few PCBs. I'm not going to re-hash the toner transfer method that everyone else has documented, but I will note three things that I've learned:
- Sanding the PCB with 600 grit sandpaper and cleaning with denatured alcohol is a must (you could probably use acetone or isopropyl alcohol too, the idea is to get any oil or dirt off the copper
- HP Banner and Flyer paper works fine for this. That may be documented somewhere, but everything I see says to use a photocopier and manually feeding magazines through it. I'm using my own laser printer, so the idea of feeding magazine pages through it is a bad idea to me... now, if I was using a copier at the library or drugstore or gas station, I would have no reservations.
- This method is never perfect. Never.
- Drilling sucks. Design for SMT, if you can.
I'm working on several things, including a small guitar amplifier and an upconverter for my RTL-SDR. The upconverter is one where the PCB layout was supplied and I printed it. I put it on larger PCB than it called for, hence the crappy looking surround.
Prior to this, I did print two other PCBs. These were designs I did in Eagle. Both look like the PIC16 below (okay, the other, a real-time clock, was larger!). In both cases, these are just breakouts so I can use them with a breadboard. I forgot that I have a set of small drill bits somewhere.
Moving forward, I will be using both the software and techniques used by Contextual Electronics as noted on this page on kohanbash.com. The videos are EXTREMELY HELPFUL! I may still print prototypes at home, but with all reality, I may just print the layout on normal paper and set the parts on the paper to fit them and then send the PCB off to a service.
A side note on printing these things at home. Rocking trays full of dangerous chemicals for long periods of time is only fun when you're developing photos, and that ship has sailed (with my film camera, developing tanks, dark bag, and bulk film loader on the boat). If I do this a lot, I may end up building something that rocks the tray, as it would be pretty simple to build.
The problem came back. I tried switching out the power cable with the one I used in testing last time, and it was to no avail. At this point, I am going to do more testing to determine if this is an FM-only problem and/or if this is a VHF-only problem.
(1) Scratchy receive on 2M FM. Haven't tested other bands or modes. Scratchy-ness sometimes goes away in a sudden fashion (like flipping a switch). It's very much like a bad connection.
(2) Low audio volume
Potential Solutions from Research
Tighten chassis screws
"there is a known problem where the power connector is very close to a component (part of the 2m bandpass RX filter) mounted on the board. So close, that it can be knocked off the board when the power cable is plugged in or removed."
"Make sure the faceplate contacts are clean. Mine goes dead a couple times a year in my truck from this."
From AB8SH (local friend):
Check the power connection. The Molex connector used by Icom is frequently problematic.
From unnamed (and increasingly difficult to find) posts on the IC-706MKIIG Yahoo Group:
The power connector has been mentioned multiple times on the IC-706MKIIG Yahoo Group. Additionally, the ground clips have been commonly mentioned. Frequently, these are mentioned with the 17m oscillation problem.
First thing I checked was power and ground connections. The ground clips (that should connect to the case) weren't putting a lot of pressure on things. I bent all of them up towards the the case for good measure, although I'm not sure that fixed anything. I also ensured that all the internal screws on the PCBs were tight (all of them were).
The speaker looks aged (heck, you can see UV discoloration in the cone). Otherwise it looks fine.
After putting the rig back together, I put it on the radio bench connected to a DIFFERENT power cord and it seemed fine. A few days later, I mounted it in the truck. After driving a few miles and getting stopped at a long traffic signal, I decided to tilt the rig up more (yes, I had an appropriate Philips head screwdriver with me) and while being stopped at the light I quickly unbolted the front two mounting screws and tilted it up.
The radio died.
I (still quickly) finished bolting in the radio and while stopped at other traffic signals attempted to jiggle the power connector in the back to no avail. When I got to my destinations (another ham's house), I found that the plug came out. In subsequent testing, it seems everything is fine.
So What Was It?
I'm banking on a bad power connection. That being said, any mobile setup should probably include proper securing of power connectors and ensuring that road vibration won't cause things to come loose.
Edit: It is likely the power cord. I noticed static since posting this, so I'm going to replace the power cord and check the pins on the current one.
Happy New Year!
I'm no different than about 99% of all other bloggers out there that I have at least one post on at least one of my blogs devoted to New Years Resolutions. I decided to take a different approach this year. The main reason behind this is that there's a lot of other things going on, and a contest score or number of contacts is just a number - the larger goal is to have fun.
Last Year's Recap
The goals from last year were:
- Learn CW well enough to casually contest.
- Work a VHF contest this year
- Participate in more contests this year
- Operate more!
I've learned CW a little bit, and enough that I tried to make a QSO with a fellow SKCC member. I've been closer and closer, but I haven't had the time to do anything like QRS nets (which IMO would really help hone my receiving skills).
I didn't work a VHF contest this year, and I don't think I did more contests, although I did a few that are new to me - the CQ WPX and CQ DX. Both were fun, and that 10m opening to Europe during the CQ DX contest in October rocked. I really wanted to play on the 10m contest in December, but a poorly timed vehicle breakdown screwed that up.
Operating more wasn't as difficult as I made it. After a while of working two jobs, I had no time to get into the shack unless I was using my scanner to scan portions of textbooks for PowerPoint slides. During that time, I noticed that the "morning group" on the repeater was there, but there were several times I was driving home and nobody was out there, so I finally decided to put my IC-706 in my truck and started hitting DX on 10m during my afternoon drive (and also a few after doing morning traffic counts, which put me on the road to the office at 9:00 AM). It's amazing what a hamstick will do on 10. I haven't even tried 6 or 20 yet, and the 40m hamstick isn't tuned.
There are a few things that never made it to the goal list last year. One is that I started work on a mobile logging system, and the idea netted me a free ChipKit WF32 through Dangerous Prototypes. I fixed my Ten Tec Omni base station rig (which was nice when that second job was on hiatus for longer than expected). I presented about Arduino microcontrollers twice (to the Cincinnati FM Club and the Oh-Ky-In Amateur Radio Society).
I also learned a lot about electronics. A lot more than I would have expected. I never thought I'd be building with and using decade counters and DDS chips and the like.
I want to do some portable operating. That generally means CW (generally... easily). I have more trips for work this year than in years past, so having something better than an HT to go with me would be nice. That being said, I need to finish my CW education and obtain a portable rig.
I want to do more 'casual' contacts. By 'casual', I mean not-in-a-contest and not-in-a-net (which is fine, since I generally get on one net on 2m). I want to do more QSOs while on my way home from the office. This means two things:
- Finish the mobile logger.
- Figure out a better setup such that as soon as I'm on I-471, I'm either searching or calling CQ (maybe an expansion of the mobile logger?)
I want to play with more technology. Every year, something new comes out, like the Raspberry Pi, then the Beaglebone Black, and now the Arduino Yun. There's been new Arduinos, like the Due and the Leonardo. The Chipkit WF32 is awesome (wifi FTW!!!). The Ten Tec Rebel was released. The future there is exciting.
I want to integrate things together. I want to be able to easily log from my desktop, laptop, or my Nexus 7. Yes, I want LoTW support. No, I'm not going to begin writing it... yet.
I want to build more things. This past year was great - I built several small things. There's a few more things I have in mind that I want to get done and to the blog.
Speaking of the blog, last year I started (without a goal, mind you) doing posts on a weekly basis. I want to continue to do that this year. The other thing on the blog: new design. The design I have is a free design. It's okay, but I did start on a new one and I should finish it sometime soon.
That part above about 'a lot going on' is truth. The goal I can think of that isn't radio related is that I want to complete my first half-marathon (that's 13.1 miles) this year. That goal's pretty much low-hanging fruit since I've already registered for it and have been ahead of my training schedule. The extension of that is I'm considering running a full marathon by the end of 2015. I may hold off, but we'll see.
There's a few more non-radio things going on, but nothing too detailed...yet.
Well, I think that's it. I hope 2014 is a great one for all of us.