Since I had a few minutes after the XYL went to bad (after a *very* busy Saturday for both of us), I went into the basement and played with the antenna analyzer.

This isn’t the most ground-breaking post on my blog, but they don’t really teach much about antenna analysis in traffic engineering classes!

Scop’d

The first thing I did was drop the frequency of the analyzer to something low and see how much power the analyzer puts out.  4V peak-peak.

SWR Check – 25 Ohms

SWR is based on the mismatch between the impedance of the source and the load.  So a 2:1 SWR could mean that the load is twice or half the source impedance.  So I decided to put a few resistor arrangements on the analyzer and see if what happens is what I thought would happen.

So I had these terminators from way back when they used BNC token ring networks. I’ve never worked with anything but Ethernet (using RJ-45 connectors), so I’m not sure how I got these, but they came in handy for this.

This one is 50.3 ohms. Within a 1% tolerance.

This other one is 49.4 ohms. Just around 1% off. For what I’m doing, close enough.

This was my redneck arrangement. This basically put the two 50 ohm terminator resistors in parallel.

This doesn’t quite have the resistance I was expecting, but the SWR is correct. Of course, there’s all sorts of stuff going on with the open end, the many connectors, and the 4 foot piece of RG-58.  Given the fact that I had two 50 ohm resistors in parallel, I think I should be seeing 25 ohms R and (ideally) 0 ohms X.

This seems a little more like it. Still a nearly 2:1 SWR and close to 25 ohms R, with very little reactive ohms.

SWR Check – 100 Ohms

Since I couldn’t figure out a way to make my two BNC terminators in series, I pulled a resistor out of my parts bin.  It was really a 98.3 ohm resistor, according to my non-lab-grade Radio Shack meter, so I figure that’s close enough!

Close enough to 100 ohms.

This is how I did it.

Hey look, exactly as expected. 100 ohms resistive, and 0 ohms reactive.

Other Dummy Load Test

I had a dummy load I built for QRP uses (specifically the Softrock).  I built it a while back, which is why the callsign is wrong.

Just pretend it says “KE8P Dummy Load”

70 and 4? SEVENTY AND FOUR? WTF, it should be 50 and 0!!! I’ll just blame the extra resistance and all the reactance on the cable…

Maybe this is why it isn’t perfect. My coax isn’t exactly Belden or Times.

Capacitance Checks

So the MFJ-259B has a capacitance check on it.  This is really for the capacitance of an antenna, not for what I did in the pictures below.  I basically took a ceramic disk capacitor and clipped one end to the ground and the other I held into the center conductor of the antenna port. This is a 10,000 pF capacitor.

On 80m, this capacitor has 6,298 pf.

Up at 91 MHz, there’s only 8 pF of capacitance.

I figured the stuff above was a little more fun than me talking about how I tested every antenna I own… again.

-73-

Oh crap, that probably sounds bad.  Ah well.

So my first find was a key.  It’s nice, heavy, and probably has a history, which I added “purchased for $35 by KE8P” to.

I found this.  For $165.  Like any normal ham that likes to push buttons and turn knobs, I turned it on, just to be greeted with it flashing “LOW VOLTAGE 6.5V”.  I figured that was a sign that it probably works.

And when I got it home, I found these in it.  Ten Energizer rechargeable batteries.

So I removed the batteries and plugged in a wall wart.  I was greeted with “VOLTAGE OK 15V” and something like the display in the picture above.  I did check my dummy load, it claims it is around 50 ohms at 1-1.3 SWR.  Guess it works!

Also included were these.  They are coils to use the analyzer as a dip meter.  I didn’t really need these, as I built one (they’re really quite simple).  My built version worked quite well for the coax traps on my attic trap dipole.

So I did try it with my HF and 2m antennas…

Not bad for the severe destruction of 5 clothes hangars

My HF antenna isn’t too bad on 2m…

…and it does okay on 20 meters, too…

The third purchase was a case for my SoftRock

The last thing I got was some fiberglass mast.  I didn’t take a picture of that.

I didn’t take as many pics as last year, but I did take some…

The view walking in on Friday morning.

A Commodore 64. The seller claims it still works. $10.

The straight key I bought

A tube tester.

This is an odd find at a hamfest. This is a traffic signal controller.

This was one of three similar go boxes made out of the same tackle box, most out of similar radios and tuners as well.

The antenna analyzer I bought.

VERY clean Hammarlund

Very clean Imperial

AM transmitter in restoration (front)

AM transmitter in restoration (rear upper)

AM transmitter in restoration (rear lower)

This year is different from any of the past two years I’ve gone to Dayton. The first year I went to Dayton, I wanted a simple HF rig and knew my budget only supported something like a Radio Shack HTX-100. I bought two for $45. I also bought a power supply for it (an Astron RS-12).

Last year, I was looking for an LDG tuner for my IC-706. Found one for $85. I’m not even sure I bought anything else.

This year, my tastes are hopefully smaller.

• A nice straight key… for a damn good price
• The ARRL CW book that just came out… if it is a damn good price
• Some air variable caps… I could use some smaller ones as well as some matching pairs for matching antennas
• Maybe some tubes (for both a linear and potentially for a guitar amp for my brother-in-law)
• Probably some other parts

Dayton’s Friday through Sunday, and this blog post wouldn’t be complete without a list of what will be in my bag.

• An umbrella (maybe my raincoat)
• A small notepad and pen
• A small bag of snacks (last year, it was goldfish crackers)
• My HT and headset
• A backup battery for my phone
• A bottle of water (disposable)
• A towel (small)

Things I know I will buy:

• A beer

Things I know I will get:

• Another Dayton Pin
• A Yaesu hat (if they have them)

Things to keep in the Truck

• A bath towel… rain is expected!
• A small cooler with ice and a few bottles of water

Other Stuff

Last year, there was a guy from Linux in the Hamshack. If he’s there again, I may give them a donation since they did direct some traffic to my website (and that was totally unsolicited). I listen to their show far too seldom, and it is an interesting show.

Last year, I tried to make it a point to make it to some of the forums. This year I might, but probably not as much – I tried to attend the microcontrollers forum last year, there were no seats available in the oven… er, room… when I got there.

I have been accumulating projects on my workbench, and it is getting near time to jump into them. I thought I’d do a quick blog post discussing my immediate plans.

Antenna Analyzer

I bought a pair of direct-digital synthesizers a month or two ago, and the first thing I want to do is build an antenna analyzer, which is something I desparately need. In fact, it would be good for some of my next projects.

Balanced Line Antenna Tuner

I ran a new antenna in my attic, and wanted to be different, so I ran ladder line to it. My tuner with my IC-706 is an LDG IT-100. It is a great tuner, but it is really meant for unbalanced coax. I want a real balanced line tuner. In the meantime (and as I write this), I’m going to build a balun for it.

QRP Transmitter

Since I have two direct-digital synthesizers, I figured the other can be a part of a QRP transmitter. CW only.

APRS I-gate/Digipeater

My area is pretty bad with regards to APRS. I’m going to fix that.

Frequency Counter

The last thing I want to build is a frequency counter. This will likely be my first project with a PIC microcontroller. It won’t make it up past 150MHz, but I am going to try to hit 150 MHz.

I bought a new-to-me radio. It is a used FT-7800R dual-band (2m/70cm) mobile. The price was right: $195 before taxes. Once I got it, I high-tailed it home and opened the box and….

POW.

It hit me. The stink of cigarette smoke.  Not enough to knock me over, but enough to potentially stink me out.

So I asked Twitter, Facebook, and a few locals how to get the smell out.  Their answers (all good ones) are in the Storify story below.

So I did with what I could with what I had.  The images below tell the story.

I took the rig apart and put it in a box.

I sprinkled lots of baking soda all over the parts. I left it like this overnight.

I attached a fan to the side of the box.

I let the fan run for a while, maybe 12 hours. Yes, I ran it with an expensive linear power supply!

After running it (with this as a small exhaust), I did a smell test over this, and viola! No noticeable smell.

So the exciting conclusion is that this was mounted in my truck on Saturday night, and I got into the truck on Sunday night to actually test the radio (after having it mounted for nearly 24 hours in an enclosed truck in my garage).  I detected no smell of smoke in my truck.  While nobody was on the local repeater to assist in my test, I had handed one of my HTs to my wife and she gave me a thumbs-up indicating that indeed, the sound was good.  Also, I’ve had good sound reports on the morning drive, too.

At any rate, this is one of those “your mileage may vary” situations.  I may be right, or I may be lucky.  But I’m not smelling smoke!

-73-

Those on Twitter already know that I’ve been tasked with managing the club email list because I am the secretary of the Milford Amateur Radio Club.  I asked on Twitter if anyone had any hints and I mostly got sympathy.

So I looked for something, and stumbled upon CiviCRM that looks like it may help.  CiviCRM is an open-source Customer Relations Management system that looks pretty cool.

The problem is, it requires MySQL 5.1.  That’s not a problem FOR THEM.  It’s a problem FOR ME.  I use GoDaddy shared hosting, and they have resisted every MySQL upgrade since 5.0.  So I looked at GoDaddy’s forum, and found a cornucopia of people demanding it, all met with the same response of “we have no plans to upgrade that on the shared hosting plans, but buy a Virtual Private Server (VPS) or Dedicated Server.  Now, I pay about $100 per year for “Ultimate Shared Hosting”.  A dedicated server is $100 PER MONTH.  A VPS is $30 (ish) per month.

Mind you, the shared hosting works perfectly for me, as it’s cheap (I make no money from my websites, neither directly nor indirectly.  I don’t have the money to go to a dedicated server, nor do I have the money to go with a VPS, and if I did, I wouldn’t because I don’t want the added workload of administering a server.  I used to do that, and I got away from it because I wanted to spend time on content rather than computer administration duties.

So here I sit.  Via Twitter, I’ve received recommendations for BlueHost, DreamHost, Linode, and WestHost (and had a nice twitter conversation with an account manager from WestHost).  I haven’t made up my mind, and my hosting contract with GoDaddy is up in June.  I’ve enjoyed great up-time and service from GoDaddy in the past, but running several versions behind on the backend database is not only an annoyance (for not being able to use CiviCRM), but it is absolutely frightening to think that I may have other peoples’ emails in a database on a server that isn’t being kept up-to-date with security patches.

GoDaddy, you have a week to meet my requirements.  Upgrade to the latest MySQL.  Else, Daddy, you’ll Go.  Moving is a pain, but I will do what I have to do.  And that is NOT a promise.  I may decide to leave anyway because of how long this has been going on.

-73-

After reading a few blog posts out there from others, I decided that it would be interesting for me to get hold of an AD9851 module.  My initial plan is to build an antenna analyzer and something else (I bought two).

The major engine of these modules is an AD9850 Direct Digital Synthesizer.  This chip can be purchased in quantity for $15.25 EACH from Newark.  From Digi-key, $15.37.

The two modules I purchased on eBay were $8.90.  Total.  With shipping.

And these modules aren’t just the chip…

So I don’t totally understand how this eBay seller makes money, but it appears he does (it appears he’s/she’s sold quite a few of them, based on their eBay feedback rating).  What I do (now) understand is why we no longer do electronics manufacturing in the USA.

After ordering this (at the time of writing, I’m still waiting on shipping), I started looking in to adding Ethernet capabilities to one of my Arduinos.  So I looked in to the ENC28J60-based chipsets.  After finding one for £22.90 and one for $35 on Sparkfun, I looked on eBay.  $4.09 each from Hong Kong.  $2 for shipping.  At least this isn’t as egregious as the AD9850 modules, as the ENC28J60 chip is $2.36 in quantity from Digi-Key.

I can’t imagine this is news to anyone in the electronics industry, but I’m just an amateur radio operator and traffic engineer.  I found this interesting.  And I’m not complaining, as long as this stuff I get from China works!

Of course, there is a drawback to this – the wait.  I got a confirmation of shipment for the DDS modules on March 26, 2013, and they arrived on April 6, 2013.  I ordered the Ethernet modules on April 5, 2013, and they have yet to arrive.  So there is a delay, but with some planning, a hobbyist like me can deal with it.

-73-

On March 30, I went into my attic to install a few antennas.  I learned a few things that bear passing on.  Some of these are in pictures, some are text.  These are in no particular order.  These assume you have cellulose insulation (the type that’s blown in).

• Be ready for a dusty environment.  If you don’t wear a dust mask, be prepared to blow black snot out of your nose
• If you wear glasses, make sure they are in no danger of falling off (I almost lost mine, that would have been bad news to drop them into the insulation)
• Make sure you have extra batteries for cordless tools
• Make sure coax is supported at the top.  A 20 foot run of coax can be heavy, and you don’t want the line stressed
• Make sure you have a flashlight (as well as an area lamp, like a clip-lamp)
• Take a plastic rake up there with you.  Use it to move the insulation around.

A piece of mason’s line (in stylish hot pink) is great to mark where the hole is for coax.

Look for things like a catwalk (like my attic has), just make sure you’re walking on wood and not PVC!  Also, don’t expect the catwalk to be on both sides (in mine, it is not).

-73-

After installing my first HF attic dipole and noticing that I can hit Alaska and the Carribean really well and can’t hear New England at all, I decided I want another that is perpendicular to it (then maybe I’ll hit New England and Arizona… and Hawaii!).

I decided to do this antenna a little differently.  Consider it an experiment.  While I went to a lot of great lengths to put traps in my prior antenna (which shortened it’s length considerably), I decided on this one I want to try window line and see if the interference problem caused by my plasma TV is different.  If not, I may be off of 40 and lower until I replace the TV with an LED TV.

Since the window line will be going down along a ventilation shaft that’s pretty large, the one concern I have is that I can’t put metal conduit in the shaft (one thing I wanted to try was to put a grounded metal conduit in the ventilation shaft and see if that fixes the interference problem).

So anyway, the pictures are below.

This is the stress reliever in the center insulator. I drilled three holes in a 3/4″ PVC coupler and used two wire ties to ensure that there isn’t too much stress on the wire joints.

This is the insulator in the center of the dipole. The long wires were soldered to the twin-lead. The PVC coupler allows for me to hang it via mason’s line.

The two sides of the dipole – wires at ~33′ each – are coiled around CLOSED coffee cans, and the window line is coiled. Everything is taped with masking tape so it can be removed easily. The cans have to be closed due the insulation in the attic – open cans would get insulation in them, closed cans do not.

This was the only picture of the installation I could get. Let’s face it, it’s a wire in an attic, it isn’t going to be easy to see nor show anything interesting. Hope that metal plate doesn’t create a problem (there’s one on the other side too, so at least the metal plates will balance out).