Monthly Archives: March 2015

More portable QRP

Great weather this afternoon so setup the portable station. Lots of sunshine so the 60W panel topped off the batteries and had enough power to run the radio through the charge controller. The CQ WW SSB contest was running today so the 10m band was busy up to 28.7 MHz. I pointed the buddistick radial roughly northeast to try and favor Europe. I was receiving real well with many strong DX stations coming in. Final tally was 9 QSO’s with the farthest being in Australia…over 8000 miles on 5W! Works out to over 1600 miles/watt.

Well that was the good news. The bad news is that twice as many stations did not hear me. I think part of that is relagated to the nature of contests. I really can’t break a pile-up on 5W. Many contest operators are working so fast and don’t spend much time between CQ calls to listen. It helped to mark down the DX frequency and come back later when the pile up died down. 

CW Training Incentive

I bought a used straight key off of Ebay a couple of weeks ago to give me some added incentive to learn CW. It was pretty beat up when I received it but nothing was missing. I disassembled it, cleaned it and put it back together. The only issue with doing that is that there are 5 tiny ball bearings in each side support that kept coming out. I am not sure how I kept from losing one or more of them as is what usually happened when I attempt something like this.

I made the base from a piece of wood I bought at Michaels. They sell them as plaque bases. I stained it, then sprayed it with a couple of coats of clear enamel. I then mounted the key on the base with a couple of brass wood screws. The action on it feels pretty smooth now and it looks great in the shack. Seeing this idle on my desk everyday will hopefully give me the incentive I need to practice my code every day.

Photo Mar 15, 5 10 01 PM

HF Portable Antenna Choices

I am quickly settling on the Buddistick as my HF portable antenna option to cover 20m through 10m. The reasoning for this has come from analysis of different configurations using EZNEC. First let me just state this:

“You can’t change the laws of Physics”

Antenna design is a harsh reminder of this. In many ways I am glad I started this exploration by looking at the special case of portable HF antennas. The reason for this is that portability imposes some interesting constraints over antennas used in a fixed installation. The first major constraint is height. I set out with the idea that I may find myself in a location without a natural height source (i.e. trees) so that the antenna would need to provide its own support. Portable masts, painters poles camera tripods, PVC pipe…anything that can be compactly packed and then used as a mast. The higher you go the more you also have to deal with stability and that means guy wires. So far I have not dared beyond 8 feet for the feed point of the Buddistick, On 10m this gives me a vertical antenna height of about 20ft and a bit more when configured for 20m.

Doing some calculations on the Buddipole, which is essentially a horizontal dipole shows that for best results I need to get it up at least 16 ft on 10m and considerably higher for 20m. The gains of this configuration look promising and I intend to at least test this on 10m. The vertical may end up being the easiest to safely deploy in the field. A portable beam looks really interesting but the height constraint really kills its use in practice. a 2 element 10m beam is possible but getting this to work on 20m would be a challenge as 16 feet is about minimum.

So for now I am going to focus on the Buddistick configuration for portable HF. I will test the Buddipole on 10m and my ability to setup a 16-23 painters pole as a mast. If I can feel good about setting up the mast I may try the 10m beam but frankly not sure if it is worth the added expense of two long whips.

That still also leaves wire antennas which may be the best choice of all given that the portable mast up to 20 feet can work. I can use a dipole in inverted V configuration as only one support would be needed. Also have an end fed antenna to try in different configurations.

Well I think you see what I will be working on in the short term….

Some additional thoughts on yesterday’s QRP DX session

Did some calculations this afternoon to try and discover what went right during yesterday afternoon’s QRP session. The homebrew buddistick antenna is somewhat directional. The single radial points to the direction of highest gain. When I set up yesterday the direction of the radial was randomly picked and somewhat limited by where i could drive the stake that supports the radial 4 feet off the ground. I thought i was pointing generally in the Northeast direction but it turns out the opposite was true. I was roughly pointing at a bearing angle of 297°. The directivity of the antenna gives me pretty stable gain 90° on either side of that. So the swath of best coverage was between SSW and NNE. So here are the bearing angles of the DX contacts from my QTH:

  • Japan: 318°
  • Brazil: 128°
  • New Zealand: 230°
  • Argentina: 162°

The contacts from Brazil and New Zealand were will within the swath of main directivity. The South American contacts must have been just outside the 180° main coverage. Now what was interesting is that I was also picking up clear stations in South Korea and Australia (though I did not make contact with them). The South Korean station never heard my call at 5W. For grins I ran into the house to try and contact him on my main rig at 100W but I could not hear him on the FT-450D. Not the radios fault! Remember that my main antenna is a horizontal end fed antenna running north south about 20 feet off the ground. I simply do not have enough gain in that direction to pick up that station.

The other observation is that I was not picking up any contacts in Europe during that time as they would have been deep in the null created by the antenna.So when all is said and done the theory matches up with the practice! Looking forward to my next session with this rig and seeing what happens when i point it in different directions by moving the radial around.

Upgrades and Tweaks for the QRP Portable station

I made a few minor changes to the portable QRP station based on the Yaesu FT-817ND. First I upgraded the solar panel to a foldable 60W panel. It spreads out like a tarp on the ground or hangs over a chair. Added some power poles to this for quick and easy changes to the configuration. Also added a second wattmeter for the load side. Now I can monitor what is coming out of the solar panel and what is going to the load. Also swapped out the solar charge controller for a slightly fancier one. It was billed as a MPT controller but looks like it is a PWM controller with an LCD display. The display is nice as it shows what each component is doing.

I operated in overcast skies this afternoon for about 2 and a half hours and made seven contacts. The wattmeter from the solar panel showed .295Ah during that time while on the load side I consumed 1.057Ah. I am sure that on a sunny day the panel would have kept the battery fully topped off.

The Yaesu FT-817ND shows a current draw of 330mA on receive and 1.68A peak during transmit. So the go-box is pretty well set. Just need to get a cheap multi-tool to throw in there as you never know when something will need adjustment.

The big tweak today came with the homebrew Buddistick. I did some EZNEC modeling and found out some interesting things. The main two observations were that I needed to get the feed point higher to at least 8 feet (from the 5 and a half feet I tried last time) and replace the wire in the two foot PVC segment with Aluminum tubing. Both of these result in much better predicted gain and low angle radiation. So off I went to Lowes for a 3/4″ Aluminum tube. It was pretty straight forward to cut it to length with a hacksaw and drill two holes  at the same place in the PVC pipe where the wires came out of. The tube fits inside the existing piece of 3/4″ PVC pipe.A screw on each end holds the pipe in place and serves to connect the wires to the rest of the antenna.

Lastly I had to cut longer pieces of paracord for the guy wires. Straight forward enough, I simply divided a 50ft length into three equal pieces. Setup takes about 15 minutes in my backyard. The antenna tuned up easily using the Mini60 analyzer to about 1.4 SWR on 10m. So…put on my headphones and…the results?

First two contacts were in Idaho for the Idaho QSO party both were 59. Did a bit of tuning and picked up a CQ from New Zealand. He returned my call and I had a 33 signal report! Next was a 57 in Chile. Then picked up a lonely CQ from Japan who reported me at 53. This was followed by a 52 from Argentina and finally a 53 from Japan. The last contact was 7421 miles from my QTH. This worked out to 1484 miles per watt at 5w!

The changes I made seemed to work successfully and this on a day with SFI of 119, SN of 56 and poor predicted band conditions on 10m.

All in all a nice afternoon outdoors working DX on QRP!

Antenna Fever

OK so now I have antenna fever. As I had posted previously I have built and successfully tested a homebrew Buddistick. I have the parts for a homebrew Buddipole that I would like to try next, but now I am thinking more and more about a beam for 20-10m. A 2 element Yagi for 10m seems to be within reach with buddipole components. A reasonably sized 20m will require loading coils. I am working with EZNEC now and will post my progress on design in future posts.

First Contest – ARRL DX SSB Contest

I participated in the ARRL DX SSB contest this last weekend as I wanted to experience how these work. This contest is 48 hours long and is for SSB Phone contacts to North America. Most of the stations that I worked were on LoTW so it is a good way to make contacts for awards. Most of what I worked was on 10m and even though propagation was not the best, I managed to make several notable contacts:

  • Alaska
  • Saudi Arabia
  • Portugal on 5W (broke the 1000W per mile barrier!)

Starting to see the contacts show up on LoTW these past few days. If they all eventually post I will have doubled my country count in one weekend. It is great to see the bands come alive during these events but it makes me wonder where everyone is at the rest of the time…

Some additional Test Equipment

I have already talked a bit at length about the Mini60 Antenna Analyzer. I thought I’d mention a few other pieces of test equipment that I have collected over the years that may help with the Ham Radio Hobby. FIrst up is a basic DMM. Actually have about three that I have collected over the years. Nothing especially precise but they handle most jobs around the house and shack. I bought a USB Oscilloscope / spectrum analyzer about a year ago. It is a VT DSO-2810R 100Mhz dual channel scope. The unit is about the size of a smartphone and included two decent scope probes.Resolution is 8 bit at high sampling rates and 16 bit at lower rates. Overall it suits my needs perfectly as it is easily setup to my laptop when i need it. In the past few months I added a couple of micro-controller boards that have been configured as test equipment. These can be had at Ebay for decent prices but shipping times from China can be a bit long. One is a 0-30Mhz DDS based on the AD9850. It has a BNC output and a 1V p-p output. I am not sure what the output impedance is but seems to work ok unbuffered. I just received a similar device that is a decent L/C meter. I tested the homebrew buddistick coils and found them to read much better than on the Mini60 with a lot less hassle. Also tested some known caps and coils and found the readings matched that parts quite well.