Dream tuner updates are posted regularly on the Alpha 4040 Yahoo Group - check in there for more frequent updates.  Here is a summary of the past month......

 

 

Well, it is that time of the month again!  Let me bring you up to speed on the Tuner progress.  First of all, we had a tuner on display at Visalia last weekend!  Lots of Oooh's and Ahhhh"s!  It appears that many folks are impressed with what they saw.  Unfortunately, we did not have sufficient power to run the booth, so we were in display mode only.  I think everyone will be impressed in Dayton this year with the new product!

 

We continue to make progress towards working out the bugs and improving the user friendliness of the tuner.  We have discovered a couple small hardware issues that we have to fix - the monitor scope function does not have enough communications bandwidth to properly indicate the modulation envelope.  We have identified the fix, and are in the process of implementing the solution.  Work on the tuning algorithm continues.  It is still not to our standards for performance, but is progressing.  Overall, the product is progressing nicely, albeit slower than we all would like.  I cannot wait to get mine!

 

Stay tuned for further developments!

 

-Joe Jurneke, 

Letter from Gordon Hardman, WØRUN  

A Magic Amplifier for a Magic Band!

Our lead-in picture shows a view from the 6m operating position at the recently concluded TX5K dxpedition to Clipperton Island. From such a remote spot, the propagation gods need to be kind if you are going to work them on anything other than moonbounce (EME). Lance, W7GJ is one of the most skilled 6m operators in the world, and managed to get 50 stations in the log. Of course, he had help from some of the best equipment available. If you worked him, chances are he was using the Alpha 8406 in the picture, but hats off to you as well- working Clipperton on 6m from anywhere is, to put it very mildly, not easy!

Most of the contacts were, in fact, made on EME using the JT65 digital mode. This mode is allowing more and more operators to rack up DXCC on 6m, regardless of the state of the sun. 6m is called the "Magic Band" because of the fascinating variety of propagation modes one finds there, leading to all kinds of surprises. This continues to this day- new openings occur at unexpected times, leading to new insights about the ionosphere. Being at the crossroads between HF and VHF means that all the propagation modes from both spectrum ranges are possible, and sometimes "mix and match". An example is shown below. It shows the paths of a winter opening between the southwestern US and VK/ZL. This has been interpreted as sporadic E at either end of the path, and F layer propagation in the middle.

In order to take advantage of all the available openings, it is necessary to have a cutting-edge station. Fortunately, it has never been easier to assemble a "dream" 6m station than it is today. A good place to start is Lance's web site. Not only is Lance a great operator, he has put together what is probably the most comprehensive web site for the 6m aficionado. You can locate it here: http://www.bigskyspaces.com/w7gj/. It contains a plethora of information, whether you are planning a station for your home QTH, a dxpedition, or a rover.

The steps in assembling a good station for the weakest signal modes are as follows:

1. Put up the biggest antenna you can
2. Run as much power as your license allows
3. Use low loss coax
4. Use a stable, modern radio with good transmit power stability
5. If you are running a digital mode, make sure everything is optimally set up
6. Become familiar with the web sites that report propagation

Starting with the antenna- the FCC may limit your power output, but there is no official limit to antenna size! Especially with EME, antenna gain matters. In making antenna trade-offs, the best place to start is Lance's web site. It contains a link: http://www.bigskyspaces.com/w7gj/6mTable.htm to VE7BQH's excellent table of 6m and 2m antenna characteristics. I love this table- you can do all sorts of trades here. If one of the 7 or 9 element monsters is too long, you can compare a pair or quad of smaller antennas- all the data is in the table. If you are going to do EME, then Lance highly recommends that you consider making the antenna capable of elevation adjustment.

As for the amplifier, running full legal-limit power output on 6m is now a snap with the Alpha 8406. It is designed  for the long key-down periods required by JT65 and other digital modes. It takes only around 50 watts of drive, and is extremely linear, so if you are going to be using SSB, you can rest assured that your signal will be clean. You can find all the pertinent information here: http://www.rfconcepts.com/PRODUCTS/New-Products/Alpha-8406-6-Meter-Linear-Amplifier.

Coax cable loss is really important for EME. While we seldom worry too much about this at HF, every tenth of a dB is important for weak signal VHF operation. At 6m, if you keep your coax cable loss to a minimum, it is generally of little advantage to put your preamp out at the antenna, as is done on higher VHF frequencies. Lance recommends you use LM600 or equivalent, unless the cable run to your antenna is very short. You can put your receive preamp between the 8406 and the radio, if you are going to use one.

Most modern radios are stable enough for all the weak signal modes, and there are many to choose from. It is important to make sure the power output remains stable and is adjustable to set the amplifier drive correctly.

In setting up for the digital modes, there are many things that must be adjusted, and getting them right can make all the difference. Fortunately, Lance has a checklist on his web site: http://www.bigskyspaces.com/w7gj/JT65.pdf. He also has additional training material and examples.

Finally, there are web sites which will help you spot openings and also coordinate EME and meteor scatter activity. These and other links can be found here: http://www.bigskyspaces.com/w7gj/links.htm.

I think people like attempting EME on 6m precisely because it is not easy. There is no room for sloppiness- the number of stations you can complete a QSO with goes up with every tenth of a db you can squeeze out of your station. You need the very best at every step- and we are there to help with the amplifier step!

73, Gordon, WØRUN