Month: December 2013

I added an element (orange) to my old dipole for the 40m band with a stub match (all other colors except black) so that I can also QRV on the 20m band.

Preliminary SWR measurement results that appear on my rig tell me that now I can QRV both on the 40m and the 20m bands if I switch on the built-in ATU.

So far so good? O.K., but the configuration is obviously wrong, which you might have noticed already. The new element (orange) should be directly attached to the end of the coax cable (black).

Another questions is that although this configuration (without a stub match) is often used for multiband dipoles with the reasoning that the element(s) not in resonance will only give negligible contribution to the total impedance when attached in parallel to other element(s), because they usually show a very high impedance, is it also true in case there is a stub match employed?

http://peanuts.wikia.com/wiki/Lucy’s_psychiatry_booth

I think I only have a very short Short-term Memory. When I am trying to decode CW signals, it is relatively easy for me to input each letter with a keyboard as soon as a letter finishes. Yes, I am good at touch typing.

With this mode of listening, you only need a single letter sized memory, which I do have. While typing letters, I have nothing in my mind because the letter-to-letter translation is so mechanical and, of course, I have no difficulty however long the word is. Understanding of the words and of the sentences comes from looking at the text I entered.

On the contrary, if I do not have a keyboard and try to do everything in my mind, it becomes exponentially more difficult to catch the word as its length increases. This is especially true when the word is unknown to me or is rarely used by myself.

Even if I luckily gather several words consecutively, it is another matter to grasp the meaning as a sentence, because the words once obtained in my mind will disappear very rapidly before establishing the structure and the meaning of the sentence.

It is said that from some experimental studies some manipulations (e.g., a distractor task, such as repeatedly subtracting a single-digit number from a larger number) impair memory for the 3 to 5 most recently learned words of a list which is presumed to be held in short-term memory.

http://en.wikipedia.org/wiki/Brown-Peterson_procedure
(No, I have not read the original papers yet.)

So in my case, the task of CW decoding is so distracting to me that the available short-term memory seems to be reduced to a minimum, preventing any further processing of the higher layers.

While talking with my CWmates on a mailing list, I was somehow persuaded to start using a bug key myself, a type of keys which I have never tried before.

There has been many discussions on the ML about bug keys, but each time I could not understand the point quite well, because I have no experience in the matter.

I ordered a Vibroplex Blue Racer Standard as my first bug, and I hope this will
help enhance my experience in the wonderful world of communicating by CW.

http://en.wikipedia.org/wiki/Chirality_(physics)

> Tried stub matching at 7MHz (d1=3490.4 mm, and d2=962.6mm) with unexpected results.

I found a mistake, which causes Z=a+jb to be Z=a-jb, because the sign of a delay between CH1 and CH2 signals is defined in a reverse way.

Please see my new page Antenna for the detail. In my Gnuplot Script on line 13, “cursor1” should have a negative value when the delay of CH2 against CH1 is positive. Perhaps the line was correct originally, and I somehow changed the sign later.

I do not have the ability to recognize the pitch of the tone, so I need some assistance to zero beat a station I wish to call. The pitch of the received signal is initially set to be 600Hz by a remote command to my rig, ICOM IC-7410.

If I set a different pitch, say either to 500Hz or to 700Hz, it seems that the bandwidth of the audio signal is shifted accordingly. (Listening to a white noise on the frequency nobody is transmitting.)

I have been thinking that I need some audio filters when I listen to CW signals, because the sound seemed to be too wide-band. I was almost building a circuit, and I finally noticed that my rig has a built-in audio filter. Better late than never, right?