28 May 2009

First Feldhell QSO

Looks like I need to move further very often. So from bpsk I tried feldhell. Nothing special about it, but I like its resilience to QSB. Moreover it leaves a lot to the brain for decoding, since it is a "visual" mode of communication. And apparently it works at 2.5W too!

The skip was about 7-800km that night, so SP9 right in the active area. The screenshot shows both my transmission (upper part) and how I received SP9. Note the discontinuities in his signal due to strong BPSK transmissions (visible in the waterfall on the RHS) and a local QRSS beacon.
Nevertheless his text was readable and the QSO could be completed. I should have tried with the narrow filter, and I need more practice in tuning hell signals.


27 May 2009

Shoud I buy an FT-817? QRP lifestyle

On an Italian HAM forum I replied to a person that owned an FT-817 for one week and then sold it, now considering to buy another one. I think it is worth copyng my words on my blog too. For non-Italian language readers, please use an online translator to get an idea of what I said.

Il QRP è uno stile di vita, è molta tecnica operativa e soprattutto molta pazienza.

Se il tuo obiettivo in radio è lavorare il DX senza troppa fatica, allora no, il QRP non va bene. Non è vero che le chiamate QRP hanno la priorità, al massimo il corrispondente si fa leggermente più paziente. Ma "ZYW QRP" non buca i pileup.

Se invece per te la licenza HAM è uno strumento per imparare, il QRP ci può stare. Ma lo puoi intraprendere anche solo riducendo al minimo la potenza del tuo RTX usuale, senza investire nell'817.

L'817 è un quadribanda comodo perchè facilmente trasportabile e consente di sperimentare antenne e attrezzature da campo, ma non allevia delle fatiche del QRP.

Io mi accontento di lavorare quelli che mi sentono (in HF) e di ottimizzare la stazione per migliorare la performance (contest VHF esclusivamente portatili a spalla). Così mi stupisco molto quando mi ricevono negli USA con 5W CW e l'antenna che fuoriesce dal balcone.

My opinion, of course.

23 May 2009

More on the netbook for shack use

One more thing I realized last night is that a SSD-based netbook is extremely quiet. It emits no hiss whatsoever, I doubt it has a cooling fan either. Disk capacity is limited to the size of the onboard card + any SD card you add (4-8-16-32 GB), but it poses no real problem if used for logging and digital modes terminal.

Just remember solid state disks (SSD) have a limited amount of read-write cycles, so backup often your data!

Does anyone know of RFI problems to SSD?

22 May 2009

Daytime view of my (30m) antenna

Since I believe digital mode operators are more online than usual CWers, I might receive more visits of QSO partners interested to see my "base loaded horizontal monopole sticking out of the balcony at 8th floor". After deep winter shots, here you are a Spring morning view:

The fishing pole points towards N-NE.

21 May 2009

Netbook (eeepc), FT817, digital modes

Our Summer holidays will take place on the same location of last year, just one week later. I already know the lodging, surroundings and somewhat, propagation too. Last year I did only CW QRP with a total of 56 contacts. The most limiting factor was operator's conditions, that became a lousy CW'er when tired. So this year I will (might) try digital modes.

I borrowed a netbook computer (eee PC, if you prefer) to check how it would perform. It is an Asus machine with 8.9" 1024x768 display On WinXP I installed Digipan, MultiPSK and WSPR as a starting point.

First test was with WSPR after syncing the clock (Dimension4). This netbook has enough computing power to keep up with the DSP/FFT analysis of WSPR slots (2 minutes). It takes 1'35" to digest two minutes of capture (one WSPR cycle), so the CPU runs at full steam 75% of time.

Then I tried to play with PSK31. I looked at MultiPSK because it supports several modes, but I was scared by the plethora of configuration options and the buttons density on the small 8.9" display. I tried a transmission test in my headphones but the signal was distorted. Discarded.

I moved on to DigiPan. I had used it in the past, so I am slightly familiar with its user interface. I love the multichannel reception capability. It sounds good without clicks or hum. CPU load is not excessive even with the multichannel scroll.

The keyboard of these netbooks is small. You need small fingers and a bit of practice to type fast without errors, so better plan good macros in advance.

This 6-cell battery (660mAh) lasts longer than I can afford to stay on the air, so the setup is probably valid for portable, exclusively battery powered, operations.

The same netbook also has Ubuntu 9.04 installed. I added HAM radio packages through the graphical interface and they load fine. Unfortunately fldigi transmitted signal sounds very bad and I could not understand how good the CPU usage is. I think I will stay with WinXP.

By the way, I used a fully isolated audio interface between the FT-817 and netbook. Since netbook has no serial/parallel port I kept my RTX in USB mode and used the VOX function. All signals picked on the FT-817 side Mic/Ear sockets.

18 May 2009

FT817 digimodes

We (family) are planning our Summer holiday. We will visit the same location of last year (IOTA EU-136, IOCA CI-096), with one more child onboard. Radio time might be even more limited than July 2008, and/or operator's energies further reduced.

A tired operator is a very lousy CW'er, so I am considering to try digimodes this year. SSB is out of question because it is too noisy and not effective at QRP levels.

I had once built a fully-isolated general-purpose soundcard interface. I also had prepared a cable to interface with FT-817 through the MIC/earphone plugs so that I could use VOX (VOX works only on the MIC plug, not on the rear DATA connector). But a strong hum was coming out together with PSK signal. After a lot of debugging and a bit of soldering I mentally re-counted the purpose of 8 wires in the FT-817 MIC cable: up, down, mic, gnd, ptt, fast, +V... what was the eighth? A brief look at the manual revealed a "mic gnd" line.

According to the schematic diagram, both "gnd" and "mic gnd" lines are grounded without further processing. But apparently they are not grounded right away near the plug.

Once I had connected both to my interface ground line the hum disappeared and I could complete two PSK31 QSOs. ALC down to zero, power to 5W.

Now I need more digimode practice and some macro review.

12 May 2009

Still no luck 6m mobile

It has been two weeks since I have started carrying my FT817 to work. The plan is to take advantage of ES openings while driving home>office and back, but so far I have had no luck: band closed.

I am active between 0600z > 0620z and 1520z > 1600z circa, usually calling /M around 50.155 MHz in JN35.

Funny episode this morning at a traffic light, when behind me stopped a car with a permanently installed CB antenna. My 6m antenna is a modified CB magmount whip. His plate on the windscreen evidenced he is a CB'er, but he horned lightly and cheered. I waved back and felt like a specie in risk of extinction.

All my sympathy to mobile radio enthusiasts, HAMs and CB'er.