Sunday, December 30, 2007
La partie 3 est désormais disponible ici
Je suis en train de rédiger une partie 4, qui traitera d'antennes de réception optimisées pour la CDR. Si vous avez des idées et/ou des suggestions que vous êtes près à partager, n'hésitez pas soit à poster sur ce blog (avec un lien vers votre page ou une autre page intéressante), soit à me les envoyer par email. Bonne année 2008 à tous...
Wednesday, December 26, 2007
Monday, December 03, 2007
CN8PA, W7EJ, W7ZR in CN2R station, last march after the WPX-SSB
A selection of AS and OC QSO's. Here also a few ones are very close from EME qso's (when they were done random on CW !). You may note the difference between the NNE beverage and the ENE one on the QSO with VK6HD (i switched to the right beverage only at the end of the QSO, when Mike was sending his zone). There is only 30 to 35 degrees AZ between the 2, but it makes quite a difference !
Thursday, November 29, 2007
This audiogram, shows one of the problem I experienced and slowed me down a bit: The 600ms delay between the last transmitted dash and the return of the RX, is defenitely too long, and generated quite a few "prefixes" misses (as you can hear in the following recording). As a security, I just used Joseph's sequencer (which protects the RX and the beverage preamp) on the "PA-PTT" output of the MK2R... I should have looked at this more carefully before the contest !
10mn of the second hour, with a good rate (>200). As mentionned above, quite a few prefixe repetition requests could have been avoided by optimizing the RX return time... my mistake !
Beyond the QRM made by my compatriots, starting a +170Hz from my freq, the benefit of the diversity receive is illustrated on the QSO's with W1TO and EA4AYD (only the "beverages receiver" is recorded here). Nothing was audible from W1TO before I switched to the NW beverage, but I heard him calling on the delta in my left hear... the same for EA4AYD, who was too QRM on the beverage, but perfectly audible on the transmit antenna.
Category: SOSB80 HP
Total: VQ:2382 ZN:33 CTY:115 Total Score = 638,324
With Gisele in Saint-Malo one week before the contest. Who said it is always raining in britanny !
The story starts with a SSB-QSO with joseph on 160m. I had already planned a week holiday with my wife in Britanny, when Joseph offered me the chance to use his station for the contest. The 20m antennas being down I had the choice between SOSB40, 80 and 160... Don't ask me why I said 80, but this was my choice ! (maybe because I knew that Joseph had made a big score during the SSB-leg, so this was a guarantee that the station was working fine on this band !). Anyway, when you have a host like Joseph, you don't have to worry... I phoned him during the week and he had already retuned the TX-antenna in the middle of the 80m CW-band. On my side I had tested a "diversity receive" concept that I had in mind for a few months and everything was ready, so it did take less than one hour on friday afternoon to be ready with my Icom transceivers, the MK2R+ and my usual laptop and software !
Wednesday, November 14, 2007
Wednesday, October 10, 2007
Monday, October 08, 2007
Wednesday, October 03, 2007
Wednesday, September 26, 2007
Wednesday, March 28, 2007
Saturday, February 24, 2007
The bandwith was the main concern, but as shown by the graphs most of CW-contest band is usable with SWR below 2. Although I have full confidence in computer simulation, the results obtained with this aerial during the ARRL-DX really surprised me. see http://lists.contesting.com/archives//html/3830/2007-02/msg01551.html ). I believe that on top o f the 3.5dBd gain its main quality has been to protect us from the heavy EU-QRM.
View of the aerials installed at CN2WW, the fiber mast supports the 40m dipole and the 80m director while the tower supports the 40m reflector and the 80m dipole.
As information the dimensions provided by the computer model are the following one: For 8m spacing and a center angle of 120 degrees, the half-dipole is 21.18m and the half-director 20.6m. But of course the dimension may vary, fonction of the height, the angle, the environment, the wire used (i.e. plastic coated wire has a velocity factor in the order of 0.95), so it is strongly recommended to adjust the dipole alone first below the desired frequency (removing the director on the computer model gives 3.465 for jX=0) Then place the director and cut it until the desired frequency is obtained (3.532 for jX=0 ). I think that it is the best way to get the aerial working as expected.
Computer models (MMANA or NEC2) can be provided on request.
Sunday, February 04, 2007
Tuesday, January 30, 2007
The good the bad and the ugly !
Recently bought this TRX for travelling around for contests and to replace my 706 which did not have the adequate CW/RTTY filtering for contesting...
Weight= 2.3kgs, was also one of my motivations, taking into account the new limitations for hand-carried cabine luggage!
Tried this weekend in CQWW-160 and REF-test
- Being familiar with the 706, it did not take long to get familiar with it... a few things have changed, but the user interface philosphy, remains moreless the same.
The display is really bright and contrasted and does not require that I put my glasses on...
For a CW-contester RX DSP-Filtering is really the strong point of this transceiver, together with the usual ICOM strong points (I am also owner of 756pro2). The "strong signal" resistance is not as good as my pro2, but sure better than the 706 (ie on 706 the preamp was unusable on 20m and the attenuator often required on 40)
A few have reported temperature problems... did not see this even during long sterile auto-CQ sequences with 3s RX-time. The temp indicator always remained in the blue zone (Had even tried 4 hours of the same regime at full CW-power on a dummy load B4 the contest - no problem...). Haven't tried yet in TTY... will see!
- Do not like the RIT/XIT on the coaxial pot... even more unusable than the 706 RIT (why not the main dial when selecting RIT like in the Yaesu FT857D. It Would be far more convenient !). Of course it is possible to use the split, but there is always a risk to move the TX freq, especialy when using auto-CQ from your contest software.
- A pity that the local-monitoring (CW-sidetone and SSB-monitor) is not available from the fixed-level audio output on the ACC connector (if you record your pile-up through this line, you won't have your own signal !)
- The RF-power output is a bit "limited": From 95W on 160 down to 80W on 10m and 75W on 6m (but will check this again with a professional wattmeter). Not a problem when using a modern tetrode PA or an SSPA, but a bit just for entering LP-category (especialy in those contests for which LP is 150w
- The long spotted "audio white noise" is really annoying with a normal headphone without pots. It becomes acceptable with audio-pot around 11h, so will make an external attenuator / low-pass filter for the next contest, but it is a pity that Icom did not fix this pbm, despite all user-complaints (maybe for the PRO version!?). Maybe another solution is to use a vintage low sensitivty/limited bandwidth headphone.
SUGGESTIONS FOR THE PRO VERSION
- Improvement of the a/m BAD and UGLY features
- Why not make the second SO-239 connector (dedicated to VHF/UHF) usable for a second HF antenna and/or a RX antenna (it sure would be appreciated by 160m freaks !). It could be done from the main setup menu (disabling VHF/UHF, if required)
Of course this is a CW-contester/DXpeditionner point of view which may not be relevant if your main use is as mobile-rig... Despite the few a/m problems it is definitely a good choice for a small TRX, so I give it 4/5.
Regards and 73's
Tuesday, January 09, 2007
Monday, January 08, 2007
Class: Single Op LP
Operating Time (hrs): 8
Total: QSOs = 112
Total Score = 1,416
inverted-L on 2x 12m fiber masts
One of the 12m mast used to support the 160m inverted-L
Part-time effort, just to enjoy the low-noise level of my secondary QRA on a band which is usualy forbidden for me due to the HT-line hi-noise level at my main location. Quite a few DX stations heard, but none logged...
Une participation en diletante, juste pour apprécier le calme radio-electrique du QRA secondaire, sur une bande qui m'est habituelement "interdite" en raison,du fort bruit de fond généré par la ligne 380kV qui jouxte le QRA principal. Pas mal de stations DX entendues, mais aucune contactée...Les condx ne semblaient pas terribles, aucune station W/VE dans le log, alorsque j'en ai assez facilement contacté qqs unes pendant la semaine...Stn: IC756 et antenne L-inverse sur 2 mats en fibre de 12m. (pas de radians...juste le grillage entourant le QRA en guise de contrepoids...)QTH: Arzon, dpt-56 (au bout de la presqu'ile de Rhuys, entre golfe et ocean...)
Above, the mast, also supporting a 30m dipole, and here the R7 antenna