High TX-power and high transmit-cycle should be used with care !

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f6irf's picture
Last seen: 12 years 7 months ago
Joined: 2008/04/18 - 12:24
High TX-power and high transmit-cycle should be used with care !

First of all, I am not a QRPP integrist and I do not see any problem using high power when it is necessary, for example on low bands (80/160),or on an "apparently dead band", assuming it is done in a clever manner. This is also quite normal for stations located in very remote areas.

Like in many other ham activities it is a matter of mutual respect...

IMHO What is not acceptable, is for stations in high density areas (EU/NA) to use high-power together with high TX-rate together with a "cloud burner" type of antenna (a low dipole - a dipole even at 20m is still a "cloud burner" on 80m). This type of practice has for consequences a signal over S9 for stations co-located in a 1000kms circle, thus blocking RX-AGC of receivers and making impossible to copy weak signals.

I understand that be heard by stations over 10,000kms maybe exciting on low bands, especialy if you use a low horizontal antenna, but WSPR is not a DX pile-up so no need to use the same unfair practices (*) to get through... (and you won't get a QSL for your DXCC anyway !)

So if you want to test a particular DX path, you may increase your power, but for a single period or 2 per hour - not more- preferably using "manual control" in the period just after the DX station transmitted. First you won't annoy the others who are trying to decode this station (in the same period) and you will leave a few time slots for stations using lower power... This is especialy critical, when the "short distance" propagation is at its maximum...

But please do not leave your station for hours at 33% TX-rate, using 20W or more on 80m seing the other continental stations reporting SNR's >10dB (of course if you have an indoor mag-loop 20 W is still OK !). Obviously the same apply to all bands, where short distance pathes are likely to create big signals (IE 40 30 and 20 during daytime)

In short please use your brain: adapt your power settings and TX-rate to the band condx, the perf of your antenna and when you got spotted once by the DX, please QRP! (the real challenge is to get heard with as low power as possible TX-power)

Just think twice before using high power and high TX-rate...


(*) I.E. spend more time transmitting, than listening to the DX !

addendum 1: just an example of a message posted on the chat (of course I have suppressed the callsign of the author)
"tnx good spots at first from zs,vk6 and t6.... rx/tx on g5rv 4m AGL" (this was on 80m ...)"
Did this OM realized (and several others using the same strategy ) that with his 4m AGL G5RV, High power and high TX-rate he was blowing-up all the receivers in a 1000kms circle around him ! A low horizontal dipole is a NVIS antenna, which is likely to produce very strong signals at short distances...
Btw the pbm is not only on 80m. It may happen also on higher bands, when E's condx are present. see: http://picasaweb.google.fr/lh/photo/okIoZfWpF1eGpT-rn_UBaw?authkey=Gv1sR...

addendum 2: During the same a/m 17m activity day I was still spotted >10dB while using 500mW... so QRP is not always the solution ! At least using 10% TX-cycle I hope I did leave enough clean time slots for DX-stations to be heard... Another good reason for using low TX-rate, is that you rarely get more than 6 stations decoded in the same period (at least with a quite old computer). When more than 6 stations are transmitting in the same period, the weaker stations seem to be "sacrified" by the decoder...

addendum 3: the ideal solution would be to leave specific periods for DX stations to transmit, but right now it would have to be done manualy... so it is far from being ideal, not to say utopic... The only solution, we have right now, is, for stations in high Ham-density to use 10% TX-cycle when the activity is high.