Hi Gary, As preface, you are in my CQ160CW log. And lest someone have the idea that the following is some kind of whining about QRP...
Particularly in a contest, I ENJOY trying to pull QRP stations out of the noise, especially the ones I can manage to copy and the next guy can't. Successfully working QRP puts points differential between me and those who can't. I just have to make sure that doesn't cause me to lose my run frequency. But let's be clear headed about what QRP lays on the other end and what the dB realities are. For sake of argument, make the assumption that a 1.5 kW station should be heard about as far as he can hear another 1.5k station. That would imply similar noise levels at both ends and equivalent RX ant provisions. Now place yourself geographically on either end of this station pair. 1500/5 = 300. Log 300 = 2.477. 10 log ratio = 24.77 dB, call it 25 dB. 25 dB out of the noise is 10 over S9 on a lot of S meters. In a few rigs, like the K3, the S unit display can be calibrated. K3 "S unit" leds are 5 DB. 25 dB would be 5 K3 leds. Right now my local noise on the S meter is tickling the S6 led. S6 plus 5 leds or 25 dB is just tickling 10 over 9. The 1.5k station would have to be a real 10 over 9 in order for the QRP station to just be right at the noise. 95% of the contest signals answering my CQ's last night were below 10 over 9. For the QRP station to be 5 dB out of the noise, the 1.5k station would need to be 15 over 9. In RBN terms, the 1.5k station would need S/N of more than 30 at a node local to the non-QRP end. Some things QRP stations do (some necessarily) make copy even harder. There is the myth that correct matching equipment for contest QRP is trail-grade, AKA teeny. Teeny tuners, with small wires and small jacks and often with 160 as a poorly engineered afterthought, will sometimes add 2 or 3 dB loss. The big QRO tuners are needed for their lack of loss. This is not a put-down for on-the-trail QRP signals, just a dB evaluation of same. Someone wants to run that, fine by me, just don't get on my case for not being able to copy. Know what you're actually putting out. QRP stations and teeny matching equipment are sometimes all that's possible in tight spaces, where one may have the same volume as a stack of five or six paperback novels to place the station. KX3's and all those kinds of things. Particularly so in family occupied RV's and similarly disadvantaged settings. The very short antennas and extremely sparse (therefore lossy) 160 counterpoises sometimes can have three or four dB loss (and more) compared to a well-counterpoised full size antenna. That and the teeny tuner get us up to the 1.5k station needing to be 20 over 9 for QRP 5 dB out of the noise. That certainly is my experience for much of QRP on 160. I have an email somewhere from a QRP station that was using a coiled antenna stapled to the basement ceiling, which was bare floor joists. He made something like a dozen contacts in a contest, myself being one. I'm not sure my ears are good enough for that any more. 73, Guy K2AV _________________ Topband Reflector Archives - http://www.contesting.com/_topband