I think that for serious Dxers, 6 db can make a huge difference. I have a KPA500 and a KW amp. I tend to use the 500 watt amp for casual contesting and Dxing. But I find that I often have to turn on the KW when I am working very weak signal DX or when I am trying to bust a big pileup. For example, I have an inverted L on 160M (and have worked 99 countries over the last three winters on top band). I am finding this winter that when an EU station can't hear me with the KPA500, the station often comes right back when I turn on the KW amp. The same goes if I am attempting to work a weak Asian sig on the higher bands. In short, when you are dealing with weak sigs just barely audible above the noise threshold, 6 db makes a big difference! You need that 6 db even more when you live in western KY!
Dave, N4QS -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net]On Behalf Of Alan Bloom Sent: Tuesday, January 17, 2012 6:30 PM To: Vic K2VCO Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] KPA500 (another view) Very true. But even 6 dB would not make a big difference for a rag-chewer or a casual contester. Even for a fairly serious DXer, being in the right place at the right time and having superior operating skills are more important than an S-unit of signal strength. The place where the best possible signal is really essential is for a world-class contest station. Those guys agonize over every fraction of a dB of feedline loss. Alan N1AL On Tue, 2012-01-17 at 16:20 -0800, Vic K2VCO wrote: > Keep in mind that it all adds up. If you get 2 db more from your beam, and 3 db from going > from 500 to 1000 watts (say), and maybe a db by replacing your old coax, etc., that's 6 db > -- a huge advantage. > > On 1/17/2012 4:15 PM, Alan Bloom wrote: > > Interesting experiment Dave. I think that kind of test is valid for VHF > > operation. But on HF it is very rare to hear a signal at a constant > > level like that. > > > > Normally signal strength varies considerably from moment to moment due > > to fading. Even if the average signal level is right at the noise > > level, most of the time it will be well above or well below that level. > > A dB or two increase or decrease will vary the percentage of time the > > signal is copyable, but only a little. The QRM also varies in signal > > strength from moment to moment. > > > > Of course, louder is always better. But unless you are a big-gun > > contester, where winning or losing depends on a few extra contacts over > > the course of the weekend, I think you'd have a hard time noticing a > > couple dB difference in normal operation. > > > > I am just about to order a 2-element SteppIR Yagi. I decided that the > > extra dB or two of the 3-element model is not worth another $450. :=) > > > > Alan N1AL > > > > > > On Tue, 2012-01-17 at 16:52 -0700, David Gilbert wrote: > >> A power ratio of 3 (1500 watts versus 500 watts) is just under 5 db. > >> Check out these audio files (CW, though ... not SSB) I generated to see > >> what kind of impact that can have for readability of signals near the > >> noise threshold. > >> > >> http://www.ab7e.com/weak_signal/mdd.html > >> > >> 73, > >> Dave AB7E > >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
