One fact that does seem to get missed by many 6m operators is that ambient noise is very much relative to where you are. Dick makes this very clear. The old test of disconnecting and reconnecting your antenna to see if the antenna noise level is perceptible is a good rule of thumb -- but that's all. Noise is additive. If you have a front end with a crummy noise figure on 6m, but you do hear the noise level increase modestly when you connect the antenna by a couple dB -- you will *still* probably benefit from a preamp with a much better noise figure, because the receiver-based noise you were hearing with the antenna disconnected is a significant portion of your overall noise floor when the antenna is connected.
On the other hand, if your total noise floor goes up 7-10 dB when you connect the antenna, that's perhaps a different matter. This is how much *my* noise level goes up -- on a *good* day. Will I benefit from a super-low-noise preamp, as did the CY0X expedition? Maybe not so much. :-) Again, it depends on how much my existing receiver is contributing to my overall ambient noise floor. All I can say to those guys who need 20 dB of gain and a hushed noise figure to be able to hear any antenna noise on 6m... I envy you more than I can say! My guess is, however, that my situation is more comparable to the vast majority of 6m hams living in a typical US metro area. The whole point of this is simply that the question of "how much RF gain is enough" and "how good a noise figure is good enough" is *extremely* relative. I wish it weren't so, but that's the reality. The only reliable way to see if an LNA will help in your situation is to try it. Which is exactly what I plan to do. :-) Bill W5WVO ----- Original Message ----- From: "Dick Hanson" <[EMAIL PROTECTED]> To: "'Stewart Baker'" <[EMAIL PROTECTED]>; "'Elecraft Reflector'" <Elecraft@mailman.qth.net> Sent: Tuesday, July 01, 2008 3:19 AM Subject: RE: [Elecraft] K3 6-meter Performance Question > Ciao, from CY0X, Sable Island..... > > Well, let's see now, is the K3 sensitive enuff for serious weak sig work on > six. > Based on our first week here on Sable, doing mostly weak signal work, I > could not be more pleased. > We were fortunate to have been given one of the prototype preamps to use > ahead of the radio on six, and I can tell you that it has been an excellent > addition. > We have been monitoring many of the EU TV offsets, world-wide beacons and of > course listening for many of the signals from across the pond. > > Consider this: we are running approx 800 watts into a 12dbd ant at 70' ASL, > surrounded by salt water; we have zero man-made noise towards EU, AF and > Asia, so we are hearing very well. Many of the stations we are working in EU > do not have as much power or antenna; hence many of them hear us better than > we hear them. Yet, we have logged nearly 2500 contacts thus far in 60 dxcc. > My conclusion is that we are not suffering from a hearing loss. > > Since it is so easy to switch out the outboard preamp, we have frequently > done this on some of the weak sigs just to see if we could still hear them. > In many cases we could hear them Q5 with just the internal preamp. Ian, > GM3SEK, et al, have pointed out that the stock radio NF is somewhere in the > 8-10db range, which is not stellar as six meter radio specs go. Nonetheless, > you'd be surprised at how many weak sigs we can still hear with only the > internal preamp engaged. > > I also have the XV50, and will keep it, but that is because I tend to keep > my radio gadgets a long time. > > FWIW: we love the K3 and how it performs on six. Hopefully, we have already > worked a number of you. If you haven't yet made contact, please check our > website at www.cy0x.com and then stop by 50108 and give us a call. > > 73, > Dick > K5AND/CY0X > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
