It isn't exactly true that NF is unimportant on tropo.... otherwise no one would be using a mast mounted preamplifier..... The main issue then is preserving the dynamic range, as you pointed out.... On the XV144 module is mandatory to remove the second rx stage to do that in this case. The point is, how many stages the new module have? Is the second one (I assume that it is there) easily removable or bypassable? About the dynamic range I didn't completely agree with the Elecraft first choice to use a 50 MHz IF, and the second one with 28 MHz isn't much better imho. Ok, I'm a little selfish here, but the serious contesting machines (Javornik, DB6NT and others) use 14 MHz and there are couple ofgood reasons to do that. Usually the HF radios have their better spesc in terms of BDR etc. on the 20 mt band, and likely the K3 is no different (Wayne, Eric, can you confirm?). The image frequency on 28 MHz IF is in the FM broadcasting band (88-108 here), and I must use a cavity filter between the LNA and the RX port of the xverter, or I get a lot of crackling noise and birdies, as well as good fm music. The only real disadvantage in this case (14 MHz IF) is that the band is somewhat limited by the 14 MHz limits, but for a 144 MHz contester/Dxer, the portion of band really important is on 500 KHz, from EME to beacon band 144.000 to 144.500.
These are my two cents on the topic. 73 de Giulio IW3HVB AD6XY ha scritto: > It is nice and low but 1 dB is not exactly cutting edge. I will measure mine > when it arrives on some high spec equipment. It does not really matter that > mush though on 2m. For terrestrial use the band noise is the limit, for EME > anyone serious will be using a low noise pre-amplifier. > > What is much more important to operational use and what I would like to know > is the dynamic range. Is it over 100 dB at 3kHz spacing like the K3 on HF? > What about the intercept point - is it better than 20 dBm? It needs to be > here in Europe! There are 4 high power stations active in my grid square, > i.e IO91JO and blocking is an issue with the XV144/K3 combo. > > Mike > > > ______________________________________________________________ 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
