> All that said, Bill is correct that, with the matching fee, > the price difference between 5-pole and 8-pole filters is > small enough that it makes sense to get the 8-pole filters.
This is particularly true if you are buying multiple filters. With the discount for three (5%) or five (10%) filters, the direct route is less expensive than including the filters with the transceiver. > I would get the 5-pole 200 Hz filters. Elecraft says they're > narrower than the 250 Hz filters all the way down. Close enough ... measurements of my 200 Hz filters "in circuit" show 210 Hz @ -6dB and 840 Hz @ -50dB (I need to repeat the measurements with the preamp to extend the range) versus the published data (www.elecraft.com/K3/K3_8_pole_plots.htm) for the 250 Hz filters: 370 Hz @ -6dB and 785 Hz @ -60dB. 73, ... Joe, W4TV > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Dick Green WC1M > Sent: Saturday, July 25, 2009 1:30 PM > To: 'Bill W4ZV'; [email protected] > Subject: Re: [Elecraft] K3 160M Diversity Users > > > My experience pretty-much aligns with Bill's. I started out > with matched pairs of 5-pole 500 Hz and 5-pole 200 Hz > filters. The 500/200 combination makes a little more sense > than the 400/250 combination because there's more difference > between the filter widths. > > Like Bill, I rarely use the 200 Hz filters. Most of my use is > contesting. If you spend too much time with BW cranked down > to 200 Hz or less, you're going to miss a lot of callers. I > only use narrow BW when someone plops down very close to my > frequency when I'm in the middle of a QSO. That said, the > narrow BW saves me every now and then, which for me is worth the cost. > > I was fairly satisfied with the 5-pole 500 Hz filters, but > was sometimes bothered by thumping and clicking from loud > stations (S9 and higher) just above my passband. This is > likely caused by the hardware AGC activating at somewhat too > low a level. Quite a while ago there was a fix to the RF > board to raise the threshold, but some of us think it's still too low. > > At any rate, though the theory says that roofing filters > aren't responsible for the ultimate selectivity (the DSP does > that), I found that they do make a difference in the above > situation. Switching off the 500 Hz filters and using the 200 > Hz filters produced audibly less interference, most likely by > providing greater attenuation at the hardware AGC stage. That > induced me to replace the 5-pole 500 Hz filters with 8-pole > 400 Hz filters. > > The result was a minimal improvement, not easily detected by > testing. The real test will come this fall when I'm squeezed > into 40m or 20m with zillions of loud stations on either side. > > All that said, Bill is correct that, with the matching fee, > the price difference between 5-pole and 8-pole filters is > small enough that it makes sense to get the 8-pole filters. I > should note that the 8-pole filters are not necessarily > perfectly centered, but they're close enough that you > probably won't need to use any offset for diversity. > > As far as the 200 Hz vs 250 Hz filters go, if you want to > have them in reserve for those really tough QRM situations, I > would get the 5-pole 200 Hz filters. Elecraft says they're > narrower than the 250 Hz filters all the way down. Also, > there's more BW difference between the 200s and the 400s/500s. > > I agree completely with Bill on the merits of diversity: with > the right antennas, it's amazing. > > 73, Dick WC1M > > > -----Original Message----- > > From: Bill W4ZV [mailto:[email protected]] > > Sent: Friday, July 24, 2009 10:27 PM > > To: [email protected] > > Subject: Re: [Elecraft] K3 160M Diversity Users > > > > > > W4UM wrote: > > > > > What are your recommendation if I were to get only > > one pair of filters? > > > > I would go with either the 500 or 400 8-poles. > > > > > Is there any real value to getting a pair of narrow > > (200Hz or 250Hz) filters as well as a pair of the wider (400Hz or > > 500Hz) > CW > > filters, or am I just wasting money? > > > > I have a 200 Hz in my Main in addition to 500 Hz 8-poles in > Main and > > Sub. If you contest or are in huge simplex pileups, there are > > definitely times when the 200 Hz may be useful. For some reason I > > don't understand, I have no offset warbling when setting > WIDTH to 200 > > (which enables the 200 Hz in Main and 500 Hz in Sub). Most of the > > time when listening to weak signals, > I > > use 350-500 Hz WIDTH so a pair of 500 Hz filters is fine > excluding the > > extreme cases of simplex pileups or a strong station nearby > (e.g. the > > CQ > 160 > > CW contest). > > > > > Is there a noticeable difference between the 5-pole and 8-pole > > > filters? > > > > I used 5-pole 500s in my first K3 and have not noticed a > significant > > difference with the 8-poles, but I've not compared them > > simultaneously. > As > > you stated, there's little cost difference (after the > matching charge) > > so > I > > went with the 8-pole 500 Hz when it became available. I personally > > prefer > a > > slightly wider BW than the 400 Hz allows but that's another option > > some choose. > > > > You'll love diversity on 160 and 80, especially if you have good RX > > antennas. I use my TX antenna (similar to a 4-square) in > one RX and > > Beverages in the other, and I use diversity 99% of the time > on the low > > bands. I would never own any rig without diversity now > that I've used > > it. > > > > 73, Bill W4ZV > > -- > > View this message in context: > http://n2.nabble.com/K3-160M-Diversity-Users- > > tp3322951p3323855.html > > Sent from the Elecraft mailing list archive at Nabble.com. > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
