I understand we are speaking about the KX2 here but I'm curious... would roofing filters have helped in this situation?
In a recent WWFF outing we had a KX3 and an FT-817 set up. We separated the antennas best we could but really didn't pay a lot of attention to it. I believe the KX3 was on 40 and the 817 on 20 meters. The KX3 never heard the 817 but the 817 (no roofing filters I think) washed out when the KX3 was keyed. The radios were about 30 feet apart and the antennas maybe 40-50 feet apart. If the KX3's success was due to the roofing filters installed, could some sort of external filter added to the KX2 contribute to a solution? Is the KX3 meant to play well with others while the KX2 is intended more for a solo trip? I understand W4RT has optional roofing filters for the FT-817. I wonder if he or someone might come out with a good option for the KX2. Then again... am I way off base here? 73, Kev K4VD On Sun, Apr 16, 2017 at 2:08 PM, Fred Jensen <[email protected]> wrote: > At 30-40 ft separation on 15 and 20, your two antennas are probably within > each other's near-field and each is thus "part" of the other. The coupling > in the near-field can be very high. The general rules are: > > 1. Separate the antennas by as much as possible, preferably several > wavelengths. A wavelength on 20 meters is ... well, ~20 meters [roughly 67 > international feet]. > > 2. Orient/position the antennas such that one is in the other's null. > For half-wave dipoles, that's off the end and FD experience suggests > colinear with each other and well separated works best. Note however, if > they are within each other's near-field, orientation may have little if any > effect [see #1 above]. > > During the BPL bruhaha a number of years ago, I modeled my my non-resonant > sloping-V and a couple of 12 KV distribution lines [which would have been > the BPL carrier] together using NEC-2, similar to K9YC's suggestion, to see > how badly I would disturb my neighbor's BPL I'net if he had it. The > coupling coefficient on 40 meters and higher was pretty stable at around > -30 to -35 dB. On 80 and 160, where the power line and antenna shared a > near-field, the coupling was in the -10 to -15 dB range. > > As you describe them, and with perhaps 10 watts for easy math, the > received power might be one or two tenths of a watt. It's not real > surprising the receivers "cried out in pain" [:-). > > 73, > > Fred ("Skip") K6DGW > Sparks NV USA > Washoe County DM09dn > > On 4/16/2017 9:44 AM, kevino z wrote: > >> A friend and I both had our KX2 transceivers and some resonant end fed >> antennas. He was on 15m and I was on 20m. Our antennas were placed about >> 30-40 feet apart, as slopers with the radiating ends up 30+ feet in the air >> using Jack-kite poles. The plane of the antenna's slope were perpendicular >> to each other. >> We were both on 10w SSB. >> >> Every time one of us keyed up, the other person's KX2 would experience a >> nasty noise from the signal. Pre-amp was off, as was attenuator. My >> question is this: Would the use of some bandpass filters have helped us? >> This is a situation we are trying to resolve before operating QRP in a >> similar park for a QSO party. >> >> If more distance between the antennas would have helped, what is the >> proper way to determine the needed separation? >> >> I read the other day about someone in a car using 3 or 4 Elecraft radios >> with antennas on the roof, so I imagine there has to be a way. >> >> Thanks, >> -Kevin (KK4YEL) >> >> > ______________________________________________________________ > 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 > Message delivered to [email protected] > ______________________________________________________________ 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 Message delivered to [email protected]
