Hi Jim, Thanks for your testimonial. By any chance do you have means to measure the isolation at your qth in dB?
My setup has already evolved to 7/8 andrew hardlines, silver plated shell and pin connectors, etc. I have 4 7/8 and 2 1/2 coax lines entering into shack into a big 4 inch galvanized steel pipe (I think you know where I learned about it.. hihi). I measured the RX antenna coaxial and it has no discernible common mode signals flowing in. So far I´ve got 80db isolation in worst case, but I have some all band mush when transmitting in SSB. CW is abit clearer. Anyway I´d like to know how to derive this figure from power output in dBm and, I guess, published IMD figures. 73, Felipe Ceglia - PY1NB ------------------------------------------------------------------------------------- PR1T team member /// Rio DX Group member /// Araucaria DX Group member http://dxwatch.com /// http://reversebeacon.net /// http://riodxgroup.com On Fri, Sep 14, 2012 at 1:46 PM, Jim Brown <j...@audiosystemsgroup.com>wrote: > On 9/14/2012 6:59 AM, Felipe Ceglia wrote: > > In a in band two K3 scenario (100w, no amp), how many dB's of insulation > > would be needed between each rig's antenna connector in order to keep the > > RX clean? > > I can tell you what I do, and I can run two K3s into 1,5kW Titan amps > into beams separated by about 180 ft on the same band. Depending on how > the antennas are pointed, I can be within 60 kHz one K3 doesn't know the > other one is there. For example, when I point the two antennas to the > ENE (the east coast of the US), they are at right angles to each other. > If I point one antenna at the other, the radio will usually be > overloaded, the preamp will turn off, and the attenuator will turn on, > but I can often hear strong stations and work them in between > transmissions by the other rig. As an example, I might have one antenna > pointed east and the other one NNW to work KL7 or UA0. > > Another important part of the equation is feedline. The long runs to my > antennas are mostly Hard line, and all the other coax in the system > (including jumpers in the shack) is very high quality RG8 (similar to > LMR400) with a robust copper braid plus foil shield. All of the > connectors are Amphenol 83-1SPs, all are carefully soldered, and all > connections are tightened with a wrench > > Each year, I'm part of a group that takes our K3s to a remote county for > the California QSO Party (coming up in a few weeks). Our setup allows > spacing of about 150 ft between two tri-banders, carefully located so > that when we point them ENE (about 70 degrees, which gets us the East > Coast, EU, and the Caribbean) they have a null to each other. We use > our K3s with 600W amps, mostly KPA500s, but also sometimes a Yaesu or a > Ten Tec Hercules II. With this setup, we can have a CW station and a > SSB station on the same band and work signals down to about the S5-S6 > level. To work weaker signals one of the stations has to switch bands. > The primary difference, I think, are the feedlines, which are made from > coax pooled from several members of the team. Some very good cables and > connectors, some not so good, some connectors crimped rather than > soldered, some good soldering, some not so good. > > 73, Jim K9YC > > > ______________________________________________________________ > 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
