When you buy RA6LBS filters each comes with a tracing by a spectrum analyzer showing the exact filter characteristics. On each of these that I own the tracing matches the Rigol with tracking generator. They really work well. I have a complete set of 500 watt filters from RA6LBS. They are sold by DXengineering. My other set is VA6AM they also provide 80 to 100 dB of rejection with a 3500 watt rating. The cost of those filters with switch, multiplexers and cabling is more expensive than many people have invested in their radio alone.
In conclusion, investing in a heavy duty set of filters is cheaper than blowing up a radio. Plus, it gives one more options. 73, Morgan NJ8M BS + MS + $2.98 = COFFEE Real Life Experience = Priceless, says the man who set his back yard on fire with a breadboard tuner loading a 160 meter inverted L with 1000 watts. LOL On Tue, Jul 27, 2021 at 9:55 PM Jim Brown <j...@audiosystemsgroup.com> wrote: > On 7/27/2021 12:53 PM, Morgan Bailey wrote: > > 80 to 100 dB band to band attenuation is necessary for a contest station. > > That depends a LOT on the radios and the amps. > > > Reviewing Contest University the RA6LBS talk from a few years ago is the > > basis for this decision. He probably has the most experience in this > field > > beside that of VA6AM. Both make great filters. Just having a filter is > not > > enough. One needs a multiplexer in conjunction with the band pass filter > to > > get to that DB level. One could stack 2 band pass filters and attain > > whatever is needed to get the job done. The multi switchable boxes that > run > > about 500 to 900 dollars only give about 30 to maybe 40 db of rejection. > > That also depends a LOT on the boxes, and some are far better than > others. See this study I did about 8 years ago for National Contest > Journal. http://k9yc.com/BandpassFilterSurvey.pdf Several of the units > are 10-20 dB better than that. > It > > is just not enough to keep the other radio quiet and SAFE from front in > > overload and toasting the receiver circuits. I use transmitting band pass > > filters rated at 3500 watts on the output of my amp. > > This is a very good way to do it. Most hams overlook the harmonics and > IMD generated in power amps. > This coupled with > > multiplexers on 160/80/40 and 20/15/10 makes for a multi two or an SO2R > > setup quiet on each radio. Between the multiplexer and associated band > pass > > filters I am able to run 1.5KW 160-10 with an antenna farm that takes up > 68 > > linear feet total for 160-10. Additionally, 160/80/40 are vertical > > polarized and 20/15/10 are horizontal polarized adding more rejection. It > > works and works well. > > > > One problem that many stations on a small lot have is ignoring Common > Mode > > pick up off the shield of the coax. Grounding all shields before entering > > the shack > > YES! AND seriously bonding everything in the shack and the building that > contains it. > > and using 1:1 choke baluns is a necessary step to prevent > > interstation interference. > > Yes, it's quite important to have a SERIOUS common mode choke at the > feedpoint of EVERY antenna. http://k9yc.com/2018Cookbook.pdf > > > > Having radios with very low composite/Phase noise is necessary. > > YES! > > At the last Visalia DX Convention, gave an overview talk on a dozen or > so mechanisms that contribute to inter-station interference, and how to > minimize each. It's here. http://k9yc.com/Multi-Station.pdf > > And W2VJN's book on the subject is excellent. > > 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 > Message delivered to mbaileyc...@gmail.com > ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
