I see comments from very serious contesters about having a second “in-band” rig.  I assume it is to work mults while the main rig runs on the same band.  I couldn’t find much about how this actually works.  I’m not a serious contester, but I would like to think about how this could apply to Field Day, and things like group POTA operations.  Everyone wants to start out on 20 meters.  At night, 80 and 40 are the only usable bands for several stations.

Available bandpass filters and stubs work great for different bands, but passing 14.250 Mhz and attenuating 14.040 Mhz is a different ball game.  W2VJN’s book shows filters for 80M CW and 75M SSB, but those frequencies are separated  further.

I assume it is done with antenna spacing and polarization.  KL9A has a vertical for  the 10M in-band rig.  Cross polarization with yagis would give significant attenuation and spacing seems to be at least several hundred feet.  I’m sure the run station is QRO and the mult rig probably is more than 100 watts.   Is it as simple as antenna separation and type?

I doubt if I would try to actually implement any of this at FD because I’ve slowed down a lot on FD.  I’ve participated in over 50, and I still do some operating and never mind telling people how they should do things even if I know they aren’t listening :) I am interested in how it is done, though, and if there are any articles I should read.   

Ours has been hit or miss.  Sometimes CW can operate on 14.025 and FT8 can operate on 14.074 within 100 feet of each other, and sometimes there is interference.  Usually, when there is no interference, the rigs are Elecraft, newer Kenwood, etc.  Some very popular rigs almost always seem to suffer interference.  Maybe the type of rig is the main factor?  Maybe I don’t have a good understanding of what they mean by “in-band”.  I know both aren’t allowed to transmit at the same time, but I want to know how a rig can tune around 20 meters and copy signals while another station on the same site is running.

It always frustrates me when I can’t find any information on something I know is done.

73,

Dennis/RZ