On Tue,3/22/2016 4:50 AM, george allen wrote:
RF is getting into your equipment.
While this is not the only possible cause, it's likely. Other possible causes include a bad piece of coax or bad DC wiring.
RF split cores on all leads into your 2820 should solve the problem.
If the problem is simple overload of the 2820, what is needed is NOT simply slipping a split core over the coax from the 2820, but rather multiple turns of the coax through a #31 or #43 Fair-Rite core. That could be a split core or a toroid. If it's a split core, five turns is a good start for 40-10M, one or two more if the problem is from 75M. If it's a toroid, I would start with 5 turns for 20-10, 7 turns for 40-15, 10 turns for 80-20.
Also, think about antenna locations. Are the HF antennas and 2M antennas close together? Separating them a bit could help. And the HF antennas should all have a multi-turn coax choke at their feedpoint (that is, up in the air).
RF interference is NOT solved by a connection to earth. RF interference CAN be solved or reduced by bonding together every piece of gear in the shack with short, fat copper. That combination of chassis DOES need a bond to all other grounds in the building, both for safety and for reduction of hum, buzz, and RFI.
And even though John said he had "checked" all the coax, a bad piece of coax (either the cable or the shield connections) should be suspected as a possible cause.
Study http://k9yc.com/GroundingAndAudio.pdf for lots of detail on this. And study k9yc.com/RFI-Ham.pdf for a tutorial on how RF gets into equipment, how ferrite chokes work, and how many turns on which ferrite cores to use for different situations.
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 arch...@mail-archive.com
