OT: A caution related to external low-pass filters … Many were made with cutoff frequencies -below- 6M and these exhibited high reflected power above 10M.
Trivia, FWIW 73! Ken - K0PP On Sun, Feb 17, 2019 at 4:26 PM Don Wilhelm <donw...@embarqmail.com> wrote: > A low-pass filter will not change RFI either coming into the shack or > going out. There are low-pass filters in all transceivers produced by > Elecraft (and most other manufacturers), and they are in both the > transmit and receive path. > The current FCC requirement is for the 2nd harmonic be suppressed by 43 > dB over the fundamental. > Low pass filters come from a past era when the FCC requirements were not > as stringent and TVs responded to those higher order harmonics from > amateur transmitters. That is no longer the case. > > Considering receive, we do have many sources of unintentional radiation > which is present in the HF spectrum, and other than locating and having > the offending device turned off, there is not much we can do about it. > Although if it is interfering with licensed operation, there is recourse > by cooperation with the FCC. The products giving problems range from > inexpensive switching power sources (read wall-warts) to control > circuits in many household appliances and other consumer devices, and > even some lighting products. > > If you are operating in an environment like Field Day where there are > multiple transmitters operating in close proximity, bandpass filters and > single band antennas are the normal "cure" as well as physical > separation of the antennas. > > 73, > Don W3FPR > > > > On 2/17/2019 5:59 PM, Richards wrote: > > Good day - What is the consensus concerning low-pass filters to > > minimize RFI both coming in and going out of the shack? Is there a > > type or size, brand or model that comes highly recommended? Is it > > prudent to employ one, regardless of whether or not there is a known, > > identified problem , i.e., just in case? Does it assist reception as > > well as transmission? > > > ______________________________________________________________ > 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 kengk...@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
