Andrew (grayhat) wrote: ↑Tue Jul 04, 2023 6:38 am
Mike, you're looking at it just from the point of view of "nasty effects during transmission", that isn't the only way, let me expand it; first of all there's nothing like "power levels" when it comes to common mode currents, the point is that a feedline (coax) should work as a feedline and not as part of the radiating system, let's say we have a "random" wire antenna fed using around 17ft of coax and we don't use a choke nor a counterpoise, our coax runs on the ground for some length and then goes to the antenna feedpoint, now we start trasmitting with 5W and since we don't have a counterpoise the antenna will use the coax braid as the "counterpoise", the latter will at all effect act as part of the antenna so it will radiate, now when we trasmit, part of our 5W will be radiated by the coax and since it isn't exactly a good radiator and lays on ground, that part will be almost totally wasted (which isn't a good thing, we aren't putting out some KW
), if instead we place a choke after the 9:1 transformer and use a counterpoise, the coax will just work as a feedline and the antenna will radiate much better that little amount of power we are sending on the air
Hi Andrew,
I want to respectfully offer another perspective.
Context is important, so here is mine. I enjoy operating CW-mode QRP in the field, particularly for POTA. I describe my style of operating as backpack portable, meaning that I am easily able to hike with my station. Sometimes the hike is several miles, but can be short (as in operating from a table in a picnic area) or very short (as in operating from my truck in a parking lot). Another aspect important to my operating style, is the ability to rapidly deploy and tear-down of my station, so I can do multi-activation roves when desired. All of this means that I try to minimize size, weight, and number of components, while still getting my contacts.
With that background, I use both EFHW and EFRW antennas. I deploy them without using a choke, and often without any counterpoise except my 15 ft RG-316 feedline. I accept sub-optimum performance, including the losses, because it simplifies my station, while still letting me make contacts. I guess I should also acknowledge that detrimental effects on operation due to "RF in the shack" would cause me to change my configuration, but so far that hasn't been an issue at 5, or even 10 watts.
I take no issue with your technical assessment, but I want to clarify that there can be valid reasons to deviate from the optimum.
73 de Brian - K3ES