Re: Hoop Loop Demo on Youtube


sdwillingham
 

Glad to hear of your good results. The change in peak signals is especially interesting and corroborates my warnings about the sensitivity of the high-impedance wires on the secondary side. Any exposed wire has a strong resonated whip effect. This increases signal strength, but proximity to the radio makes this e-field pickup noisy. Plus it's a null spoiler.

Keeping the secondary coil and wires short and/or shielded is important for the optimal "hoop loop experience."

-Scott-

--- In ultralightdx@..., Chris Knight <radiodxerguy@...> wrote:

Scott,

I did what you suggested and connected the radio's RF GND (antenna low) to the aluminum box and it made a HUGE difference! I can null all my locals to some degree and in many cases they can be completely nulled. Nulls are not pinpoint, rather they are broad. So, if I null a station on skywave it stays nulled with no need to readjust the antenna. Your other suggestion of shielding the "hot" side is the next thing I'll try. The zip cord I'm using now has the RF GND side up against the "hot" side. That probably helps some. If I can do better with small coax just for the "hot" side then I'll try that as well.

At this point the Hoop Loop is very effective as a DX antenna. For example, I nulled local pest 910-KPOF and heard KINA also local 1490-KCFC was nulled yielding KGOS and KXRE. Audio is pleasant since there isn't much noise pickup. The Hoop Loop actually makes listening to GY channels (1230,1240,...,1490) pleasant! I can understand most of the audio now. Nulls are symmetrical, deep, and broad. I did notice peak signals aren't as strong now after connecting the RF GND to the box. They're probably down 3-5dbu as measured on the PL-380's display. The reason for this has to be the unwanted pickup from the 2.4" core is now gone and no longer adds to signals received by the antenna. The 23" size hoop is perfect, IMO. I wouldn't want to go too much smaller. Jim, have you built one up on a smaller form yet?

Chris

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