wrote:

On Nov 17, 7:51 pm, Tony Giacometti wrote:


This link was the guide I used to build the loop, I am only using the 80
meter loop.

http://www.qsl.net/kc2tx/

Without the preamp I do get a noise spike when I tune the cap.
Its very noticeable also.

I would have thought that the signals I have heard would be much louder
especially using the preamp.

They will be down, but the overall s/n ratio is what really counts.


I have 2 different types of preamps and they both behave the same way.

For what its worth, I have never considered just plain wire for the loop.
I do use coax RG-6 - its all I can get, no RG-59 around here.
Another ham mentioned to me that using 75 ohm hardline would be the best.
None of that stuff here either.

the hardline would be used for the loop, sorry if I didn't make that clear.


Type of coax should matter little if any.. Hardline would be a waste
of time I would think.


I am beginning to think my feedline could be a problem. I can replace
that stuff rather easily.

Not unless you have a common mode/ noise pickup problem.
And changing to another run of coax alone is unlikely to help that.

I had a defective run of coax running to an antenna.
Not sure if I mistakenly used it for the loop.



I like your idea of a separate coupling loop.

Any idea what the loop would need to be electrically and physically?
Do I need to change my tuning cap if I change to a coupling loop?

No. The main loop will still be tuned to the same frequency, no
matter if direct fed, or with a coupling loop. Many people build BC
loops and use the ferrite bar antennas in the portable radios
themselves to couple to the loop. But my radios are not portables,
so I use a coupling loop fed with coax.

MK

how do I calculate the dimensions of the coupling loop?