Hi Eric

I certainly welcome your question, amateur radio related or not!

Most effort in amateur radio circles on MF is associated with matching a
transmitter and antenna. The next most important step is to increase the
desired signal to noise ratio into the receiver (by using antenna
directivity, type and orientation etc) Since atmospheric noise is far
stronger than that contributed by the receiver device, actual signal
loss over the feedline length isnt normally an issue. The actual signal
level isnt important provided it is greater than the noise.

1. Under perfect conditions assuming known source, load and feedline
impedences, yes the power going to each receiver will be cut by half
(3dB). Purist may argue that a simple "in parallel" configuration is a
bad thing. For AM MF I dont think you'll even notice it...

2. I doubt the balun to RG6 would be useful. I'd also suspect they will
be hard to find given the operating frequency. (Cheapo TV baluns
probably wont work well much below 40MHz) One of the problems you will
encounter coax or ribbon is that if the antenna isnt symmetrical you
will receive noise from along the length of the feedline itself. Not a
good thing if it runs past a fluro or light dimmer (or wiring).

I also doubt that the input Z at the antenna input terminal truly is 300
ohms. I mean it works over a 3:1 frequency range as well..

One of the downsides of using ribbon is possible interactions with
nearby metalwork. I'd suggest in your case that it wont be an issue. In
fact using the supplied loop antenna may be no better than using a
random length of wire (dipole arrangement) attached to the ends of the
ribbon in the attic. The line loss is not so much an issue than the
signal received at the antenna itself.

I'd suggest you use the random wire approach with the ribbon in parallel
to both tuners and see what the signal is like. If it is still noisy
play with the antenna polarity (vert vs horiz or at least diagonal) I
suggest that trying to match impedence and getting the same signal power
in each line/RX isnt important at all. If one wanted a perfect
configuration (ie for transmitting) the difficulty is major given the
frequency range the thing has to work over.

Tell us how you fair

Cheers Bob W5/VK2YQA East Texas


Eric wrote:
This is a series of questions about AM broadcast antenna and lead-in
problems I have, it is not a strictly "amateur radio" question, so I hope
you forgive the intrusion but I thought this group to be the best for the
question.