I think most people are actually building their K9AY loops to use 75 ohm coax
these days as that is the standard "receive coax". The only change you need to
make is the winding of the isolation/matching transformer at the loop. Many
will even tell you that it's not all that critical even there. If you're
sending DC power through the coax that part won't change for 50 or 75 ohm coax.
On my system, I would the transformer at the loop to match to a 75 ohm cable.
Inside, I have a preamp with some switchable attenuators that I built and it is
matched to the 75 ohm coax on the input (via a matching transformer wound on a
small binocular core), the output is 50 ohms for the radio. Many will tell you
the 75/50 ohm matching on this end isn't all that critical either.
Probably the easiest way to go is to wind the transformers to use 75 ohm
feedline if you're making them yourself, and if you're using premade units you
can probably get buy without worrying about the slight mismatch.
-Bill
> As soon as i have th radials under the Inv-L i was considering
> constructing a K9AY rcv loop system. The best/easiest place to put it is
> actually jsut out side the shack , but , I am wondering if the 2 story
> house (about 30 ft away from the loop) between the loop and basically EU
> will have much effect on the loop ? I can put it out on the open but ,
> that will be a little more difficult.
>
> Also , I have a large supply of RG6 CATV feedline which I believe is 75
> Ohm ? what modifications do I need to make to use it rather than a 50 Ohm
> feedline...
>
> Thanks
>
> Dan N8DCJ
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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