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Anntenna Question

Hi,

I recently had electricians put a Radio Shack FM antenna on my roof. It's wired with RG-6U cable through a couple of patch panels down to where my receiver is located. Probably about 100' of wire in all.

It doesn't help reception -- in fact, I've gone back to the little wire dipole anenna that comes with the receiver because it sounds better. I put a little Radio Schack antenna amplifier in the mix about 10' from the antenna, and that doesn't help either.

The problem is that I don't know of any way to check whether there's actually a signal on this wire! I have access to bench-quality DVM, but that's about it. Would I require an oscilliscope to check?

I'm also not sure this is the right type of wire, or that I'm hooking it to the receiver correctly.

Any advice appreciated. Thank you!

- Eric
ehart
ehart OP
215 posts
 
Hi Sean, thanks for your reply.

Any thoughts on how to "read" a signal off the cable? I guess I could just haul the receiver around the house!

The receiver has three antenna posts on the back. The middle one is for both types of antenna.

The right post is marked "GND" and is used with the middle one for a "75-ohm" antenna.

The left one is used with the middle one for a "300-ohm balanced" antenna. That's where the dipole is hooked up now.

I believe I've tried both of these, in all combinations. It's been awhile though. Basically the shield of the coax to one terminal and the core to another.

- Eric
sugarbrie
3,854 posts
 
I agree, there is something very wrong (probably no signal). The ground is for AM. The 300 ohm is the FM; should be 2 connections. The Dipole is 300 ohm Are you sure the 75ohm is being converted to 300ohm? You need a proper adapter connected to the 75 ohm RG6U to convert it to a 2 wire 300 ohm connection.
swampwalker's avatar
swampwalker
5,138 posts
 
Eric- Check your receiver manual if you have it, but I am pretty sure that the 75 ohm tap on the receiver should be connected to the coax, and probably has an F connector for that purpose. If you have one of those "transformers" that comes with a VCR, you can connect that to the end of the coax and then the twin leads of that to the 300 ohm tap on the receiver. If that works, then there is a problem in the receiver with the 75 ohm tap; if it doesn't, then you are probably getting no signal. The first place I would check if that turns out to be the case would be the patch panels (why are they there?).
ehart OP
215 posts
 
Thanks for the tips guys, I will give them a try (additional are welcome of course!).

The patch panel is because I very cleverly (so it seemed at the time) wired my house with RG-6u to every room a few years back (while I was wiring for data).

- Eric
swampwalker's avatar
swampwalker
5,138 posts
 
Eric- do you know if all of in-wall RG6 is intact? Could be your problem, antenna is basically a passive device. BTW, if you are able to get a halfway decent signal with the dipole, then you shouldn't need an amp on the rooftop and signal should be very good (unless you got a directional w/o a rotor).
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