Anntenna Question

You do not have to have components connected or turn-on in various rooms of the house. The fact that you have all that wire going everywhere weakens the signal.

Let's take another look at the initial installation. That antenna is an omni (circular reception pattern) so as long as it's not mis-installed (somehow grounded to the mast) or defective, it should perform much better than the interior dipole. It likely has 300 ohm terminals (unless self-baluned with a coaxial type F connector) so there should be a 300 ohm to 75 ohm balun between the antenna & your coax type F connector. Make sure it's a single run of coax from antenna to tuner, with no kinks or tight bends, no splitters or anything in between. Any other coax in the house is then irrelevant. RG-6 coax is very good for this application so don't wory about that one bit. Weatherproof any external connections. On your receiver, connect the coax shield to that right "ground" terminal & the coax center-conductor to that middle "75 ohm" terminal. Ensure that none of the shield's fine wires are shorting to the center conductor (both inside & outside) that would kill the signal completely.
Using a multimeter (resistance scale) with the inside coax disconnected from the receiver you should be able to look into the cable & see that balun up top. It may appear to be 75 ohms (or perhaps considerably less impedance at DC) but there should be some continuity present.
Failing all that, your receiver's 75 ohm tap may not be working? Since you know the 300 ohm tap works with the dipole, try another balun inside & connect it to the 300 ohm inputs. Failing that you may even have a defective antenna? Try connecting it into a TV set tuned to mid-VHF channels 4, 5, 6 etc. to see if any signal at all is coming down the pipe. The FM band falls right in between there so if you have no TV signals then that probably explains the lack of any FM.

As always, Bob has analyzed the problem systematically. My gut, tells me the problem is in the multi-room coax installation; either in terms of multiple splitters (although that much coax would act as an antenna of some sort and you should get some kind of signal) or in terms of a break in the walls or at one of the panels. Either way, it seems to me that if you follow Bob's fault tree, you should be able to narrow the problem down pretty tightly.

I want to thank everyone for their responses, especially Bob for his step-by-step advice.

I went back to the cable that goes to the antenna, put an ohmeter on it (as Bob advised), and it's open. I can't "see" the Balun at the antenna. So something is not right in the antenna setup. The problem is not the cable in the house.

Now if I can figure out how the heck to get up on my sharply peaked roof!

- Eric

I just purchased a new VHF marine antenna and VHF marine radio for my boat. My question is, can I use the old VHF antenna by converting the end plug from VHF to AM/FM end plug and simply plug that into my old AM/FM radio? Put another way, is the signal from a vhf antenna usable for AM/FM? I know you can buy a signal splitter and use the output from the splitter for both types of radios. The splitter costs as much as a new antenna. My existing AM/FM antenna consists of a 3' piece of covered wire. Thanks in advance.