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AM FM Hidden In-Cabin Antenna

7K views 13 replies 9 participants last post by  merc2dogs 
#1 ·
I just installed a sweet little Fusion MS-RA200 stereo head in my CS27's main cabin. I installed one of those cheap pieces of wire that has an antenna bayonet on one end. I would consider the reception to be "OK", but not great. AM seems worse than FM. It also seems very sensitive to orientation and placement, neither of which is easy to control behind the panel.

I have a few requirements for the antenna, which I recognize may not be optimal for anyone else, but here they are:
- I don't want anything mounted (suction cup/sticky) on the cabin ports.
- I don't want to pierce the deck or bulkhead for this.
- I'm not interested in a VHF splitter.
- No additional mast antenna - this has to happen in the cabin.
- Must be possible to hide behind panels.

Seems to me it should be possible to get good reception under these conditions because I've had portable radios in the boat with telescoping antennas which worked fine. I'm ok with making something, or buying something.

Are there any recommendations on antenna orientation (does horizontal/vertical matter for AM/FM?), length, cabling from stereo to antenna, etc? There has to be a HAM expert out there who knows how to make a good antenna work in the cabin...

Thanks in advance,
Chris
 
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#2 ·
Chris, for AM you want a plain vertical mast/whip. For FM...one of those "T"s made up from some twin lead, often packaged or sold with home stereos. But as a compromise for both you'd use a vertical whip because anything horizontal will be directional.

Go to a junkyard, for five bucks get an old fashioned car whip antenna complete with cable and plug it in. Find a way to keep it vertical. Compromise on whatever you need to, ti won't get any better unless you buy one of the new amplified (needs power) shorter whips or something fancy.

Maybe you forget, radios with whip antennas, portable shortwaves, tv sets, you always have to fiddle around with pointing the antenna whip. Cars with plain vertical whips? Best compromise.
 
#8 ·
Go to a junkyard, for five bucks get an old fashioned car whip antenna complete with cable and plug it in. Find a way to keep it vertical. Compromise on whatever you need to, ti won't get any better unless you buy one of the new amplified (needs power) shorter whips or something fancy.
That's what I was sort of gravitating towards. I figured I could pick one up cheap and mount it along the bulkhead in the wet locker which is right next to the cabinet I've mounted the stereo in.

What I'm wondering is, will the thicker & stiffer wire of the car antenna receive signals any better than the flexible wire I currently have? If not, then I may be better off just extending my wire and doing a better job of mounting it so that it's extended and not curved anywhere.
 
#7 ·
Now that's a creative idea! I think to maximize reception the goal is be at 1/2 or 1/4 wavelength as measured from the center of the FM band. That works out to about 31-33 inches from what I've been able to read. I wonder if you're close to that between the wire and stanchion.
 
#6 ·
Mine is a piece of coax antenna extension wire, about 6 feet long and the stripped core attached to a shroud chainplate fitting inside a cabinet. Works great.
 
#9 ·
This is a sailboat right? You've got to have a metal guy wire somewhere? The higher the better. get a piece of coax. You will get the best reception with height, and an even multiple of 1/4 wave. The spacing between the wires in a coax or twin pair lead is the impedance. In an antenna you are converting from infinite impedance to usually either 75 or 50 ohms. that is what the antenna is for. The easiest way to do this, (barring the desire to to a lot of calculations), is to connect the shield to ground, and slowely move the inner conductor along the spreader, or whatever you are using until you get the best signal, permanently connect it to this point, job done.
 
#10 ·
Certainly is a sailboat, and it certainly has wire rope standing rigging. Maybe one of the shrouds is close to a 1/4 wave multiple? The catch is, I have a deck-stepped mast and I really, really, really do not want to create another deck piercing for an AM/FM antenna.

I can get good reception below decks with a cheaper portable radio using its built-in telescoping antenna, so I know that I don't need to go all the way to the spreaders to meet my needs (although it may well do a much better job up there!).

The goal here is to figure out the best options for hiding antenna somewhere within the cabin and improve upon the reception my cheapo wire is capable of.
 
#12 ·
"What I'm wondering is, will the thicker & stiffer wire of the car antenna receive signals any better than the flexible wire I currently have? "
Not really. In theory a wider antenna conductor (the antenna itself) has a wider frequency range but that shouldn't even be measureable in this case much less significant. The only difference would be that a car antenna will be serviced by a shielded coaxial cable, so the length of the actual "live" antenna is tuned to match the radio service, and the coaxial shield blokcs the rest of the wire run. If you've just using one long piece of wire, the length of the entire wire is being used as the active antenna. Which might actually be better--or worse, no real way to tell except by experimenting, because you don't know what other interference, etc. will be impacting it.

Junkyard, car antenna, I'd gamble $5 on it.
 
#13 ·
Junkyard, car antenna, I'd gamble $5 on it.
That is what works for me on my boat. I keep it upright with some zip ties in a hanging locker - right next to the AM/FM Radio.
 
#14 ·
Get some coax from an old antenna that has the right end for your radio. Cut the jacket off for about two-three feet from the end to expose the braid, separate the braid near the jacket enough to pull the inner conductor out. When mounting, pin the inner conductor to one side, and the braid at the other, with the feed in center. If you mount it inside a cabinet so each half goes on two sides of the cabinet, (inner up top, outer closer to bottom) it will be pretty much non-directional. The higher you can mount it the better it will receive.

Can do similar with regular TV style twin lead, in which case, make a T from two pieces, strip back the ends of one for the Top of the T and twist them together, then cut one conductor in the center of the , strip both sides of the cut one back, then strip and attach the feed to those. You'll end up with one conductor outlining the T, feed the radio from the bottom of the T.

A single lead will work, as in connecting to the mast or shroud, but you'll get better reception if the antenna circuit is balanced, actually seems to work better in many cases with more ground than radiator.
 
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