Need help getting reception with am radio

[dmurdock]

I'm a 'puter geek who works in the middle of a large cement building surrounded by miles of electrical and network cable, and behind me it's floor to ceiling servers, the rest of the room is surronded by glass. Now the problem is, I would like to be able to listen to my favorite am sports station, but I can't pick them up. I know nothing about am antenna's, but would a long wire (used as an antenna) help or does length not matter, just location. Just looking for any tips...



ps-If it would help, I can tap into a network cable (unnatached to anything on the other end) and give myself a good 20-30' of antenna, i just don't know if this will help.





thanks-dm

 

[Todd G]

You can forget about AM in that environment. All a longer antenna would do is pick up more noise. Maybe an external antenna ouside of the room would help or one of those contraptions that converted the electrical wires into a big antenna. I know what you mean about server rooms. Not even my cell phone will work in the dungeon where I am sentenced

 

[MJawsman]

From what I understand... . AM requires a really (!) long antenna to work. The round or square things you get when you buy a new stereo are essentially a lot of wire wrapped up. Maybe try hooking a spool of wire up and see what happens? I'm sure there are EE's out here who could tell you more of what you'll need or how to get it done right. Just my $. 02.



Mark

 

[dmurdock]

Yes, i'm waiting for one of those guys who builds his own radios to post (there has to be at least 1 on this board, we've got one of everything else )

 

[nickleinonen]

does your office get cable tv? here at lease where i live, i can pick up many am radio stations that are being brodcast on fm channels when you hook up a radio tuner to the tv cable. . it might be avalable in your area, and it might work. . worth a shot. .



or see if that station has a net brodcast. you could log on to their site and fire up the pc sound card and speakers and listen that way

 

[WTBurke]

Hey DM

You have a tall request, however; you could do a half wave dipole but the length will be very scary. The frequency to wave-length can be calculated by ... 468/f. Example if your favorite station is at 1000 on the radio dial then 468 divided by 1 = 468 feet. ( 1000 is 1meg on the am dial) This gives you one leg @234' and the other @234'.

_________________ _________________

234' 234'



The center is the "feed"point where you would connect some 75 ohm TV type coax that drops to your receiver. Positive to one leg shield to the other leg. The inductive and capacitive reactance of this sort of antenna for a single frequency should be of little concern to your receiver. I know this is "nuts" to do in an office building... suspending a contraption of this size gets scary but it would work very well if you can get it into the clear.

Your present receiver has a "ferrite rod" antenna built into it. It is a large amount of very fine wire wound onto a solid "ferrite" rod. This is a large "lumped-inductance" type antenna that is very "directional" and very ineffciant... . but it works... . sort of. The "long-wire" has extream "reactance" at many different frequencies and would require an "L-network" to tune out the reactance at the desired frequience of intrest. Also a good ground is a must when using a long-wire. A good ground is way beyond a wire to a simple cold water pipe.

The ARRL.org is a great web site that could help you research a "space-saver" type antenna that would be of the "monster type" lumped-indutance rod that can be built for less than twenty dollars but, would work so much better than what you have at this time.



Sorry for the long answer... . I'm a "radio-nerd".

William

 

[radar doctor]

WT BURKE ( Good ADVICE)

Hi DM I concur with Mr Burke. I do AM late at night and have worked for the Govt in this Field for 38 years . Its good to see some Techs on the TDR

 

[dmurdock]

I have reception!

Mr Burke, I think i did something "kinda like" what you are describing. I removed a panel in the false ceiling, then connected a spool of twisted pair to a "cable shooter" (basically a "gun" that shoots a weight with a string tied to it so you can pull network cable long distances), shot the wire across the ceiling (i think it went nearly 40'), then fished it down the wall and wired it to the antenna of the radio. This, along with changing the frequency on some nearby monitors, and plugging the radio into a power conditioner worked. I still have a slight amount of hiss, but when i'm doing anything intense (like programming,etc. . ) I always wear earphones, and the earphones don't carry the hiss like the speaker does. I think the wire accounted for about 50%, changing the monitor frequencies about 40%, and the clean power another 10%... overall, i'm a happy camper. Thanks!