View Full Version : Poor AM1 transmission
11-18-2004, 12:37 AM
I am trying to get an AM1 kit to transmit more than 50 feet (at 870 MHz) so a class of 3rd graders can use the transmitter to broadcast to their entire school. I have wrapped 150 ft (1/8 wavelength)of 22 guage copper wire around a wax paper spool and attatched a wip antenna for a total length of 10 ft as indicated in the AM1 instruction book. I tried ground but this did not improve the transmission. I would like to reach at least 200ft with the transmitter. Any inexpensive suggestions for achieving this?
11-18-2004, 09:07 AM
Why don't you try the Marconi Theory,
I had recently watch a PBS documentary video on “Marconi = Whisper In The Air” an inventor who invented radio. As I was watching this video, I had gotten the Idea of how Marconi had invented his first AM radio antenna tower. So I just imagined to my self of what if I tried to build something like that, but just for the Ramsey AM transmitters AM-1 and AM-25. I tried to build the Ramsey version of an AM antenna,
But it did not work at all! So then when I went to work the next morning I took my AM transmitter with me, because I worked in the back storage room where there was metal shelving. I took a piece of wire and I hooked one end to my AM-25 transmitter and took the other end of the wire; attach it to one of the metal shelving, also did a field test with a pocket radio and B I N G O!!! I achieved at lease 100 feet or more. But there were lots of obstruction in the way of course; due to the building that I was in had lots of electrical interferences and lots steel frame beams.
My plans were to build a miniature antenna tower, (10 feet high or so) made out of an Erector set like or use some other type of a metal frame such as a rod or a pole; by jointing a bunch of them together with using nuts and bolts. It would be a miniature version of an actual full size 100 feet radio tower just enough to cover two blocks or so.
I have not yet to begin to build it yet, because I been working a lot of hours at my job, and also I need to cleanup my garden apartment, so that I can find a good place to put my radio antenna tower.
If anyone or any of you Ramsey kit builders had thought of this achievement or had attempted to build one in the past, please! Let me know of your outcome of this wondrous experiment. If so, had you build one before? How far did you get? What was your theory to achieve range?
I’m going to build one from scratch and see what I can get! Please wish me luck on the wild experiment…
That's what I'm working on for my AM transmitting experiment if you get the picture???
Thank you very much
[ November 18, 2004, 01:14 PM: Message edited by: GrampaSquirrel ]
Ramsey Tech Z99
11-19-2004, 09:00 AM
Sorry you are having trouble with your transmission range. Try the loading coil on the following link: http://www.techlib.com/electronics/antennas.html . It has 10 different taps for different frequencies. If you continue to have trouble please contact me using the information below.
Patrick M. Tkaczow
Ramsey Technical Support
12-28-2004, 11:16 AM
an even better design here....
I recommend looking around this website. lots of good info in the library and part 15 resources sections.
01-01-2005, 04:30 PM
I'm wondering, as I may want to play around with AM in the future, is it possible to broadcast AM using for example the installed AM antenna inside a SuperRadio or other good AM receiver? I mean actually removing the coil antenna from inside the radio and putting it up high? I reckon that maybe an additional comopnent would be needed to fine tune the antenna to the transmit freq? What about a good AM car radio, do they also have coil antennas fed from the outside whip antenna, or do car AM radios rely on the whip antenna exclusively? I never taken a car radio apart to find out. Also, don't all AM radio recievers hace components to boost the received signal? Can this amp be used to boost before going to the Ramsey Xmitter or is that booster too weak? Sorry, I'm not a whiz at electronics, but thought maybe those that are handy putting stuff together would know if this is worth it, or just better to buy the kit and make/buy the antenna? Thanks.
09-09-2005, 12:32 PM
HElP HAS ARRIVED!!! I have a AM1 and its Constructed According to instructions.. and i use a 8 foot antenna,with a 10 turn coil added to it and grounded only to my water pipes in my basement... i get 1/4 mile range.. Audio is the key to the success, buy a small amplifier, to step up your sound, at Radio Shack they have a mini- Amplifier that has input and spkr out. and runs off 9 VOLT BATTERY.. BUY YOU A COUPLE "PHONO TO EARPHONE JACK JUMPERS..I'm sure radio shack has them too.. and boost up your audio in increments so high, but below distortion... or crank up the Cd Player you hooked to it... I added a 10 k resistor from R5 to R2/Q1 and it Amplifies your Audio and gives Q1 more drive.. since Q1 has no drive,it biases the Q5/Q6 final transistors, but this way it has Gain.. i get 1000 to 1500 feet of Range, i use the Frequency of 1350 KHZ...ALso ADD a ANtenna wire 5 feet**to the tuning coil side of C8 that gives your Tuner more POwer and Stronger OUTPUT..The AM1 AM transmitter can do 1/4 mile or 1320 feet as Advertised with my step up Mods...USE a quiet 12 volt Hobby Battery at around 4ah they sell at Radio Shack also..they look like MOtorcycle Battery or something.. Use 12 volt Batteries,,POwer Supplies Hum too much and Reduce RANGE...ADD DIODES to POWER SUPPLIES to QUIETEN THEM.. i Used 2 diodes >.> like that for + 12 volt.. remember the striped side is always the Negative Flow side(-).. so use the unstriped to hook to your +12 volt and use another diode turned backwards and hook negative(-) 12 volt to the stripe side and USE these in between your 12 volt POwer WIres to your AM1... I swear i get 1300 feet Range with a 10 turn 1 inch diameter Coil/with 8 Foot Copper pipe as Antenna...Ground Heavily as you need.. drive 4-8 ft. Rods into Earth,Water Pipes..etc. Audio may sound lil too much in your House, but when you Walk A ways like 500 feet it sounds Clear, and 1000 feet its clear, i used a Grundig Am.Fm.SW1,SW2 Reciever from Radio Shack.. Remember Am Radios haved to be Aimed At Stations to get clear Reception,, due to the Ferrite Coil at the Am recieve tuner, wherever you Aim that Reciever you pick up strongest.. i pick up Stations 1000 miles Away,,Just Aim At that State SAY " North or Northeast and i pick up Pennsylvania if i aim it South i get New orleans.. thats how Am differs from FM..Fm uses a Antenna and picks up in 360' degree angels,, Am is Directional....I hope that Helps you...2 years of Radio tech School here, i will not lie to you!!!
[ September 09, 2005, 12:57 PM: Message edited by: steve132003 ]
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