Hi, this is my first posting. So hello all.
Hi, this is my first posting. So hello all.
I have an SSTRAN LPAM xmitter. I recently moved from where i had all the room I needed for the antenna, from the plans on the SSTRAN site. Unfortunately, now I'm in an apartment situation, which tossed my big antenna plans out the window. All I have now, is a room, with a window (2nd floor). I do have a large air conditioner unit that is in one window that juts out about 4 feet or so.
Has anyone found any small antenna that I could place on the ac unit, perhaps like a magnet mount antenna, like a CB car roof mag mount. It would have to be legal. My work van is directly below the window. I probably could get away with running, a power/audio line to the work van, and run the xmitter in the van, but again, I would need some sort of mobile type of antenna, like a modified CB mag mount for the roof of the van or to sit on top of the metal ac unit.
Anyone have any ideas ?
Much appreciated, Ron
Ron,
Welcome to the board!
What have you been using as an antenna? You are aware that the SSTRAN works with a 3 meter wire and you can get started with this. Just make sure you consult the manual about the switch settings, etc.
I wouldn't bother with a mobile type antenna. You might do better with some sort of coil loaded antenna inside your dwelling. Here, I use a coil loaded antenna in my basement and don't set the world afire with my signal but it does cover my property very nicely. On a truck radio I can copy it clearly out to about 2 tenths of a mile.
Try the "stock" wire antenna and let us know how it works for you.
Neil
I agree with Neil that you should start with the 3M wire antenna supplied with the kit. You can try hanging it out the window or run it up along the wall in your apartment to see what works better for you. I had an interesting experience with mine. I draped the antenna over my TV set in the living room and it covered my entire block, a distance of about 500-600 feet, with an extremely strong signal. I surmise that the antenna was radiating into the degaussing coil that sits around the picture tube, and was being coupled into the AC power line that way. Any time you move the position of the wire or change anything that is hooked up to the transmitter, please re-check the tuning.
What are your intentions as far as coverage is concerned? Are you trying to cover your own apartment, the entire building, or as far as you can get outside the building? This will determine what kind of antenna will be needed. You could potentially get a CB antenna (102" steel whip), mount it on your air conditioner, and feed it with a loading coil like the one featured on the SSTRAN web site. You could also use just a plain piece of wire dropped out the window with an external loading coil. I have to say that tuning the loading coil might be a bit difficult for a beginner, especially without any test gear. If you rely on the tuning network that is built into the transmitter, tuning is very straightforward, but efficiency is lower.
Grounding is another important factor. It will likely be impossible to find a good RF ground in your apartment, but you can try the outlet cover screw or a cold water pipe if you have one handy. Keep in mind that if the pipe is not made of metal it will not do you any good.
Good luck!
WEAK-AM
Classical Music and More!
Hi guys, I want to thank al of you for your help! Sounds like a great bunch of guys here.
Well, I guess I did leave out some info about any restrictions I have, as far as what I have been using.
I originally used a 102" cb whip, that was on the work van that I look out my window, over this 25 year old ac unit. The ac unit has come in handy, with my mag mount scanner antenna, ant 2 meter mag mount whip.
My landlord said he wouldn't mind if I dropped a copper wire to the outside garden hose, although, that would be 12', and as usual, the FCC is not very clear if that's ok. Seems like the FCC has gone metric now, lol. Oh, and I’m confuse about loading coils. A coil when wound is maybe 4". Unwound a few feet, is a coil measured in its "wound" state or "unwound" state (stop laughing, lol). From my basic antenna knowledge, a whip, as the radiator, and a ground as the other half, sounds to me like a vertical dipole.
On 2 meters, I used to make up a quick handy talkie traveling antenna, with 2 pieces of metal coat hanger. 19" up and 19" down soldered to the "back" of an so-239 chassis mount connector, bottom 19" to the one of the chassis mounting holes, and the other 19" section to the SO-239 center solder tip. This left me with a nice SO-239 connector to attach my 2 meter ht to with a short RG-58U jumper, male PL-259 to BNC connector for the ht. It was cheap, simple, and I even had the hook part of a plastic coat hanger epoxied to the other half to hang it to whatever I could find to hang it to.
I'm no brain surgeon, but I’ve never liked using a rubber ducky antenna to cook my brains as I was talking. Sorry... I got way off topic, but, this brings me back to my sstran dilemma. I'm an old time ham. We used inches. 19" was a 1/4 wavelength at 2 meters. I worked in radio (am), and the antennas were all well over 100'.
Ok. I'll cut it short. I would be allowed to use a 102" whip either on top of ac unit. Or use the one on my van below my window, power it from the truck, and send the audio down with some shielded Belden wire. Or find a legal fm transmitter, or as the FCC now calls, "intentional radiators" ?????, to send down audio to the van.
I'm not sure, what all the rules of the board are yet. I apologize, in advance, if I’ve broken ant rules.
I'm a big boy now, tell me if I’m off base.
P.S. I want to mention one more thing. I needed some parts for my sstran, and paul from sstran went out of his way to make sure I got what I needed very quickly. He's a great guy.
Ron
Ron,
I am going to address only a few points you raised in your post and maybe others will jump aboard with their comments.
The length of the wound coil is what is counted toward the antenna length limit. We had a long discussion about this on this board a year to two back and it was generally agreed that since the FCC rules do not specify the coil length that it is reasonable to count the physical length of the wound coil as part of the total length toward the 3 meter limit. This is not an FCC statement about this but rather an interpretation which many of us believe is defensible.
For your reference, 3 meters is just a few inches short of 10 feet. Remember this limit includes the antenna, ground, and transmission line. You mentioned board rules and so far so good with your posts but, in case the question comes to you, the interpretation of ground leads has been extensively discussed here and we prefer to refer readers to the SEARCH function to find the posts regarding ground leads rather than rehash this topic.
Dittos on your comment about "Paul" at SSTRAN. I believe he was probably Phil and he has been very helpful to me via email when I had questions about the SSTRAN.
Neil
I know that this topic has been covered previously, but I'll jump in with my 2 cents worth. It used to be that certain people were of the opinion that you had to count the actual length of the wire in the coil as part of the 3M limit. Of course, that would make the use of a coil completely impractical for Part 15 AM. More recently I believe the accepted practice has been to go by the physical length of the wound coil, as stated in the previous post.
In case anyone were to ever complain about it, there are two work-arounds. The first is to use a toroid. If you choose the proper iron mix core material, you can make a small toroidal coil that is quite efficient. Maybe not as efficient as a large air wound coil, but very good nonetheless. Or you can do what I did in my own transmitter design, and that is to incorporate the coil inside a shielded transmitter enclosure (along with any other antenna tuning/matching components) such that the coil produces no radiation. If you maintain adequate spacing between the coil and the enclosure, it will not significantly degrade the Q. With the coil inside a shielded box, it would be hard for anyone to argue that any aspect of it should be considered in the antenna/ground limit. I found that this arrangement worked very well for me.
WEAK-AM
Classical Music and More!
Ron,
I read this forum frequently, but don't always have time to post things.
The AMT3000 requires a base loaded antenna for serious range. The internal tuning circuit is fine for in-home use, but the tiny inductors on the board limit range. The base loaded antenna moves the tuning inductance out to the big 3" base coil which is many times more efficient. Also, antenna capacitance is fine tuned by adjusting the length of the antenna. See the plans and tuning instructions at: http://www.sstran.com/pages/sstran_buildant.html
In your special case, you have been approved to use a 102" whip antenna. The trouble with a CB whip is that there is no length adjustment. MFJ sells a real nice 10 ft telescoping whip. See: http://www.mfjenterprises.com/Product.php?productid=MFJ-1954
This whip has a standard threaded 3/8 x 24 stub at the bottom. You can buy a matching threaded mount that could be installed in the center of the top PVC cap of the loading coil. The telescoping feature will allow length adjustment for fine tuning.
You could mount the coil and antenna on a base plate with a pipe flange and then clamp the base plate somehow to the air conditioner.
I don't normally recommend the MFJ whip for outdoor use because it isn't strong enough to withstand high winds, but in your case, it will be somewhat sheltered from wind by the building. If it does ever break due to a freak storm, just get another one for $29.95 (cheap).
PhilB
how about a 4ft or 2ft fire stick for CB? it's basicly a helically wound 1/4 wave at 27mhz which is the equivilent of a 102 inch whip.
it obviously won't work as well as a full 3m whip but it will do what you want.
Thank You,
Rev. Robert P. Chrysafis
Universal Life Ministries
http://www.ulc.org
Moderator Hunterdonfree
http://groups.yahoo.com/group/hunterdonfree
If you want to extend your range some, try this. When I was using my SSTRAN I had an idea of grounding both wires. I Hooked my Ground wire to the screw on my lightswitch, and I ran my antenna wire to a ground stake outside. The Telephone Network Interface was grounded to that same stake. I had range of about 50' away from my house daytime, but at night It couldn't be heard right outside. BUT, Around the powerlines my signal was crystal clear, even at night. I had a range of about 4/10's mile of strong signal. After that there was a transformer, and I virtually got nowhere past that.
You may have good results, if not, just experiment 😉
Travis