Just starting out in Part 15..

[928GTS]

Just starting out in Part 15..

Hello there! While browsing around on my various shortwave and general radio review sites I ran across something about Part 15 broadcasting and it fascinated me. I mean,gee,imagine broadcasting to around a mile with no license whatsoever.
Either way seeing how this has piqued my interest i’ve decided to give it a go. Now I,like a lot of people have in the past,have my sights set on an SSTran and,after doing a few odd end jobs,should have enough cash to obtain it.

Now my situation is that I plan to broadcast from my house and i’d probably have the transmitter inside located right next to a window. Now this will be either on the second floor(some 30ft up)or the third floor(some ~50ft up)depending on what I can find out here. Now my goal is to broadcast a mile. I live in a relatively poor soil conductivity area with a rating of around 4 according to the map. The deal is that I really don’t have the money at the moment or in the near future to either afford one of the prebuilt antennas that the SSTran site refers to nor do I really have the means to build one which means the radial ground system is out of the question seeing how that has to actually be connected to the copper pipe itself on those types of antennas,right? So what I was wondering is whats the best ground system for my situation? Outside of my window and directly below me is a row of dirt so I could always set up multiple stakes..

Another question would be what would be the most efficient way to setup the wire antenna? I could:
-Hook it up to the mesh screen of my window
-Run it out of a window and tie it to the deck railing that is right outside of my window
Now I managed to find this antenna(http://www.kenneke.com/~jon/amantenna.JPG) in my searches and I was wondering if this would be able to push me out to my goal of one mile?

My final question is that for my general receiver antenna I have this rather large antenna that measures some 110ft and covers atleast half of one side of my house and I was wondering how well would something like that broadcast and is the FCC actually capable of zeroing on a signal and saying something to the effect of “Oh this signal is far too strong,he must be using an illegal antenna of some sort!”?
So yeah would it be that much of a faux pas to at night,just for giggles,plug the SSTran into that and really shoot the signal out there? Naturally i’d operate up in the frequency range to not piss anyone off and where I live all the action is from 980-1180 and after that it’s pretty much dead save for 2-3 stations.

Edit:Also would something like this(http://www.quasarelectronics.com/1038.htm)help boost my ability to broadcast or is this just for a receiver and not a transmitter?

So yeah just another 17 year old radio geek(just another..hah..:P) who wants to push some music out to his community and so any answers would be greatly appreciated.

Thanks,
-Mike

[scwis]

8)

Welcome!!!

Thanks for stopping by, and thanks for asking some excellent questions!

Here are some answers, and a whole bunch of opinions

[color=darkblue:41e2413214]”I’d probably have the transmitter inside located right next to a window”[/color:41e2413214]

Bad idea. Where you’ll want your XMTR is absolutely as close to your antenna as possible. Where that turns out to be depends on a lot of things, but number one, you want to be close to your ANT input.

[color=darkblue:41e2413214]”I live in a relatively poor soil conductivity area with a rating of around 4 according to the map”[/color:41e2413214]

4 ain’t that bad. It will definitely do fine.

[color=darkblue:41e2413214]”which means the radial ground system is out of the question”[/color:41e2413214]

Not necessarily, but more important, everybody benefits from more ground. If you live in a “30” it’s easier to connect to the ground, but more is always better, so do as much as you can, and don’t rule out anything. Ground rods, ground screen, hook it up to everything made of metal within 200 yards, what ever you can do safely.

[color=darkblue:41e2413214]”I managed to find this antenna…” [/color:41e2413214]

Probably not that much help. That’s a plug and play for a person who just needs to get to the next room in the house, not the next block. I’m sure it’s a fine product, but I’m not sure it will help you reach your goal.

[color=darkblue:41e2413214]”I was wondering how well would something like that broadcast”[/color:41e2413214]

No real way to know but to hook it up and find out, there is the reciprocity rule – see next answer, too.

“is the FCC actually capable of zeroing on a signal and saying something to the effect of ‘Oh this signal is far too strong, he must be using an illegal antenna of some sort?'”

Of course. Finding a stationary, AM BCB signal source has been easy since the 1930s. Analyzing its signal characteristics came shortly after. Doing it all with a pocket-sized, GPS enabled, XMTR fingerprinting, battery powered unit is easily possible today. Some people still do it for fun.

Some might say that the best strategy for any experimenter is to not give people a reason to look for you in the first place. That means not interfering with others’ signals, not causing interference to consumer devices and not broadcasting content that makes people want to come looking for you, whatever that might be in your community.

I think the most important thing to remember is to learn as much about the theory as you can, but to experiment with what ever you have at hand – within the bounds of personal safety.

Just try it and see what happens. I slapped together an antenna back in 1999 that really shouldn’t have worked, theoretically, but it did. It was so anti-theoretical that I cut it down and threw it away and put up a theoretically proper antenna – and have yet to regain my anti-theoretical range.

This isn’t chess. It’s great big radio waves being squeezed out of a little tiny antenna, at ridiculously low power levels. Strategy counts for very little, action brings results.

Then come back here and tell us how it went

[12vman]

Howdy folks..
I’m a newbee here and want to give everyone a big “HELLO”..

I’ve been pondering this low power a.m. thing for years and decided to build one to see what happens. I’ve already built an f.m. tramsmitter with a j-pole antenna and had some fun with that. I was covering a 20 mi. radius with .7 watts so I believe I have a great area to construct a antenna system for the a.m. band. I’m on top of a high hill about 200′ above the average elevation around here so I believe this is an advantage. If I get a “tuned” grounding system things may work out well..

I have a background in radio theroy but never messed with low frequency much. I know there is “tricks” to everything so I’ll be looking through this place a lot..

One question..
I have trees that cover the whole outside perimeter of my area that is around 50′ higher than ground level. If I build an antenna system on the ground, will the trees mess my signal up? I also have a platform that is 20′ off of the ground that has enough area to construct the antenna but the ground area will be different compaired to being on the ground. Any comments?

[frankh19]

A ground-mounted antenna will work great even at the upper portion of the AM band where most Part-15 stations operate. Height at medium-wave frequencies is not nearly as important as a good ground system. If your location has good ground conductivity, you’ll be amazed at the coverage with 100 mw.

[PhilB]

[quote:0cc5d32539=”frankh19″]Height at medium-wave frequencies is not nearly as important as a good ground system. If your location has good ground conductivity, you’ll be amazed at the coverage with 100 mw.[/quote:0cc5d32539]

I agree. There are very simple technical reasons that make a very good ground system the most effective way to increase range. Standard antenna manuals and textbooks don’t cover this well because they are geared toward amateur and professional antennas which typically are much larger relative to the operating frequency and are not as dependent on a good ground. Part 15 3-meter antennas have pathetically low radiation resistance at BC frequencies. Attention to a very good ground system with very low ground loss resistance can multiply the radiated signal dramatically.

Height is a secondary factor, but can be important when a ground level antenna is surrounded by buildings as is the case when houses closely surround the antenna on all sides.

Phil B

[12vman]

I guess my question is.. Does the ground system need to be “On the Ground” if I can get some resonance from some elevated grounding? I do have a basic understanding on the physics of antennas but never messed with this low of a frequency. If things are the same as with other frequencies, If I can get some reactance from the driven element and a tuned ground to whatever part of a wavelength, I should get some results and more elevation also. Or, is the earth ground and the conduction of the earth itself make a big factor in performance?

I totaly understand that the 3m antenna is no where near even a half wave radiator BUT if one can get a good, balanced, somewhat resonate ground, It should make a difference. I figure I could work at it from a 1/2 wave point and I understand the lengths involved. This is where variable caps, coils, and resistors come in to play. I believe I can make it as big/small as needed with some figuring and playing around.

Is 100 mw worth all of this? I understand the losses in the 3m antenna itself but I want to get all I can get with what I have. (typical radio head, huh) I did fm.. That was too easy. This appears to be a challenge..

[PhilB]

12vman,

Unfortunately there is not nearly as much solid technical information published about short antennas at low frequency as there is about more conventional antennas. I would love to see a really good technical analysis published about elevated ground planes for short antennas at low frequencies. Their effectiveness at AM frequencies seems to be more a matter of trial and error which is difficult due to the heights and lengths of wire involved.

A more conventional tuned part 15 antenna with a standard ground radial system is pretty well understood and has a simple mathematical model. As long as the antenna is elevated up to about 20 ft above ground, the model seems to apply. When a tuned antenna is elevated too far above a standard ground system, the model changes. 20 ft is a small fraction of a wavelength at AM frequencies, so the ground situation doesn’t change much. Beyond that, when the height becomes a significant fraction of a wavelength, then the model changes.

I know that some have reported success with elevated ground planes, but I have never seen any real experimental proof that they are of real benefit. For example, someone may report that their signal improved when they strung some ground wires out from the base-point of their elevated antenna, but this is not meaningful unless it can be compared against a description of the ground system in use before the elevated radials were added.

The Part 15 broadcast community is populated by a significant number of people who have little or no knowledge of antenna theory, but they are typically very enthusiastic about part 15 broadcasting. It is often difficult to sort out the lore from the facts.

It would be wonderful if there were a book written by a real professional antenna engineer focused on 3 meter AM broadcast antennas. If anyone knows of one, I would like to know about it! Otherwise we are stuck with the simple model which has its roots in mobile and portable whip antenna analysis by ameteur radio people for the 160 meter band (just above the AM band).

Phil B

[scwis]

[quote:98cf76b5af]people who have little or no knowledge of antenna theory, but they are typically very enthusiastic about part 15 broadcasting[/quote:98cf76b5af]
I’d say PhilB described me perfectly – I’ll hack at it and hack at it with only a vauge idea of what I’m doing, and when something works, I seldom know exactly why. It’s a blast 8)
[quote:98cf76b5af]Is 100 mw worth all of this?[/quote:98cf76b5af]
My answer might suprise you, but no, it’s absolutely not worth it – not worth it if your goals are range, number of listeners or other typical broadcast metrics.

You can reach far more listeners with a modestly promoted webcast, you can get far better range and fidelity going FM pirate, and you can go around the world as a SW pirate. Any of those venues are far more satisfying than Part 15 AM.

The only thing that’s interesting to me is that it can work at all. I get a real kick out of setting up an antenna and getting out a mile on 100mw (and remember, that’s power in, not RF out!). I enjoy tuning in my own radio station for a few minutes as I leave for work, and for a few minutes as I approach home. I have my clock radio set to my own station so I can wake up to my own programing. I broadcast in an apartment complex, so about 300 peole are in range of my signal. I stream a feed from an AM receiver so I can monitor my transmitter when I’m out of range. It’s like pet hamster or an R/C airplane – it’s just fun, if that’s what you’re into.

That, and the fact that it’s not against the law.
I’ve had the FCC talk to me once already, and I’d prefer to not do that again. 😥

[PhilB]

I love the quote that is always high up on the part15.us home page:

Quoteable Quote:
“This is not a hobby for the thin-skinned, that’s for damn sure!”

That says it all for community relations, dealing with the FCC, and technical issues.

Phil B

[mlr]

Must have been some grand thinker who spoke that quote.
[/quote]

[12vman]

I enjoy challange. This can become quite a project and a very indepth one also. I will add it to all of the other projects I have going on here.

I live totally off grid outside of a small town. I had an FM station going on for a while and lots of folks got a kick out of it. The power out was too high.. (.750watts) with a gain antenna.. (J-Pole) I built the transmitter from a kit and used an amp from Ramsey and it worked quite well. I shut it down because I didn’t want to get into any trouble. I covered about 15-20 miles! My location is great for radio..

This AM thing will be my next adventure. Believe me, I will get the max out of it if it takes me a year.. lol

[928GTS]

Well I got my SSTRAN transmitter and that antenna that I mentioned earlier in the mail and decided to set it up in my sunroom and strung my antenna up as high up as I could. Reception? A bit pants,I only managed about 150ft in one direction,if I went at a 45 degree angle the reception was rather iffy. I then tried it with the adjustable antenna and reception was even worse though I think it’s because that I need to repeak the RF output on my transmitter when I hook up that antenna and use it’s matching capability.

Later that night just for the hell of it I hooked it up to my 50-60ft antenna I use for DX’ing and reception tanked some more,guess they weren’t kidding when they said that it was designed for 3 meters and no more,joy. I strung the 3m of wire I got in the antenna tuner and dropped it out of my window and reception was slightly better but still not great.

The next morning I went out to my patio and setup shop by running the 3m antenna into a tree and this time setup a ground and it got quite a bit better. I could get about 110ft out if I walked in a path in which the antenna was in view and about 70ft if it was obscured. Now my ground was a mere stake driven into the ground and connected to the ground wire on the wire antenna that was supplied with my SSTRAN. I then shorted the S7 bridge on the SSTRAN(anyone who has one knows what I mean)and it seemed to work a little bit better with an increase of 20ft or so in range. Next I threw caution to the wind and scrounged up every single piece of scrap wire I had and tossed that big contraption over the highest tree limb I could find and range only increased about another 20ft although the sound quality was a bit better.

So yeah it seems like it works about as well as it’s ever going to with the 3m wire and it seems like i’m simply running out of it’s designed capabilities with a long antenna. But i’m still perplexed with my 200ft range. I know my ground and antenna is a cobjob effort at best. What i’m going to try to do next is:

-Remove all the jumpers regarding RF ground isolation and see if that helps
-Get myself a multimeter that works and repeak the transmitter and try it with and without the antenna tuner
-Try getting that 3m piece of wire out of my window on the second story and have it wrap along the side of my house seeing how my window is next to my second story porch so I can just attach the antenna there for anchorage
-Get myself a ground that doesn’t suck i.e no more wires wrapped around my radiator’s bare metal pipe heading downstairs
-Hope for a miracle

Well it’s a start and i’m not sleeping until I get atleast a mile out.

PS:Also why does it seem that my station gets “wider” across the band the more antenna wire I pile on? Don’t worry,I was getting out no more than 200ft from my house so it did no harm.

[frankh19]

This is my observation having gone down the same road with a Metzo. To get out a mile, you truely need to use a base-loaded antenna as shown on the Sstran website or the MLR antenna shown here. That, along with a proper ground, will give you the coverage you want.

When I had my Metzo, I tried everything with the 3m wire: grounding, elevation, tuning. Nothing helped until I built an antenna for it.

The cost to build is about $20-$30 for the parts, but it is labor-intensive. Most of the work is in coil-winding.

The difference in coverage with this antenna is dramatic and it’s worth the effort.

[scwis]

Here’s the links to the library pages with some antenna articles articles

[url]http://www.part15.us/modules.php?name=Content&pa=showpage&pid=9[/url]

[url]http://www.part15.us/modules.php?name=Content&pa=showpage&pid=11[/url]

Have fun! 8)

[928GTS]

Yeah I figured,I’ll probably save myself a good 240$ by not buying the premade one as I simply do not have that kind of money underneath my couch cushions. One question,do I have to do all the modifications on the SSTRAN website that require you to take out components,etc to have it work with one of those antennas as I bought mine prebuilt and I’d hate to tamper with perfection. Can I simply just use the jumper over the R14 resistor and get on with it?

Also if I built such an antenna and I wanted to mount it on my 2nd floor patio floor(trust me,no one ever goes there so it shall be no hinderance whatsoever)how would I ground it? Would I simply run a thick wire from the mast down to a few steel spikes driven down into the ground and hook it up to those spikes?

Also scwis do you have any larger pictures of the assembly process that are shown on the first page also the page cites it’s for 1700khz,i’m probably going to settle down around 1610-1630,will it still work well there?

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