Spring is Coming!..Time to Get your Part 15 AM Ready To Build!

[carlvenorden]

There seems to be a renewed interest in Part 15 am radio in 2007!.......and that is a great thing.
Don't forget, we are still offering the sstran, which features the compression and level dials on the front of the box, and this transmitter doesn't overmodulate!. It has a very full, loud sound, because it has it's own built in processor!!
I"m still building the antenna for it, and this year the price hasn't gone up "yet"
Copper went up in price in 2006, so soon, the price will "probably" go up.
The price is still $350.00, shipped to your house in the Continental US.
And, it comes with a ground system too. I do expect the costs of materials to ultimately boost the price very soon.

If you plan to purchase the sstran, email Phil at www.sstran.com, and if you want the antenna to improve your range to small station status, email me at [email protected].
Right now, the system costs about $600 total, which is excellent.........to which you will have to add some copper and whatever audio leads you need to your antenna location.

It's a great system, so if you are planning a part 15 radio station now, now is the time to order the tx and the antenna to get it all in time for spring installation!

Happy broadcasting,
Carl
Antenna Guy

 

[Neil E.]

Hi Carl,

Thanks for the update.

In case you missed it, there is a thread on another board where I and another poster (MOJOE) have taken your ideas about this antenna and made a few mechanical modifications. I hope you and others find it interesting.

Link:

http://www.part15.us/node/1178

Neil

 

[carlvenorden]

Re: Spring is Coming!..Time to Get your Part 15 AM Ready To Build!..Neil

Hey Neil!
I looked at that antenna structure this morning before reading your post.
You should have tried to test that before you posted it.
That won't work, unfortunately.

From the picture I can see a couple of errors, but sinking pvc into the soil and surrounding it with radials won't help this coil/antenna at all.

I'll be honest: the original design for this antenna came from Phil at sstran. All I did was modify it to be more like an actual AM antenna (boosting it doesn't help it, adding a ground system did...etc).

When you wind the coil, it needs to be magnetic wire, not anything else, and it is now very expensive; about $110/10 lbs of wire!.......found that out last night per my wire supplier. When I started building coils this wire was about $60 bucks per 10 pounds, so my costs there have neary doubled.
Funny story: first time I tried a coil, I spent about 35 bucks for what amounted to the wrong size of wire, and there was not enough of it!..........I blew away hundreds of dollars trying to get the experience of winding the perfect part 15 coil. You can view a couple of them on my website; http://antenna18431.tripod.com/antenna.htm

The coil I make is made very similar to a real AM antenna coil/ATU assembly. If you have ever worked at an AM DA, you would see what this looks like. It's not easy to build, as you have found out.......yep, the caps are easy to do. I have made and sold a number of in line coils/antennas, they went over really well. I'd build another if someone asked me to, but the price is more. As of today, after researching the prices of materials, the cost of the basic sstran antenna has gone up from $200 ( a few years ago, and there is a reason why I mention this) to $400 today, shipping included.
Copper took a huge hit in the metals markets; I got an email from a potential customer who apparently sent me a check a couple days ago for an antenna (never knew it was coming.....it is still not here).......but he got the information off of part 15.com, and his information is over two years old; he never updated his website.

Being Steve linked my website I am not faulting him, but this potential customer took information off his website, took it upon himself to send a check to a wrong address, and at the wrong amount. Now, I have to restamp that envelope and send it back, with no sale.
That is why I don't generally link to websites about part 15 am broadcasting: as interested as these guys are, they don't keep up with current information.

Your antenna, a version of mine is not right, because basically you are depending on pvc to conduct wattage.......I'm putting it simple. Designing a pretty antenna, and mine is pretty, is simple and to build it is really work......but, ....the reason for the mast pipe is explained in my website. You will get no ground whatsoever in your design.......and you can't sink your antenna inside a piece of pvc either.............I see really no comparison between your version of my antenna.........and if you want to compete, you can have the market......and my antenna which is very workable.

Lastly, I get a kick out of emails from people who ask for me to tune their AM antenna.
A DA type antenna with a coil can not be tuned except on site. It couldn't even be done since the postal services don't deliver packages longer than 8 feet; so why do people ask for this service, if it is not offered, and apparently can not be done?

I have no problem with constant questions from customers; what I find funny is that people write saying they know all about AM transmitting systems, yet obviously they don't.
RFry can give you all the boring details as to why part 15 is illegal.........and it would be cool if he could cruise the streets looking for all these illegal AM antennas, and he should, and submit a report on what he has found......but it is a tremendous waste of time, It is what it is; and our system was tested and looked at by the FCC 3 years ago; case closed on that one. You can basically buy a rangemaster for $2K, or our system for less than $1K.
That is about it.

Really there isn't anything to say except: buy the system you like, use it legally and enjoy it.

 

[rfry]

RFry can give you all the boring details as to why part 15 is illegal....

Nothing I have posted has stated that Part 15 AM/FM are illegal. Obviously they are not, as the FCC has authorized both of them, as long as their physics are understood and accurately applied -- which explains the purpose of my posts.

You and anyone else are free to make your own choices, but should not one of those alternatives be based on the reality of what physics proves about such systems?

//

 

[Neil E.]

Hi Carl,

I recall from previous conversations with you your advice about not changing the SSTRAN design and I put a statement in the first part of the post about this. True, the coil I wound is not tested and I also disclosed that. I just did it that way because I had the wire in stock and thought it was worth a try. Unfortunately, my attention has been directed elsewhere since I wound it and that is why I haven't installed or tested it.

The focus of my post was the mechanical assembly which could provide an alternative to yours. It was my hope that someone would take the idea and try it. Mojoe did and so far his results appear acceptable, though we apparently don't have a way to compare performance to that of your antenna.

Regarding the use of PVC in the ground, I don't see why it would not work if the tx. was grounded to a copper wire ring from which the radials extend and also to a ground stake at the base of the antenna. Perhaps you have tried this without success, and an experiment would prove me wrong.

You have no competition from me since I cannot claim this antenna works and even if it did I am not interested in any marketing ventures.

Thanks for your comments and for what you have done to advance the AM hobby.

Neil

 

[Tom Wells]

I may not quite understand the PVC question, but I do know that PVC makes a lossy coil form, and if that is the only objection, it may be dismissed, with the understanding that there is not much power to be lost in a pt 15 AM.

If effiencies are good throughout the rest of the antenna system, there is little net loss.
A truly low resistance ground plane is worth far more than the losses in a PVC coil form.
But efficiencies add up (multiply, actually), or not. So a better coil form material would be worth some radiation increase.

 

[Black_Shire]

I may not quite understand the PVC question, but I do know that PVC makes a lossy coil form, and if that is the only objection, it may be dismissed, with the understanding that there is not much power to be lost in a pt 15 AM.

If effiencies are good throughout the rest of the antenna system, there is little net loss.
A truly low resistance ground plane is worth far more than the losses in a PVC coil form.
But efficiencies add up (multiply, actually), or not. So a better coil form material would be worth some radiation increase.

PVC pipe is reasonably good for Medium Wave and Long Wave frequency coil forms as long as you stick with the white Schedule 40 PVC pipe or (not much worse) gray PVC pipe. TalkingSign used gray 1" diameter PVC pipe for the coil form in their outdoor ATU, and the transmitter itself uses this for the tank circuit inductor coil form as well. Black PVC pipe is the most lossy.


-- Black Shire

 

[Neil E.]

I may not quite understand the PVC question, but I do know that PVC makes a lossy coil form, and if that is the only objection, it may be dismissed, with the understanding that there is not much power to be lost in a pt 15 AM.

Tom,

Both antenna coils use the same PVC form, coated per Carl's recommendation, with outdoor spar varnish. Carl's comments address my use of PVC into the ground instead of his use of a metal pipe so I believe that is the PVC in question rather than the coil form.

Though not detailed in the linked post, my intent was to use a radial system with a center metal ground rod all connected together at the antenna mounting base to the tx. ground. As Carl points out, my modification has not been tested, but I believe it will be electrically equivalent to the metal post in the ground with radials as in his antenna. This substitution is my attempt to reduce the cost.

Neil

 

[carlvenorden]

Finally we are having a meaninful discussion about how part 15am works, rather than how the law works.
My antenna was designed, and changed to adapt to the way it needs to be to put out a good signal, but at the same time staying lawful.

I'll address a couple comments made in the thread.
1. at 100mW........just a portion of that makes it to the antenna. The antenna itself is as effiecient as something a strong percentage short can be. Therefore, very little power goes into an antenna that is not good enough to begin with to transmit a nice signal. We have to work around that problem to provide as good a signal as possible.
2. For those that don't know what a radio station coil looks like, make an appointment at your local AM and ask to see what it looks like. For part 15, you couldn't use one of these, let alone use a tower taller than 10 feet. Therefore, our coils and antennas are scaled down versions of the real thing, in order to provide a reasonable signal with a transmitter rated 1/10th of a watt.
3. In the "real world"......a pvc base, as an insulator would be a good start, but that certainly can't hold up a tower, and that is why cement is used. Here; we need a base of iron or copper to counterpoise (that is, share, the signal between air signal and ground signal). It is generally accepted to use ground rods. However, in my opinion, ground rods work great as a ground, but do very little to send out signal.......that is why I use radials, connected to a metal base, which is connected to a ground to the tx........and that makes it legal.........and........it works.

I won't lie!.........I experimented with all kinds of coils, using cardboard, and even wood.......and with coils using all kinds of laying around type wire......what you really need to wind a coil that works is AWG magnetic wire, which in a way duplicates in a scaled down way a basic AM copper pipe-type coil. and for that coil to work, the wire needs to be very very closely wound.......like the groves on a LP. All your connections need to be as short as you can make them....every inch of additional wire adds to signal loss at this power and antenna length.

It is as simple as that. And it is all lawful. Take my advice; lets keep it simple and to the point; because exagggggggggggerating everything puts people off on part 15am broadcasting. It can be done; it isn't all together cheap, but compared to FM part 15....you can potentially put out a great signal providing you install your antenna properly and you have good soil conductivity;.........and on FM you are limited to basically feet on your signal contour.

I'm building a couple more sstran type antennas right now..........if you are interested in one and wish to purchase a sstran tx, write [email protected].
When the supplies run out..............that is going to be the end of it.
The sstran and my antenna comes in at way less than $1000. $600 is a better figure given the increase in shipping and copper prices. The next step is the registered tx, which uses a standard CB antenna .........and that costs about $2,000.

I want part 15am radio to grow, not because I build antennas for it (frankly I'm getting tired of doing this), but because I believe it to be the future of AM broadcasting as AM is as we speak. The commerical stations will gravitate all to the FM band (as Canada is doing today) leaving a very blank AM band........and 200 million radios out there that can still hear it.
Are we all on the same page now?
Carl

 

[Neil E.]

Carl,

Thanks for the coil winding advice. I really don't know why other types of wire than you specify didn't work but I will accept your word based on your experience.

As an aside, the tripling of copper prices on the commodity market to $2.85 per pound doesn't justify the huge increase in cost for a pound of magnet wire that I have seen. This must be a real headache for manufacturers.

Neil