HFU HF Underground

General Category => For Sale / Wanted => Topic started by: Stretchyman on January 24, 2017, 1822 UTC

Title: MW / A.M. Tx
Post by: Stretchyman on January 24, 2017, 1822 UTC
I been messing around on Medium Wave, A.M. I think it's referred to in the U.S. and WoW it's really good on low power and put out a signal for 30 miles around with a 50' vertical and a 3W carrier, Most impressive.

The LuLu design can be used and the FET can be much better than the 510. I use a 640 and with a more volts I can achieve a 20W carrier easily.

I've decided to market this and it will be modulated with my MiNi PWM, so with 12V you will get a 2W5 carrier and 10W peak or with 24V a 10W carrier and 40W peak, more volts = more power upto 20W max carrier  (80W peak)

I've driven round listening to the signal on 1476KHz (fairly clear freq over here) and it sounds seriously good as the BASS it stonking and sounds more like the quality you get on FM!

As per I'll be selling it boxed and tested and anyone ordering on here will get a 20% discount.

The TX is tuneable over a 150KHz portion of the MW band.

Please let me know if you're interested.

Title: Re: MW / A.M. Tx?
Post by: ThaDood on January 24, 2017, 2321 UTC
Man!!!! Could have hit you up 2 years ago. Over in the USA, medium wave on Carrier-Current broadcasting is permissible license free. I was running 2W for my 610KHz station, but wanted a bit more beef. That, and my home brew and Panaxis gear was over 25 years old. So I went the way of the Greek made transmitters at       http://www.pll.gr/       when that mono 20W carrier AM unit was $500.00USD's. Not a bad buy. I was always outbid on Radio Systems and older LPB, Inc., gear, so going the Greek way seemed the neat way to go. There is a PWM AM TX out there that's 10W, but sells for around $3,500.00USD's. If you can under cut that, it would be a better way to go since the Class A TX's are power hungry. Passing thoughts. Oh, BTW, Carrier-Current is where you couple to the power lines.
Title: Re: MW / A.M. Tx
Post by: Stretchyman on January 25, 2017, 0656 UTC
Hi There DooD!

Yes it's somewhat cheaper than $3500 at $350!

How can anyone charge $3500? what's it made of... Gold?

I'm building a small remote tuner for the antenna as well so it will match a 50' wire (or longer).

Don't fancy coupling to any power lines BTW!

How popular is the 100mW M.W. thing over there?

Title: Re: MW / A.M. Tx? Why expensive in USA?
Post by: ThaDood on February 22, 2017, 1722 UTC
      Here in the United States of Amerigo Niguchi the it is very expensive to have a transmitter approved by the Federal Communications Commission (FCC). That in itself jacks up the price for transmitters that are. Even thought the Greek made TX isn't FCC approved, I am using it for Carrier-Current means and there is double the amount of harmonic suppression, so I am not worried there. The 100mW, 3 meter antenna, scene is way more popular here, and growing.  There seems to be also some innovation here to make those 3 meter long antennas as efficient as possible with loading coils, copper elements, and capacitive tophats. I am looking at doing that myself since I know that I can do better than the 2.5 meter long whip antenna that was with my Radio Systems I Am Radio transmitter that puts out a massive 92mW PEP. Oooooooooooooo, what a flame thrower. Check out     http://www.part15.us/     and        http://thealpb.com/equip-info.htm       also        http://mram.50webs.com/index_files/Page672.htm       
Title: Re: MW / A.M. Tx
Post by: Stretchyman on February 22, 2017, 1817 UTC
100mW and a 2.5m antenna doesn't sound like much fun to me and those circuits are way so old! VN88AF!

You could emitter mod a single transistor for that power but I don't see the point in 100mW except that it's legal?

With a 1 to 5W carrier you can cover most large towns and small (not too built up) cities on M.W. here in the U.K.

Folk seem to want that and that's why I designed a special low power tuneable version of my TX.