Welcome me to Part15.us! I’ve been checking in for about a year after returning to LPAM Part 15, having been one of those with Allied & Knight kits in the ’50s. Now a webcaster, an AM signal in the house is perfect for monitoring the days programs. But I found that a 3-meter indoor antenna had very poor coverage outdoors, where I spend time gardening. Building an outdoor rig is a large construction project and it’s something for next year. In the meantime I found a solution which I’ll share.
I placed our SSTran3000 on a cut-to-size laminated board under the edge of my desk at a front window, ran 2.5ft. antenna wire up to and underneath the window, attached it to bottom of the aluminum storm-window frame with a self-tapping screw. The vertical size of the window frame is about 5ft. Outside on the front porch I used an existing screw at the top of the window, cleaned and treated with “DeoxIt,” and added 2.5ft. wire up to underside of porch-roof and secured it in an available crack where I wedged the tip of the wire.
Result: Strong coverage (1640KHz) everywhere inside the house, outdoors all the way to the street (100ft.), and here’s a magical part: the signal is equally strong in the backyard all the way to the mulch-pile (100+ft.). There must be a “skin-effect” where the signal wraps around the surface of the house (I made up that term). It seems the signal goes into phase with the front wall inside and out because reflection is not possible since antenna is part of the wall.
What could go wrong?
Your Novel AM Antenna
Welcome to the board! I also started out with the KnightKit AM broadcaster kit and have many stories about hum and electrical shocks from this unit. Nonetheless, it was a lot of fun. I still have my unit and it still works, even with the old selenium rectifier, though I had to replace the filter cap.
Thanks for sharing your antenna “design”. As you probably know part 15 AMers don’t have the flexibility of design that others such as hams or licensed operators enjoy. If one operates under 15.219 then one has to be aware of the antenna length restrictions. If one operates under 15.209 then it is a matter of field strength.
From what you describe, you are probably OK under part 15.209 but the problem is that most of us have no realistic way to verify this. Enjoy your transmitter and keep a low profile and thanks again for sharing your adventure with us. Post often here.
Neil
Windowframe Antenna
Thank you Neil for your comments. Yes, the question of meeting FCC Part 15 requirements is very much in mind. The antenna I described comes vertically to 3-meters (10 ft. being a few inches more), but the window frame of course has width. But the Part 15 rules don’t mention width. Other antenna designs get into pipe thickness, but it’s not discussed as an FCC issue, but usually as to whether added diameter improves modulation by enlarging bandwidth, but of course there are specific bandwidth limits in the FCC rules. Returning to my windowframe antenna, I have no ground since all the length got used up by the antenna. The transmitter is right inside the front door so that an FCC visit (please never) would at least be convenient. Actually, the transmitter could be put out on the porch, which would move the first 2.5ft of length from inside to outside.
Love those serendipitous antenna designs!
I’ve had a few lucky breaks in that area myself. You might have an inadvertent center loading coil of one half turn, or more likely, you’ve created a one turn loop, both of which would seem to be OK under the rules we try to follow. The outcomes you’ve experienced definitely sound like a loop.
Just to put your mind at ease, I’ve had the pleasure of an FCC contact and my experience was pretty low key.
It seemed to me that as long as there aren’t ridiculous power levels, egregious antenna or ground violations (as in 50 feet of either) or seditious content, it would be a fairly straightforward experience. Turn it off, fix the part that’s out of compliance and have fun.
If you’ve ever looked at the link to FCC field notices you’ll see that the only folks who get roughed up are those who sell non-compliant equipment or those who ignore repeated FCC notices.
http://www.fcc.gov/eb/FieldNotices
Those of us involved in good faith experimentation seem to be treated as such.
Welcome!
My first am transmitters started as a radio shack 35-in-1 and later a 1950’s? model Heathkit 35-in-1. They both had the springs where you wired the kits. I think i had the best coverage with my Heathkit wired to a old buick car antenna (the telescopic kind) and the ground was the tin flashing on the roof outside my window. I got out at about 1/4 mile with fresh D batteries.
Again welcome!
Low Profile
Thank you scwis for peace of mind on possibly being tazzed or put on a chain gang for tinkering with mini-radio. And Neil spoke of low profile. I was just now thinking of all that, and decided to use the windowframe antenna only while outdoors, as my setup is expressly intended for self-listening, not reaching the neighborhood. But those who want to serve the community are important too, as I strongly believe some middle ground ought to exist for operating small stations. The large stations don’t want competition, but most of the audience have abandoned them because they don’t program what people want. At least Part 15 allows individuals to program their own.
Welcome Aboard!
Your window antenna reminds me of the bed springs I loaded up as a 10 year old.
I started my Part 15 experience in 1962 with a Remco Caravelle, a combo AM receiver and transmitter. From there a Lafayette KT-195 tube broadcaster kit. Then I got a nifty book at the library and built a 1 transistor broadcaster, best signal yet!
Nearly 50 years later I’m still playing at it. I’ve been recovering my youth on Ebay buying 3 Caravelles, a KT-195, a Tiny Tim crystal radio and a few Cub Scout crystal radios all from my childhood. I’ve picked up a few newer items like the Wild Planet Radio DJ, Talking House and a couple others to tinker with.
It’s a great hobby so keep on havin’ fun.
Old Microtransmitters
scwis your references to “center loading coil of 1/2 turn” and “loop” have my imagination comparing to points of reference familiar to me. An aluminum window frame definitely resembles a ground loop, and AM loop antennas are found in many radios although I’ve yet to read about loop-antennas for transmission, although why not? I just spent an hour reading FCC Field Notices, thanks for the link, and it was highly educational. Only once in 40-years in radio did I have a drop-by by an FCC guy, and he actually killed time looking at other stuff while I wrote down all the transmitter readings I hadn’t taken.
Hello to rock95seven and mram1500.
I had no idea there were so many old types of small xmitters. I found a file folder with schematics for Knight Models 83 S760, 83 S073 and 83 Y706. It was the 760 which I used to try to get to Patricia’s house, 5-houses down the block, and it never reached that far, but she didn’t mind my stopping by to test it. Wonder if the same thing would work now with the lady down the street?
LPB made a Part 15 unit until recently, but I never see mention of it. Over.
Lost in a Fog… er, Blog
I think I understand the difference between a forum and a blog, so I’ve futured my way back to those blog days when I wasn’t sure.
This may become totally lost among the digital landslide, but I am an earthquake.
No attention was brought to it at the time, but I walked away from my several radio programs because I was tired of talking and never listening. But then I expired. Wait, no… then I was inspired… I heard new people, upstarts, newcomers, johnny-come-latelys who were appearing all over the place with part 15 transmitters and it sparked my return to the fray, frayed though I may be.
In Blare OnAir Lite No. 332 titled “Personnel Trouble” I deal with Buster Boatrocker, barber and radio commentator who became agitated at the arrival of Atrainradio’s “Rant,” and you might be impressed by how well it could have been handled.
http://kdxradio.com/archive_files/150507_blarelite332_64_V1.mp3
After that I was respirated… that is, inspired again, and decided to have you by, that is, invite you over, to hear my tale about how I made a 3D printer using nothing but a 3D printer.
http://kdxradio.com/archive_files/150509_blare_64_V1.mp3
Are you mentioned in any of these programs? Frankly, some of you are.