AM transmitter Antenna needed for very small space..

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jpdesroc

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Jun 13, 2014
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Hi all,
Here is the issue I'm facing about my small
home installed AM transmitter.
I use (try to use) a SSTran AMT3000 AM transmiter in my home
to be received by most of my vintage radios all around the house.
The AMT3000 original antenna is a 9 feet small wire
connected to the transmitter through an RCA type connector.
-> Even when very carefully grounded,
Very inefficient transmission no matter how you place it ..
You need to place the receiving radio close to the transmitter
and even doing so you don't get a nice clean signal
but a week one with static noise.
Here are the limitations I face and the reason for this post:
- I don't have the space in my backyard to mount
a big antenna for my transmitter
- I don't have the vertical space in my house neither for any antenna
(8 feet high ceiling)
- I need to place the final antenna -> horizontaly <- at the
ceiling of my cellar
- My cellar's ceiling dimension is 28' x 15' (usable space)

Clarifications here:
I'm not located in USA but in a rural part
of Quebec City, Canada.
and my transmitter's frequency will be 1280khz.

Here is what I'm considering as options:

- Ad a stronger transmitter like this one:
RFsource AM Power Amplifier Pallet PM62FDC
between the AMT3000 output and the final antenna (matching both to 50ohms)
I know this 60watter is overkill but ok for me.
This will permit some power loss in the process but
still have great transmitting power.
- Use a horizontaly mounted zizag type of antenna (1/4 or 1/8 wavelenght)
- Use a horizontaly mounted straight antenna (1/4 or 1/8 wavelenght)
- Grounded transmitter through house copper pipings

I need your precious expertise on what would be
the best working setup for my limitations..

Thanks
J-Pierre Desrochers
 

majoco

Member
Joined
Dec 25, 2008
Messages
3,332
Location
New Zealand
Like most of the answers on that other forum, IMHO there is a fault in your transmitter. You haven't said whether you assembled it or bought it fully assembled. I have a similar low power (25uW - that's microwatts) into a bit of wire about 10ft long and a water pipe ground and it easily covers my land and nearly all of the neighbours too. Read the book and check all the tuning.

A 60watt transmitter in your back yard will be illegal and soon attract the attention of the authorities who will likely take you to court and confiscate all your equipment.
 

n5ims

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Joined
Jul 25, 2004
Messages
3,699
Perhaps you should think about using something called "carrier current broadcasting" instead of and antenna based solution, especially if you attempt to use the higher power transmitter. Basically instead of an antenna, you couple the transmitter into the power lines of your home, building, or campus. This isn't as simple as directly plugging your antenna jack into a local AC socket, but isn't really too much more difficult. Many college campus radio stations started out using this technology to cover the campus license free back in the late 60s and early 70s. Many placed very low power transmitters in each covered building while others used higher power transmitters that fed the common signal, using splitters and coaxial cable to feed multiple nearby buildings on the campus.

Basically the RF signal from the transmitter was coupled to the building's power using an isolation box that passed the RF through to each side of the building's main power distribution panel. This isolation box not only passed the RF along, but kept the AC power from feeding back into the transmitter. Be aware that you need to feed each main power feed (two feeds for a typical home 230v AC system or three feeds for a commercial three phase AC system (some large buildings have multiple power lines, so multiple feeds may be necessary for full coverage). You will need an electrician to make the connection since it's done directly in the main distribution panel!

The signal should cover the entire building quite well as well as areas very near that building, especially if there's external lighting fed by that building's power. We fed the dorms and had good signal in the associated parking lots as well due to the lot's lighting being fed from the dorm power feeds.

https://www.hobbybroadcaster.net/resources/carrier-current-AM-broadcasting.php
https://en.wikipedia.org/wiki/Carrier_current
CBI Carrier Current and Part 15 College Radio Help
 

jpdesroc

Newbie
Joined
Jun 13, 2014
Messages
2
Like most of the answers on that other forum, IMHO there is a fault in your transmitter. You haven't said whether you assembled it or bought it fully assembled. I have a similar low power (25uW - that's microwatts) into a bit of wire about 10ft long and a water pipe ground and it easily covers my land and nearly all of the neighbours too. Read the book and check all the tuning.
I assembled it myself and it is operating correctly.
I tuned the antenna according to the manual description.
The reception is ok if I put my receiving radio
close (aside) to the 9 feet antenna..
But when other radios in my house are also receiving, their reception is ok
but poor in my opinion..

A 60watt transmitter in your back yard will be illegal and soon attract the attention of the authorities who will likely take you to court and confiscate all your equipment.
I know that. Even if I'm located in Canada and the CRTC (Canada FCC) restrictions are a little
less picky I should take that in consideration..
I will try positioning the antenna diferently..
 
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