This website has been very helpful and eye-opening. The fact that I can legally operate a Part15 AM station is a childhood dream come true.
This website has been very helpful and eye-opening. The fact that I can legally operate a Part15 AM station is a childhood dream come true.
That being said, I purchased a TH 5.0 and live in a 5 story apartment building in a north side Chicago neighborhood. Myself, along with a few others in the neighborhood, would like to offer some community-based programming - hopefully with several transmitters throughout the neighborhood in the future. We may have rooftop access at a local business down the line, but for the time being, I would like to get something up and running from my apartment. That being said, my options as an urban apartment dweller seem limited.
Freestanding, outdoor antenna options are not an option. I experimented with the TH 5.0 included 3 meter wire hanging out my apartment window. It gets me somewhere around a block of range, with a very weak signal. I also experimented with a horizontal 9ft length of 3/4" copper pipe with a lead hooked up to the supplied antenna output on the TH on my window sill (very amateur, I know... but worth a try!). My only outdoor options that I know of are my window sills. I think the 3 meter wire option actually worked better than the copper pipe.
Not knowing as my as I would like to about viable options, proper antenna tuning and the sort, my goal is to get my signal out there a couple more blocks, if possible. I know that my apartment situation might limit the possibilities. Any ideas? Thanks in advance for your input.
~Railroader
Multi-level buildings such as apartments do indeed present their own unique set of difficulties, mostly finding a decent ground to work off of, not to mention the placement of the radiator element which in this case is a 10 foot piece of wire.
The ideal approach here may be a combination of both antenna wire and carrier current. The carrier current approach will provide the clear signal in the buildings while the antenna wire approach would do the "fill in" for the far field. This no doubt would require other transmitters co-located acting as repeaters or relays, and on different frequencies.
Try this experiment. Take the 10 foot long wire, wrap it around an extension cord (yard type) and plug the extension cord into a power outlet near the breaker pannel. Let the TH unit fire up and auto tune itself with the antenna wire wrapped around the extension cord. This is a basic form of carrier current coupling and it should provide a crystal clear signal in the entire building, and perhaps a little bit of coverage through the air nearby..perhaps a block or a little less.
RFB
Thanks for your suggestion! I tried the carrier current method and I think it did increase the audio quality within the building. No surprise, it seemed to limit it outside the building.
Just for kicks, I put the antenna wire back out my window and went down the basement to see if there was a signal. Keep in mind that this is a 5 story, concrete and brick construction structure. Low and behold... the signal was still fairly strong! The Talking House must be using the ground off the ac fairly effectively.
My main objective is to get the air coverage increased another couple of blocks. I am interested in learning more about what you're getting at when you say "other transmitters co-located acting as repeaters or relays, and on different frequencies."
Anyone else with ideas about increasing range under these circumstances?
My AMT 5000 is indoors on the 1st floor of my 1-story building, located down at the baseboard below a south facing window. A vertical antenna wire about 2.5-feet in length runs up the wall and underneath the closed window, and is electrically attached to the outer aluminum window frame about 4-feet vertical height with a self-tapping metal screw. This brings the antenna length to about 6.5-feet.
On the outdoor top of the aluminum window another tapping screw attaches a further length of vertical wire that rises until a total length of 3-meters, including the window and baseboard wire, is reached.
The ground is run down the baseboard straight into the basement where it attaches to a single "ground radial", a long copper heavy-gauge wire that runs under the soil up the back hill about 150-feet. At this time I do not have a safety ground-rod on this transmitter.
The advantages are 1) the transmitter is indoors; 2) the signal very effectively covers the indoors and on the outdoor side covers about a block and a half in all directions; 3) like-a PZM microphone (Pressure Zone Microphone) the RF signal is in-phase with the building surface and thus travels all around to the front of the building by the "skin effect".
A disadvantage is that capacitance reactions with the building wall are believed to reduce the more effective radiation that would occur out in an open space.
If you have a metal window frame you could try the same thing.
That's an interesting suggestion, Carl. I do, in fact have a large, aluminum frame window that is just over 9 feet long and about 4 feet tall. I wouldn't be able to run a ground like you did, as I am on the 5th floor of a city apartment building.
Just to clarify, you're running a short length of wire screwed into the bottom outside of your window frame? Then, you've got a second wire running attached to the top frame running horizontally? Your description is great, I'm just having trouble picturing it.
I'm curious as to how would this outperform a simple 3 meter wire dangling out the window?
The antenna wire from the transmitter is on the indoor wall running vertically up to the window well where it goes underneath the closed window and is screwed to the aluminum frame on the inside bottom of the frame.
The outside wire at the top of the frame is screwed from the outside.
The window well is essentially an aperture, that is an open space where there is no wall. I think glass is transparent to RF. I believe a wire against a wall is somewhat absorbed by the wall whereas the window space is free of wall and the metal is carrying RF signal.
Using the AC building ground or a firm cold water pipe ground should be very beneficial.
There is another technique used by hams for apartment setups, running a long wire all around the baseboards for many feet to serve as a kind of ground. I would like to try that sometime.
RFB posted a site that sells pre-built antennas that might work well for your situation. Scroll down a ways in that thread.
Thanks! I'm not finding that thread. Can you please post the link?
Talking House literature advises to run the antenna wire up a all, not a window. They feel that glass blocks the signal.
So much for glass mount antennas.
That's interesting MRAM 1500 for two reasons.
I thought in previous forum/blogs it was reported that RF passed through glass...
And, I thought that it was strongly NOT advised to mount an antenna against a wall if at all avoidable.
Am I wrong twice in a row, once in a row, or .....
IMPORTANT EXCEPTION!!!!
The metal window frame is not covered by glass and is exposed to the outside, and if there is an inner window I find in my experience the house is very well blanketed by solid RF, and the result has been better for me than stretching the antenna up either an indoor or outdoor wall.
"Talking House literature advises to run the antenna wire up a all, not a window. They feel that glass blocks the signal. So much for glass mount antennas."
LOL!
If the glass has a layer of heat/light activated shading or by power or if it that might dampen the low power signal off the wire and affect the internal ATU tuning. I don't think a normal clear piece of glass would matter that much.
RFB
The loop link didn't show up but ....
http://www.antennas.us/store/p/326-LL-1001-396-600-1600-kHz-Omni-Antenna-AM-Antenna-.html
&
http://www.antennas.us/store/p/327-LL-1001-396-CF-Custom-Tuned-Omni-Antenna.html