Hello from KDXradio.com, where Part 15 is a way of life.
Hello from KDXradio.com, where Part 15 is a way of life.
Last night we closed 1550kHz which was feeding the famed Southern Wintenna (window frame antenna) which served as a test site comparing our new AMT5000 with the AMT3000 which had been there for several years. The comparison tests are documented in a much visited thread on this same website.
We moved the AMT5000 to the front facing Northern Wintenna, much better located with hilltop exposure at 1680kHz to the neighborhood below. Another AMT3000 was removed from this location, giving us two AMT3000s that are out of service for now. The AMT5000 was tuned up and turned on, bringing a new “Part 15 gremlin” for us to wonder about.
On many radios in the building the signal from the AMT5000 has a deep hum, but we quickly proved the hum is not being generated by the transmitter itself, but somehow is only being heard on some nearby radios.
Taking our Grundig FR-200 portable radio on a good walk around, there are many locations where the signal on 1680 coming from the AMT5000 is perfectly quiet with no hum at all. Also of interest is the fact that the AMT3000 had no such hum artifact.
This particular kind of hum interference is described somewhere in the maze of site information, possibly from Radio 8Z or MRAM, and we’ll study what has been said.
Our shortwave transmitter, Big Talker, at 13.560mHz, has the same kind of hum accompaniment on some radios, but not others.
On a different but related subject, I found a perfect lamp (Lowes 14.95) for installation at the transmitter, which otherwise resides in a shadow. It is an LED lamp that looks like the spout of a lawn sprinkling can mounted on a thin gooseneck with a clamp that attaches firmly to a windowsill. The quality of light is perfect and I think every transmitter location needs one.
Slogan of the times: “Occupy 1680.”
New Lamp, New Noise??
Hi Carl,
I am wondering if maybe the hum you are hearing might have started when you brought the new LED Lamp into the internet building. The circuits in those things are horribly notorious for spewing out noise. On the other hand when they quit working the parts “if any are salvageable” can be used to build transmitter circuits.
Did you try unplugging the lamp and listening for the hum?
Good Idea
Rock 105.3 you said “try unplugging” which I did not try. I did turn the lamp off, which didn’t make any difference, but….. right now, while this window is still open… I’m going to unplug the lamp….
IT FIXED IT!!!!
Rock 105.3, you are a genius!
No more hum at 1680!
Party time everybody!
Part 15 Changes of the Day
The AMT5000 has been tried on both my Southern Wintenna (antenna in a window) and the Northern Wintenna. It definitely likes the Southern Wintenna best, and is now providing daily service at 1680kHz.
For some reason the Northern Wintenna likes the AMT3000 and does very well, so it is providing daily service on the newly re-opened frequency of 1550kHz.
Rain and rain has slowed progress on the planned outdoor antenna site, but design of the ground radials is continuing on paper. When the outdoor structure is complete it will be employed to compare both transmitters for efficiency at 1680kHz.
The outdoor 13.560mHz 22-meter antenna is still lacking an exact plan, but there’s a piece of blank paper dedicated to that.
Farther in the future is the long wave outdoor antenna and transmitter.
Carrier current is still up in the air due to lack of proper equipment.