A follow up on my post from a couple weeks ago, the transmitter in a bucket was thrown together today in the house and set up in a temporary location outside.
Range was 1/4 mile from an ungrounded 100 mW AM transmitter, the audio is being fed to the transmitter via a Sony Walkman tuned to 102.7 FM. I am using one of those FM modulators that plugs into a cigarette lighter inside the house connected to a laptop and power supply.
Without the ground i suspect there is no return path, because of the lack of ground the range is limited. Right now it is too dam cold to do anything else, i’ll pick this up when the weather straightens up a bit.
It is currently 30 º F in Busy,Ky and a very light snow is falling.
The time is 3:41 PM ET
Photo’s were uploaded today as well. http://busyradio.weebly.com/am-station-build.html
Interesting
I am not sure what I was viewing in some of the pics but it looks like the blue bucket is the featured item. Was that EMT (electrical conduit) you used for the radiator and was it attached at the top to the building for support?
The bucket is an easy to get enclosure and it should work well. Let us know of future progress.
By the way, you might be familiar with the “Rule of Maximum Inclemency” which states that an antenna’s performance is proportional to the inclemency of weather when it is erected.
Neil
One should never rush one’s words when…
Trying to convey their message.
Neil, I was in such a hurry that day that i left out a bit of important information.
I updated the pictures and descriptions on the website and i hope it all makes more sense now.
Yes the conduit is the antenna, i cut this to the exact length of the wire antenna then trimmed it down a bit more. There is a very short wire connected to the TH 5.0 and the conduit. I pieced it all together hoping the internal ATU would tune up without error.
It did tune up nicely on 1610 Khz. All that is left to do is get a ladder to climb up to the peak of the car port where i will attach the bucket to the peak of the roof using a piece of steel.
The steel plate will attach to the bucket using four nuts and bolts, the other side of the steel plate will be screwed into the wood just under the metal roof. The antenna will face away from the metal roof.
Power is obtained from an outlet under the carport roof and audio is fed to the AM TX using a Walkman tuned to 102.7 FM, the transmitter in the house is a cheap FM modulator which i did not post a picture of yet.
I hope this helps clear some things up a bit.
P.S. Neil, i was not aware of that rule.
http://busyradio.weebly.com/am-station-build.html
More Blue Bucket After This
But first, here is your CHRISTMAS BONUS from KDX Worldround Radio.
Available as a 10-minute feature for all stations:
http://kdxradio.com/archive_files/121213_blarelite20_128_V1.mp3
Haha! Thanks Carl.
That was a great bonus, it just kept on giving.
At any rate, as you may have guessed the transmitter in a bucket is a bit top heavy.
Today i ventured outside despite the below freezing temperature of 24 ᐤ and tied down the bucket with couple of tent stakes and twine.
The antenna started to fall towards me so i reached out to steady it while the other hand was pushing tent stake into the ground. At that point i felt a slight tingle, yup i completed a circuit between the ground and the antenna.
It wasn’t painful like say shoving a fork into an AC outlet , it was just enough to let me know it was transmitting. Good to know lol.
Guy Thing
You call it tent-stakes and twine, but those are guy wires just like the ones that hold up the big towers.
Now we know why they’re called guy wires, because it takes quite a guy to go out in sub-freezing weather and sustain an electric shock to keep the radio station in a standing position.
If your rig fell over you’d sing The Blue Bucket Blues.
Carl i used to be immune
To the cold having been born in Cleveland Ohio but recently i have developed tremors that my doctor said i have had for years. The tremors have recently become more noticeable especially in the cold or under stressful situations.
But that is not going to stop me from broadcasting 🙂
I have however run into a problem that has been discussed in great depth on Part15.us, that is the irritating hum of the Talking House V 5.0 and all the versions below that model. I will attempt to add a sound file of recorded from a radio tuned to AM 1610 with dead air , no modulation.
I will search around the forums here and try to get a handle on what is causing this horrible noise.
At other frequencies below say 1500 Khz the hum seems to either become less noticeable or non existant. I feel like RF is influencing the circuit some how. Perhaps the antenna is too close to the transmitter?
As i said before, a search of Part15.us should offer the answer i seek.
Below is the link to the audio file, warning! Bypass processing if you listen to this file on a high end sound system, the hum is annoying enough by itself.
https://soundcloud.com/rock957/datdamhum-am1610-blue-bucket-radio
Things i am thankful for?
Part15.us Library.
A vast ocean of knowledge.
http://www.part15.us/content/why-does-my-transmitter-hum-0
Hum
Barry, your probably have read some really good posts in the library about this and about all I have to add is that often the hum on an AM system (and also on FM) is not coming from the transmitter but rather from the electrical environment around the receiver. This is the case here at the 8Z compound. Though commercial broadcast stations may come in hum free the very much higher field strength of a Part 15 transmitter near the transmitter can interact with electrical items connected to the AC mains and cause hum in the signal received nearby.
Here, this is the case with line operated receivers, portables, and even on my truck radio when it is in the garage. Moving away from the house to the street gives a hum free signal. It is definitely not my audio or transmitter producing this hum.
But there is always a possibility of an audio chain or transmitter problem being at fault and the easiest way to tell is to check if the hum is present when the receiver is out in the open away from wiring.
Neil
Neil is right
And i heard the hum at 1/4 mile from the transmitter so it is probably the power supply but i am also hearing a seperate hum that sounds like maybe a bad patch cable that feeds audio from the walkman to the Talking house.
When It’s the House Wiring and Pipes
As Barry is presently detecting, there are numerous possible sources for hum in the audio received from an AM part 15 transmitter, and I don’t know what his immediate problem might be, but it sounds like everything is being checked.
Meanwhile, I have started thinking about one type of situation that has been talked about several times here on several forums… that is hum interference coming as a result of inter-actions with house electrical wiring as well as other metal located within the transmitter field such as pipes and metal storm/screen doors.
When I carry my Grundig portable out the door listening to my AM 1550, the metal storm door makes a lot of static on the radio while I’m opening it and just touching it by hand changes the signal level on the radio.
My next stop is always the porch stairs with a metal railing that raises and lowers my carrier level if I touch the railing.
My guess is that all the metal in the near-field is receiving and reflecting my station’s RF signal and by touching it I am de-tuning it in various ways.
While I was running my 13.560MHz transmitter with a room-to-room 17′ dipole antenna the indoor reception was loaded with hum, but outdoors there was no hum at all, so it must have been from the AC wiring in the walls.
Can the house wiring and maybe even other metal objects be provided with filter circuits to make them shut up? I want to start doing that to neutralize the near-field environment.
It gets weird from here on..
Here are a few things i have tried so far:
1. Disconnected the audio cables, hum is still present.
2. Recorded a generic message onto the memory chip, hum reduced but still present.
3. Tried a few lower frequencies, 1000 Khz, 800 Khz and 530 Khz*
4. Finally, no antenna at all connected to the TH. Hum was gone but signal was greatly reduced.
About the only thing i didn’t try was an external antenna on a loading coil with the TH set to Outdoor Antenna. That doesn’t mean it won’t work, but i have a feeling the source of the hum is the power supply.
I have had two other Talking House transmitters before this one, both of those were TH 2 versions and only one of those the hum was not there. Another option would be to try loading up an extension cord by wrapping the antenna wire around the extension cord and letting the built in ATU tune it up.
I really don’t want to do carrier current unless it is a last resort.
Option number 3* the lower in the AM band i went the less hum there was but of course the trade off was less power output to the antenna.
It has to be the power supply as 800 and 530 Khz both showed very little hum which leads me to believe the transmitter uses less voltage at the lower frequencies thus eliminating or at least limiting the hum.
Any thoughts?
Edit: The hum was present when i had the TH 5.0 inside the house as well.
Noise
Barry, I would characterize the audio in your sound sample as “digital” noise, not hum. The word “hum” best describes the bass tone at 60 Hz or 120 Hz of caused by the interaction of the RF signal with the power wiring. The fact that you still hear the hum a quarter mile away indicates it is being radiated by your transmitter. AC wiring radiated hum tends to disappear as you go farther from the transmitter.
Are you using the standard Talking House power adapter, or did you substitute a different adapter? A poorly filtered switching supply will introduce a raucous digital noise such as in your audio sample.
Hello PhilB
Yes i am using the Talking House power supply which i knew i would regret and it appears i had good reason.
I wonder now, besides trying another power supply which i will have to do when i can afford it, how would the power meter at my home affect this transmitter if it is using carrier current to send readings to my power company?
I never considered this until you chimed in Phil, but that is how they read the meters out here. At least i assume it is, no one checks the water meters either.
No human being ever shows up here to read the meters so i am assuming since the meter is digital they must be sending it by carrier current.
Would that mess with my set up?
looking for antenna help!
Hey folks i must admit im new to LPFM i just got a (i am radio. talking house transmitter) and now looking to set up my attena to test it out it will me mounted on a 30 foot tower. Can anyone tell me how a procomm PT99 cb base antenna would work for am broadcasting? and will RG6 or RG8 be good, also would i be better to place the transmitter in a weather proof case on the tower not really wonting to do that but im worried about the loss over 75 feet of cable with 100mv? any ideas or help would be Greatly Apprecitated!