I am pleased to announce that 1700 am is covering 1 mile with a reasonable signal and good modulation.
I am pleased to announce that 1700 am is covering 1 mile with a reasonable signal and good modulation.
The transmitter making all this possible is one of the TH2’s i bought last month with the unit still in my mobile home!
With the antenna in a L-shape and adding extra ground I was shocked and amazed that I could copy my signal at greater than fifty feet from the house. (using the factory stereo in my minivan)
Now the modulation could be louder but it is listenable at 1/2 a mile from the house and a bit noisy at 1 mile out. I believe it could easily cover 1 1/2 miles but several factors play a role in limiting the stations coverage.
The metal siding, the antenna being inside, low modulation and grounding.
As for the grounding, I used a F- connector by itself (no cable connected) and soldered a short length of copper wire to it.
Connecting this wire to a grounding screw on the outlet the TH2 was plugged into.
I have plans to add yet another ground to a rod outside of the house but for now this seems to do the trick.
One more thing too, i was on a road that runs behind walmart which is just about 1 mile from the house. This road is higher than walmart, in fact you can see the roof of the store and count the AC units on top.
From there you can also see the mobile home park i live in too, my station of course got louder there.
If I would have thought to do this i could have gone back to the automotive dept. of walmart and tried to pick up 1700 AM on the car stereo’s they have on display.
Anyway a small victory for my flea powered radio station.
Feet on the Ground
Kudos there Rock95seven for not giving up.
I’m curious to know if you are using the power supply that comes with a TH2. Given that the original power supply connects the chassi to the ground pin of the AC connection I’m surprised that the ground added using the F connector made such a drastic difference. Perhaps, if you are using the original power supply, the grounding wire is broken. You can check that with an ohm meter.
But then, why bother if you’re getting that kind of coverage. Also, you may find that the signal is following the power lines. Do you notice if the signal drops off rapidly if you are not under the power lines? But there again, so what! If the signal is gettin’ out there, mission accomplished.
I am using the TH2 power supply
and i checked the ground on the power supply after reading your post and it is still intact.
The station does follow along the power lines but is also present when there are no power lines in plain view or along the road. The signal does get weaker in some areas where power lines are not present but it is still audible.
One thing i want to check out too is coverage to Interstate 75 since it runs along side of me there might be good signal there although for a very short time as the speed limit is 70 +. lol
The local Shell station is also a truck stop wich is less than 1/4 mile from my house and is right on the off ramp from I-75.
I might ask the owners of the Shell station if i could post a flyer in the window to urge patrons to tune in. The Shell station sits quite a bit higher than I do and should have clear reception of am 1700.
Other potential listeners would be in three motels that are behind me and have a good chance of hearing my station as they are well within the strong portion of 1700 am.
Everywhere i went that yielded a strong or usable signal had powerlines around it and i really didnt drive much further than a mile from the house. I was just out getting some things from walmart, the station was just a bonus.
Changing Conditions
So we all know how it works, weather conditions can affect our low powered stations just as much as it does high powered stations.
The only difference , it is more noticeable on a 100 mW station.
Today I was out with my wife and wanted to show her how well the station could be heard around town. Only trouble was it was there but atmospheric static was in there too so the modulation just didn’t pop like it did the other day. (a sizzling or frying static)
If I recall correctly, the other day was a nice day just as it is today.
Temp was close to 80 degrees and humidity was 20% with no wind, maybe a few puffy white clouds here and there.
Today was pretty much the same with only slightly more humidity and in the mid 80’s and a slight breeze.
What could have changed in a few days?
The signal wasn’t covering as much area as it did the first day i received my station on 1700 am. I made no changes to the transmitter, antenna or ground. Everything is the same.
Coverage in the mobile home park is unchanged, you can still pick it up around the park with little to no trouble on a car radio and i assume you could with a walkman or portable radio as well.
When it rains here, the yard becomes a swamp and would saturate the soil which should make for a better ground conductivity.
This part of Kentucky has the poorest ground conductivity i have ever seen anywhere.
Has anyone else lost coverage with their AM Station as well and if so what do you feel was the main cause ?
I should mention also that I don’t know what time of day it was I listened on both day’s but time of day may or may not have affects on our signals, if it does then it would be the position of the sun in relation to the horizon and the charging of the atmosphere.
In my mind it makes more sense to add more ground for my signal to bounce off of.
Also just because it was sitting around collecting dust i decided to fire up the second TH2 and placed it on 800 am with a same-milcast of 1700 am. lol
My FM transmitter for 97.7 will probably find a new home at my son’s house 20 miles away with his own station as soon as I can get over there to set it up for him.
Ahhhh Proper-gation
Yes, I experience this almost everyday. Weather definitely affects it as do the seasons. But all other things equal the time of day alters my coverage drastically.
My best time seems to be 10 am to 3 pm depending on DST.
If you have seen my coverage map, the main road just south of me is Howe Road, my benchmark. On a good day my usable signal starts just east of the expressway at Main Street and traverses the entire length east to the next major road, Tallmadge Ave. Depending on time of day the signal goes from barely there to loud and clear.
Rain & Grounding
So Mram, how does rain affect your stations range?
I have a yard that holds water when it rains and given the poor soil conductivity it would seem that the added moisture would increase the usable ground?
I am almost hoping the storms i see on the radar would dump some rain on this yard so i can test this theory.
Today i took a drive around town to see how the 800 (now on 750) was fairing. It wasn’t there until i turned onto the road leading into the park here. (about 500ft)
Not sure what the difference is between the transmitters but i understand the higher frequencies tend to be a bit more efficient with short antennas for part 15.
1700 am was covering a mile again with a little less noise this time and better modulation. Actually listenable at 1/4 mile or more.
I’ll play around with 750 a bit more and leave 1700 alone lol it’s working!
Anyways i would love to hear what affect rain has on your range as well as anyone else running AM.
Thanks
Carrier Current Ground
Having just come out of the snowy season, I did notice my coverage was always better when there was snow on the ground. But then my antenna is on the roof so maybe it was the snow on the roof.
I don’t have much of a ground system under my antenna. It is mounted right above the TV antenna which is serving as part of my RF ground. I formed a coax balun from several loops of the coax just below the antenna hoping that would choke out RF on the coax.
As far as “free radiate” signal, time of day seems to have the biggest affect. Next would be the moisture.
In the immediate area the power lines are the biggest factor. Since the Talking House is “grounded” to the AC ground, I think the tuner is working the antenna against that ground for the most part which makes it almost like a ground loaded carrier current operation.
Propogation can be weird
Propogation can be weird. In my previous location, where I had originally setup my station, I was getting a decent one mile coverage before things dropped noticably. After that, the signal slowly faded out. One unusual exception was behind the Lowes hardware store, about two miles away. In an area about 1/2 block wide, the signal was very strong again. Outside that 1/2 block, it was barely audible.
You got that right
At walmart which is 1/4 mile from my home, you can park in the walmart parking lot away from power lines and hear my station pretty decent but when you park close to one of the light poles in the same parking lot my signal jumps up out of the noise almost as clear as it is when your sitting in front of my house.
I didn’t try the car stereos in the store but i did try the display boomboxes but got nothing but noise or nothing at all since most of the stereos they have on display don’t have the am loop antenna plugged in.
Next time i will make it a point to try out the demo car stereos.
But you got me curious now Mojoe, I wonder about the lowes here by me which would be about 1 mile from my house. They seem to be on the same set of powerlines that feed my road and the main road to the park here. Come to think of it kmart and some other retailers are on the same line I am. HMMMM? I wonder lol.
The only thing i haven’t seen is a road that does not have power lines on it that would be within say 2 miles from my house, but then again i haven’t had a chance to cross the overpass to see what happens on the other side of the interstate. I don’t think the power lines crossover I-75 unless they go under the bridge.
I’ll have to try that in the next few days just to see where i can actually cover. As MRAM said, the tuning system on TH Transmitters may very well be working off of the ground on the power cord.
So I might actually lose my station on the other side of I-75.
Only one way to find out, when i do, you guys will be first to find out the outcome. Until then, keep rockin’
Part 15 AM propagation
Although Micro1700 isn’t currently on the air, when
it was (and it will eventually come back) I had some
very interesting propagation.
The test set-up was a Ramsey AM-1 modified for
crystal control running into a tuning coil that was
about 22 turns of #18 wire around a hardware
store bucket. (ACE, hardware, to be exact.) I had
audio EQ and audio processing in front of the AM-1,
which helped it quite a bit. The antenna was a
slightly less than 3 meter copper pipe sitting on the
ground over an insulator. The antenna was attached
at the bottom to a plastic shipping crate with tie wraps.
Inside the crate was a cinder block. This kept everything
steady. The ground system had 19 radials, most 20 feet
long, some ten feet long.
In the near field the signal was pretty big, but after about
200 feet it dropped off real fast. However, on sunny dry
days, I could hear the signal in hot spots 2000 to 4000
feet away on the car radio. The coverage area was not
a circle but more like a figure 8 pointing north and south
from my location. When it rained and the ground became
wet, the far away coverage would disappear.
I think the water in the ground was detuning the whole
system. You would expect it to work better with the ground
soaked with water, but it didn’t. Weird!
The AM-1 has been retired. I cannot verify it’s power input,
so I am not using it. I have an SS-Tran which I hope to
have up and running.
Best wishes to all!
TH II coverage
I recently put my TH II back on the air, and I configured my antenna in an “L” shape, as well. I am astounded at the coverage I’m getting using my Toyota radio as a reference. It’s a good 3/4 of a mile. Considering terrain and a few other factors, it’s doing very well and I am pleased with the coverage. The coverage in the other car isn’t the same, but it has a very poor AM section. I consider it to be more real world, and even on that radio, I am getting almost 1/2 mile.
The main problem with the TH II is that’s it’s easy to overload the audio input. I had bought a Broadcast Tools distribution amp to feed the AM, but that overloaded the transmitter. In the end, I used a small mixer to mix stereo into mono and I’m using the amp as isolation. The net effect is that the transmitter now sounds great. It’s not Rangemaster quality, but it sounds really good. Considering what I paid for the unit, I’m also pleased with the sound.
Grounding using the F-type connector
I am also using the TH2 transmitter, I have some questions about the grounding that I hope you can clarify a bit more. In the previous posts, it states the antenna is in an L shape which I understand. Is the antenna the factory antenna connected to the built in antenna tuner or is it connected to the F connector? I noticed someone said they only connected their ground to the F connector, is the factory antenna still connected in that configuration or is the antenna hooked to the external F type in additon to the ground wire? They said they hooked to the power outlet grounding? From what I gather at this point, the factory antenna with tuner is connected and an additional ground was supplied by the shield side of the F type connector and soldered to the chassis ground of the transmitter itself. Is that correct? I too would like to get out further than 50 feet. Any additional detail to this configuration would be appreciated.
Grounded TH2
Josh,
I grounded the TH2 using the F connector only because i had some concerns as to whether the power supply was actually grounding the unit or not.
After grounding the TH2 using the F connector I noticed by accident that my station was covering a 1/4 mile compared to the 50 or so feet i observed prior to adding the extra ground on the F connector.
My antenna is connected to the built in tuner and is in the L shape because of the low ceilings here in my mobile home.
The F connector does not have any coax attached to it, just a piece of 12 gauge automotive wire soldered to the connector. It just made it easier to disconnect the extra ground by just unscrewing the F connector.
I tested the coverage without the F connector/ground and coverage was the same. Clear reception on 1700 khz was 1/4 mile from the house, at 1 mile the signal had static but was still listenable.
There are some hot spots that spring up all over town here in London,ky.
Two hot spots are: Bobs Big Boy at just barely past 1/4 mile it sounds just like your sitting in front of my house.
The second hot spot is 2 miles away close to the London Utilities office where i pay my water bill !
So in my situation i feel like the extra ground really made no difference in coverage but with AM Antenna systems the more ground you have to bounce your signal off of the better.
I have one major factor working against me using the TH2 inside the house which is the metal siding on the mobile home. I probably could cover more ground if it was made of something else.
One thing the Talking House manual says it to make sure the wire antenna has some space away from the wall and other objects that would affect your TH2’s performance , my antenna is roughly a foot away from the wall and 5 inches away from the ceiling.
Other than that, the only other way i can think to increase your coverage is to see if you can get the ATU Antenna from Ebay or download the pdf files posted here on part15.us.
TH2 ground and the F connector
Because there are so many sub-models of the TH2 it’s impossible to generalize, on some models there is a switch that determines which output is used, factory antenna or F connector.
In some units the F connector, hot and ground, are completely out of the output circuit unless selected.
For those units there might be other tie points to get to ground when the auto-tuner is in use. An experimenter should probably be careful if checking for that, and it’s still an unknown as to whether grounding the output in auto-tune mode would really help.
For Rock95seven, for some reason I keep picturing the old prop fighter planes with the long wire antenna going from the cockpit to the tail, and imagining you replicating that with a fine gauge, light colored wire a few feet above your mobile. If you connected ground to your mobile body shell it could get somewhat interesting…
The feeding is Mutual
Perhaps there is some mutual coupling between the aluminum siding and the TH antenna.
It’s possible that at just the right spacing, using the built in tuner, that it’s tuning up the whole trailer. There are methods (parasitic excitation) of coupling to a grounded tower by placing a radiator adjacent to the tower without actually being electrically connected.
I’m not saying you’re following accepted coupling methods but – Stranger things have happened.
RF is strange
Wich makes working with radio so much fun.
Scwis, i am a big fan of aircraft. Especially the vintage fighters.
You gave me an idea there. Of course anything i do here would have to be cleared with the rental managers but they have worked with me in the past as we were trying to figure out where to mount the AM antenna.
The tongue of the trailor is still attached to the home, it may be in my way when i need to back my minivan in to unload groceries but it just might be a good place to test out your theory.
And maintainance has already mentioned using the tongue or the front porch for mounting the antenna. The only restrictions they have here is No TVI and the antenna can only be 3 feet above the mobile home.
There is a ray of hope for my station here if i ever decide to put up anything outside.
MRAM,
I’ve seen seen how parasitic excitation works, if i am not mistaken that is how some of the AM powerhouses direct their power towards their target audience. I think a good example of that was the AM station in Columbus Ohio.
It has been a long time since I have traveled North on I-71 but I seem to recall a big AM station on the southbound side of I-71 that used three towers in that same way. At least that is my take on it, i could be wrong. I wonder if the same technique would work on the duct work under the home? Maybe a good ground? lol probably would be pushing part 15 limits.
Anyways, my TH antenna is 6-7 inches away from the wall and the top of the antenna is 3 inches away from the ceiling. The antenna is in the L pattern because of the low ceiling.
Both Mram and Scwis have given me something to look into and now that the weather (when its not raining) is warmer I can tinker more outside.
Thanks