in short 15.219 does not and will never work in an apartment setting. i have tried rangemasters, amt5000's, thII's, iAM.
in short 15.219 does not and will never work in an apartment setting. i have tried rangemasters, amt5000's, thII's, iAM.
nothing under 219 works to cover my small complex here even outdoors and not even with a 3 meter long ground lead. there is just too much RF absorbing material coupled with very little ground conductivity.
also the SSTRAN AMT5000 has a very tight tuning window. it wants to see a very specific load in order to reach a peak.
these tx's often do not lend themselves to ground radials. they work best at ground level no more than 1 meter with just a simple 8ft ground rod and a 1m ground lead coupled with 102" steel whip.
they will not properly load over a full ground radial system or even a partial.
if you go to the mid to low frequencies than a very minimal 4 x 10ft radial system might work but in the x band with these simpler is better.
these results are from months of extensive testing different ground scenarios and configurations, and locations using my professional test gear (FIM, O-Scope, SA, Portable Rx) to evaluate these setups
How well does the wire antenna work at your place .
I have found in some cases that is the way to go.
As I pointed out before, either a simple wire or the Isotron or similar style antenna works best for apartment situations.
Apartment buildings are built with heavy insulation and with a Faraday cage approach having wire mesh within the walls. Plus all the plumbing and electrical wiring adds to the headache.
Further proof was when you tested this stuff near the pool area and got excellent results with that TX on a tripod and simple ground, further proving that 219 setups work best at ground level, even when surrounded by iron rod fencing.
I love real world tests. They reveal far more than the bench or simulators ever will.
RFB
I remember that you, kc8gpd, have had experience with carrier current, and now that we are talking about penetration WITHIN an apartment complex, I would think that carrier current would do the job better than any other legal method.
But if that is true, you would already know it, so I wonder why carrier current is ruled out?
If we go into a complex, believe
me - I will try to work on this
problem.
Time will tell.
Bruce, W 60 HZ, X-13
Robert, that is not good news about your tests. I hope you keep trying and find something which will work.
When I taught college I used a Ramsey AM25 transmitter for a lab experiment. A simple 3m wire was strung floor to ceiling and the power line ground was used as a ground. The signal could not be heard in the hall about 30 feet away from the lab yet the signal was readable in the parking lot a couple of hundred feet away. This was a poured concrete building with brick facade an within the building the signal got almost nowhere.
Neil
k8gpd said:
"also the SSTRAN AMT5000 has a very tight tuning window. it wants to see a very specific load in order to reach a peak.
these tx's often do not lend themselves to ground radials. they work best at ground level no more than 1 meter with just a simple 8ft ground rod and a 1m ground lead coupled with 102" steel whip.
they will not properly load over a full ground radial system or even a partial"
If you have a problem tuning the AMT5000 to your experimental antenna/ground setups, it's likely to be caused by either abnormal antenna capacitance (outside the range of 19 pF to 37 pF) or extremely high ground resistance (much greater than 100 ohms). A 10 ft wire antenna will tune even with no ground other than the capacitive coupling through the AC adapter. It will also tune a 3 meter vertical wire, whip or copper pipe (elevated or not) over earth with all sorts of grounds ranging from a single ground rod to an elaborate radial system.
Even antennas that have capacitance above or below the normal range can be tuned by coil tap selection. The tap won't correspond to the one suggested in the tables in the manual, but can be found by experimentation. Of course, extreme low or high antenna capacitances may be outside the range of all the taps.
To put it mildly, indoor operation is a total crap shoot.
Everyone would dearly love to achieve 1 mile range with an indoor antenna. Over the years, I have never heard privately or read on the Internet of anyone achieving any significant range with an indoor antenna of any sort. OK, I don't want to discourage experimentation, but that's the situation as of now.
There are reports of, and I have personally experienced, significant signal strength along overhead power lines for about 1500 ft or so from an indoor antenna location. The distance from the power line is extremely limited. It is even noticeable that the signal is much stronger travelling in one direction vs. the other, the difference being 10 ft or so between the two road lanes.
Inside a single home, the signal is typically strong and can be attributed to AC wiring radiation. A portable radio placed next to a power outlet or power cord comes alive dramatically.
Inside a multi-unit apartment building may be a different story altogether. If it is a small wood multi-apartment "conversion", then reception in the building will probably be similar to a single home. But, if it is a large, reinforced concrete apartment building, it will most likely be subject to the "Faraday cage" shielding mentioned above in this thread. That's a real signal killer.
Carrier current operation for a large reinforced concrete apartment building may seem like a viable alternative, but there are variables that may kill the idea. It depends on the power distribution scheme to each apartment. If, as is likely, each apartment has its own power meter and main breaker panel, the carrier current signal will be shunted to ground at each panel. The only remaining path for the RF signal will be through the walls (Faraday shield), so you end up with a fail either way.
As I said, I don't want to kill experimentation. I am only relating what I know to date.
There was a time when I had a really
good 15.219 outdoor ground mounted
system with the AMT-3000, and at
that time - I did have programming.
The above was my most successful
Part 15 venture ever.
But right now, for me, it's just
going to be about the experimentation.
With the Part 15 13 MHz transmitter
working very well, I have gone back
to Carrier Current and the idea of
the transportable 15.219 system with
the AMT-3000. This will keep me busy
for a while.
And if we do end up in an apartment
complex, I will be very interested
in experimenting with this indoor
idea.
It seems to me you could tack an antenna
to a picture window (sort of what
Carl is doing, ground the transmitter
to a radiator or something like that)
Or make a counterpoise - - and in addition
to the wire antenna you could
then use another wire for a 2 element
top hat, which you could also tape
to the window. You could use thin wire
so nobody would be able to see it. The top
hat would pull more current up into
the antenna, I guess.
For me, it's just another experiment.
Bruce, W 60 HZ, X-13
"Carrier current operation for a large reinforced concrete apartment building may seem like a viable alternative, but there are variables that may kill the idea. It depends on the power distribution scheme to each apartment. If, as is likely, each apartment has its own power meter and main breaker panel, the carrier current signal will be shunted to ground at each panel. The only remaining path for the RF signal will be through the walls (Faraday shield), so you end up with a fail either way."
About 1/3 correct in as far as apartments having their own meter and the building like a Faraday cage (see my earlier post).
As to the signal shunting to ground at every panel, bogus.
Every single meter and every apartment in the building get's the same hot feed from the main service in front of each meter and panel. Couple to one or both hots, every single hot in each apartment will get that signal unless a panel has it's main breaker turned off.
Every single apartment will have the same neutral within that building as well. Again each getting the signal. Only issue with neutral coupling in an apartment building is finding a good return path. Using a proper coupler which can match up to .1 and less ohm, it's usually not that difficult to find a decent return path..such as cold water pipes.
Apartments are no different from dorm buildings. None of those dorm setups ever experienced their signal shunting to ground at each dorm room's panel, hot or neutral coupling.
I encourage experimentation. I am relating what I know to date spanning 3 decades of working CC, in all kinds of different setup situations. Yes each has their own little kicks and twists to overcome. After 3 decades of building out CC systems for many clients and users, every single one required a different solution to overcome problems. But not a single one of those problems was a signal shunting to ground at the panel.
I think your AMT5K is a very good unit. Only fault with it is it's incredibly narrow tuning window..requiring a narrow array of antenna variant. Unfortunately not all setups are going to be within that narrow window.
I'm surprised you don't have commercial transmitter manufacturers knocking down your door offering millions for that 98 percent efficiency.
Curious though that to date only one person has demonstrated the limits of the unit reaching satisfactory results beyond the simple wire. But that in of itself is a plus for apartment dwellers. It works better with that simple wire and perhaps enough to get satisfactory results to cover a complex.
Kc8 did report that when your unit is sitting on a tripod 1 meter in height over nothing but a ground rod it worked really well, even with rod iron fencing all over the place.
There are a lot of apartment dwellers these days. The reports given are valuable to those in such cases. Not all is lost.
RFB
Do we have any apartment dwellers here who have had success and wish to comment?
Beyond my experience with college CC in the dorm, I did set up my Knight Kit in my room with a 10 foot wire antenna and was able to provide a solid signal to both ends of the hall in the building. I predict that with some experimentation it can be done. Keep in mind that success or failure also depends on the criteria used as a measure. For example, a 200 foot radius sphere of three dimensional coverage in a multistory apartment complex can include more potential listeners than can 1000 foot radius two dimensional coverage in suburbia. Perhaps the potential listener number is a good criteria to use other than linear range.
Neil
i removed the ground radials just left the rod and wire. trimmed the whip i measured at 129" to 102"
will try and re-tune and check range when i have a chance. my fim cuts off at 1600 so i can't measure at 1670.
just have to rely on my portables meter and my SA which i dont have a calibrated loop or fm dipole for.
when i get those i will be able to do medium wave and vhf compliance measurements then.
I am suggesting a shift in thinking based on the fact that FCC field strength measurements are made outdoors and not indoors.
Therefore it may be a needless exercise to use 15.219 when operating an indoor system under part 15, when the target audience is within the same building.
I would say that 15.209 would be the better choice for indoor installations, in which case only the field strength outdoors would count in evaluating compliance.
Thus opens the way for trying bolder indoor antenna systems which stand a better chance of increasing the reception area within the building.
At the same time this gives up the relative simplicity of using the 3-meter rule.
15.209 field strength is lower than what you will get out of an outdoor 219 system field strength at the same 30 meters.
Complying at 209 indoors would in effect be a weaker field strength than complying with 219. Adding the attenuating effects of the building materials etc, would most likely make the 209 route less optimum.
If installed correctly and coupled correctly, a CC system is your best bet. And then again, a combination of 221 and 219 can overcome the obstacles.
RFB