Well, it was bugging me last night. I just knew the skeptics and naysayers would look at my previously posted video and scream that it wasn't valid because I wasn't in a field, away from trees, the house, etc. Now, even though I knew it would make a marginal difference, I decided today to head back to the field (although I didn't hike out as far as usual) and make a similar video to the previous one, only this time, out in the open. So I did. It didn't make the trasnmitter any more legal. Taking into account variables like positioning of the power and audio cables (you noticed in the previous video they vary as you move the cables) the difference between open field testing and front yard next to a pine tree and an enclosed porch (no metal in the porch however, it's all wood and glass) is really quite negligible.
Then, I figured as long as I went to all this trouble, and people had asked, I moved the transmitter and meter out to 30 meters apart (98.4 feet) to get a field strength reading at the Canadian distance. Now, you'll note in the video the reading at this distance is 260 uV/m (.26 mV). Which, once the antenna factor is applied is a field strength of 585 uV/m. I believe the Canadian limit at 30 meters is 100 uV/m, correct? Uh oh!
Couldn't decide if I should add this video to the other topic, or start new. I guess I decided on starting a new one.
Video is at:
TIB
That is really fascinating, Tim, getting a true look at what the CM-10 looks like in both U.S. and Canadian terms.
30 meters really looks far away on the camera, which, by the way, records very clean video and clear audio.
If I give up the car maybe I can afford one of those meters.
What was the F.C.C. thinking when they allowed the hobby community to have FM privileges that almost no one is capable of measuring?
The fact that several literally CERTIFIED FM transmitters are radically over-powered seems to suggest that the F.C.C. is rather cavalier about checking what's going on in their certification department.
Who takes a fall if a certified transmitter is too strong? Why, we do. The users get busted. We are "fall guys" and scapegoats. We've been set up! They framed us.
Oh, for a minute there I got carried away.
Another excellent video, Tim. Who (legitimately) could deny the relevance of your measurements for those conditions?
Presumably your measurements taken at an h-distance of 3 meters used the "US" setting for that transmitter.
Were your measurements taken at an h-distance of 30 meters made at the "Canadian" setting of that tx (if it has one)?
As far as I know there is no user adjustable switch for US or Canadian. I was supposed to have been sent a US model (since I'm in the US of course). I'm told the change is made internally and buyers are shipped the correct model. I didn't want to take this apart any further than I did to test the RF output so I could put it back together to sell. The label on the bottom says it's Part 15 and Canadian certified and has the standard FCC Part 15 disclaimer on the bottom.
So both readings were taken at whatever the transmitter is built for. Oddly, even at 30 meters it's well over for Canadian limits as well.
The 3 meter test was SO far over I suspected I received a Canadian model, but there's no way to tell apparently.
TIB
Rich....that transmitter has no power adjustment...is fixed, power adjustment was disabled with the CM-10. but the MS100 does.
Fasinated by the results.....maybe Michael at Decade should see this! You are correct the Canadian BETS-1 rule is 100uV/M @ 30 meters. Not drastically over but over just the same.
Appriciate you doing these very informative tests!
But for all of us that don't have this meter, the certification is what we have to go by.
Mark
My prediction. Either
1) We won't hear any more about the proposed testing with NYC engineers, or
2) A claim will be made that it has been done, but the details won't be revealed, just blanket statements. After all, why change what has worked in the past?
The Decade has been sold and shipped. So no more testing.
I'll keep the Potomac loaded and ready in case something else comes along to test before the snow flies, maybe a couple weeks at best unless this is an unusual year.
As the CM-10 is being discontinued, I don't see my buying their current Part 15 FM stereo transmitter which would be the MS-100S that is $575.00. Assuming it's legal I can't imagine it being worth that kind of money for the limited range of Part 15 FM. At least not for any purpose I would ever have.
I never did put the CM-10 on the spectrum analyzer to see how clean the signal was. Guess it just didn't seem to matter at those power levels.
So what else is current and inexpensive for testing 🙂
TIB
SainSonic AX-05B at -48dbm and the 500 mW level. Its $55 at the SainSonic websie:
When I ordered it using my Netspend card it took about a week or so and will be shiped from China. I want to know too what it looks like on a spectrum analyzer too. I'd like to see both power levels tested.
Signstek CZE-T200 from Amazon for $40
This has 4 power levels and looks like the low setting could meet part 15 although its not certified. I'd like to see this one compared with the SainSonic as it may be cleaner than the SainSonic transmitter as well. It runs on betteries and electric and can run on a cigarette lighter adapter as well. It does come with patch cords too.
I'd like to see some of the other ones like the Scoche transmitter which has an LCD desplay and can connect to any 1/8 inch patch cord. Carl had one that went 150 feet so I'd like to see some of those tested to see if we can find one that does have 250 uV/M @ 3 meters to compare the range. We still don't know how far a legal FM Transmitter can go in the real world so it would be interesting to see a 100% legal one if possible. Just some ideas.
I would be very interested in seeing a BroadcastVision certified FM transmitter tested. They can often be picked up on e-bay (used or new) for $50 to $100.
I'm not sure it's worthwhile testing any of the non certified Chinese transmitters - we've seen that even a certified one does (and it wasn't pretty).
The C Crane II would be another interesting one to test. I haven't seen too many of these on e-bay.
But perhaps you've done enough for now, Tim. You've spent money and done some great work. We certainly appreciate it here, but you've gotten nothing but grief from that other site. Why not let them have a shot at the testing and see what they come up with?
I may be moving on from my Decade MS100 in the next few months (I'm experimenting with AM once again), and if I do, I could certainly lend you that transmitter to test out (perhaps next spring). It is Canadian tuned, however.
I'm not trying to act ugly here so please forgive what I'm about to say. WHO CARES what that other site says. They can say this about data and that about data but if they don't want to present the data makes you wonder what their intentions are in the first place. I'd be really cautious of any site that claims a TX is legal or good without the data behind their tests. These tests were done and videotaped although the original field test was not but still shows good faith that everything was in good standing as far as how the test was conducted. The only thing I wish was that Tim had done a spectrum analysis of the harmonic and spurs that may be generated by this modified Chinese transmitter which is really no more than the same thing as the SainSonic. Yes SainSonic may have cheated a little however if the Decade has spurs or harmonics over the top than you can bet the SainSonic would as well and the other way around. So if he felt inclined to spectrum analyze the SainSonic we'd know what the Decade would do in the first place. I I don't subscribe to the thought that every Chinese transmitter is the same that is like saying every American Car is the same. I still think even if a transmitter is not certified and does better than a certified unit and you can get it into the legal realm via tests with a Potomac FIM 71 and a spectrum analyzer we still ought to look at these as well. I wish I had the money to try the Whole House FM transmitter 3.0 and see if I get less spurs at the 10 foot range. With the Grundig I can get the signal in the Shortwave band around 2 Mhz. Not good. If I had the Whole House 3.0 would that be more clean than the SainSonic? I'll never know. I just hope I can win the Whole House 3.0 and then I'll compare it myself. I'd also do a video on the spurs and harmonics below the FM band and in the band itself. If you live in a duplex it is even more important to individuals. Your neighbors would complain if your coming in on multiple spots on the dial and that will equal a NOUO.