My opinion-
If this is treated right, it could be a service similar to what New Zealand offers for their version of 'Part 15 FM". Not quite 500mW, but a step in the similar and right direction...
First to the Crow, thanks for the info on the
two 87.9 MHz licenses. I find that to be
really interesting. Interesting especially in
the fact that while class D was being phased
out (and sometimes I miss all those little 10 watt
FM stations) there weren't a few more stations
that went down to 87.9. When I got my first
fairly decent FM tuner and roof antenna in
1975, I heard quite a few of those little stations.
I would call them on the phone and the people
on the air would always be surprised that
there was somebody listening far away. (Far
away meaning 20 or 30 miles.) Unlike some FM
DXers in the 1970s, who heard 10 watters hundreds
or even a thousand miles away, I never had that
kind of luck. But to me, 30 miles was still a good
catch.
And to tbone903, thank you also for the detailed
explanation about Part 74 relating to Part 15
with regard to this new communication from the FCC.
It's early in the morning here in Connecticut. I'm
going to have to read your post a few more times
and really take it in. By the way, the vacuum tube
graphic you have next to your text reminds me of
my first Part 15 transmitter, which used a 35W4
and a 12BE6 on the AM band in 1968. Somewhere
around here on the Part 15.Us board, there is
another thread where we shared stories about
those old transmitters.
Thanks again guys!
Bruce, MICRO1690/1700
As far as I am concerned, this is a step in the right direction.
The fm band is so congested here in Ky that even the channel I operate on is noisy when conditions are just right.
Two other station's on 95.7 fm are 100 + miles from my location, one is in Tennessee and the other is licensed for Louisville but located on the Indiana, Kentucky border. Both stations give me trouble when tropo waves kick in. One other station WHIO 95.7 Dayton occasionally pop's up from time to time which is a treat since I am a Buckeye and miss home.
Even radio-locator.com has it's flaws. When it says there are vacant channels in London,Ky they really aren't that vacant when you factor in the weather conditions, my location and overlapping signals, the fm band is a real challenge for any fm station.
I would gladly save up some money for a transmitter to use in the tv band just to get out of the noise here in London.
If you own a Comtek BST-25.
So what kind of range would one expect from a device like the Comtek BST-25? I realize it has a bit more power than most fm devices used on 88 - 108 mhz. Seems like there wouldn't be listeners since it calls for a special receiver.
I wonder if it can be heard on analog t.v. sets?
For some reason i can't seem to get rid of a color t.v. I have here.
I don't really watch t.v. much myself , unless it is Sy-Fy channel and even then I have to fight someone for the remote lol.
I guess what i am looking for is a way to escape the crowded am/fm bands where I live, I still haven't messed with shortwave yet which is another option for me.
Has already filed objections to this NPRM
Hi There:
I noticed Rock95Seven"s comments.
The Comtek transmitter goes up as high
as 87.7. Lot's of FM radios tune there. 50
mW out to a 6 DB gain antenna is 100 mW.
With the Comtek,
I think an external antenna up high would give
practical neighborhood coverage, like several blocks, into
good home radios. You could probably get it a mile
away on a car radio. A lot would depend on
terrain and antenna height.
Contrast this with 250 uV per meter @ 3 meters
- or Part 15.239, which is what our FM transmitters
use now. There is some calculator on the internet
somewhere that says that the output power to
make that field intensity is something like 11 nanowatts.
(I believe that's the figure.) But this formula is for
a theoretical antenna sitting in theoretical space. We
all know that the Part 15.239 transmitters don't go
very far, and that has been discussed at length on this
board.
Still, it's a big difference between the two.
Carl mentions hearing a local LPTV on channel 7.
There are still a lot of LPTVs on the air. If you
have an LPTV or regular TV station on channel
6 you cannot operate the Comtek in that
channel.
My shortwave experiments have only worked out
to about 1000 feet from my house, but my SW
transmitter is not anywhere near optimized. That's
all on another thread here.
It's really fun to speculate on this TV channel FM
transmitter thing. I guess we'll just see what
happens.
Best Wishes,
Bruce, MICRO1690/1700
Hi MICRO1700
We still don't know how much of the shortwave thread was lost in the server failure, so I will sidestep from Comtek just once by saying that it sounds to me like maybe your shortwave transmitter at this time is either not up to full allowed power or maybe doesn't have an ideal antenna. What time of day was it when you got 1000-feet?
Some of the Comtek frequencies are expressly described as being for FM band, those lower channels, 87.5 etc.
As for TV audio the C.Crane Radio Plus I have a digitally tunable VHF audio band, Channels 2 - 13.
There are also other radios out there with TV band audio.
We have (nearby) TV channel 7 still going strong with I think 100 watts.
Tuning an analog TV I've noticed that other low power VHF stations are still operating.
This probably would not work, because analog TV's need a video sync pulse to lock to, in order to demodulate the audio at 4.5 Mhz above the video carrier. Even if it did demodulate the audio, it would probably sound distorted, because TVs are set up for 25 khz deviation, the standard for TV audio. By contrast, an FM station is 75 khz deviation. This is why each FM channel is 200 khz wide...75 khz upper and lower of the carrier, with 25 khz on each side as a buffer to help prevent interference to 1st adjacent channels on either side. Actually, 100% modulation equals 75 khz deviation.
One FM station in my town, modulates at 120%. I know this, because I have a TV transmitter in the same shack. They do run an RDS sub, so legally they could run 102%. Not sure how they get away with it....
I'll just respond briefly because there is
another thread for this.
My shortwave transmitter isn't putting out
any power. I am working on an tunable
RF output transformer for it. Also, I have
been mainly working on the Gates board.
I posted some stuff about that on the
vintage thread. I can update the SW stuff
on the SW thread and will do that soon.
Some of that thread has not been recovered
but a lot of it is there.
Now, onto this thread. My Part 15 station is
made from a lot of old stuff that is either homemade
or given to me. In order to get the Comtek transmitter,
I would have to sell all the other parts of my station!
Best Wishes!
Bruce, MICRO1690/1700
Bruce
I'm in the same boat you are i think.
I don't think it would be possible for me to purchase a Comtek transmitter without breaking the bank.
And i'm almost certain my wife would kill me. (figure of speech)
She might not physically harm me but that look she gives me when I am being a bonehead would be enough for me to come to my senses real fast lol.
Joking aside, this new section of Part 15 is alright if your willing to put that much money into a transmitter just for a hobby.
It really isn't for everybody in my opinion.
Perhaps it would do well as a STL setup with a directional antenna or something with a few db's of gain. For me, it just isn't do-able.
Hi Rock95Seven:
It's 7:52 AM here in Connecticut, I'm not
completely awake here, and I'm laughing
out loud at your post. I'm married too so
I'm completely with you there. From her
point of view, I'm more of a lunkhead, than
a bonehead.
Maybe somebody else out there in the Part 15
community will get one of these Comtek transmitters
and then we can all see how it does. If they put
the transmitting antenna up on a tower it would
be very interesting. There is a member on this
board from Canada who uses a different FM transmitter -
the Decade -
under the Canadian rules. He is allowed to run more
output than our Part 15.239 - I think the Decade can legally
run about a milliwatt of power output in Canada.
On paper, this is still a lot
more than our 250 uV/M @ 3 M. I think the antenna is self
contained on the transmitter. The Decade is expensive
but it is built like a tank and he is very happy with it.
I believe the Decade is up on his roof in a water tight
container.
If you buy a Decade transmitter for use in the U.S.,
it is set to run under our rules, which are less than our
friend in Canada is permitted - i.e., Part 15.239 for us.
As for the Comtek, it would be at least fifty times
more powerful than the Decade (Canadian version)
and several thousand
times more powerful than our certified FM transmitters
here in the U.S. Still, at these low power levels you
would have to have the Comtek antenna up high.
Some radios are better than others. The clock radio
in my bedroom doesn't even get most of the local
REAL FM stations.
I could see myself saving up for
one over a very very long period of time. I'm into
this Part 15 thing for the long haul. Now, it's back
to the Gates board restoration for me.
Thanks for the humorous post. It was a really good
start for my Friday!
Best Wishes
Bruce, MICRO1690/1700
Just a quick correction to the last post. In Canada, just as in the U.S., we're not measured (at least on FM) by output power (or input power) but allowable field strength. We're legally allowed 4 times the field strength allowed in the U.S. - 1000 uv/m at 3 meters (or, as our regulations put it, 100uv/m at 30 meters). Decade themselves confuses the issue by advertising their transmitters as having 1 mw output (but that's just the maximum it can do). They deliver the transmitter trimmed to the proper field strength for either the U.S. and Canada, based on where it will be used. As I've found with experience, with the increased field strength allowed in Canada, you can get about 1 km range if you have direct line of sight to your antenna (with no obstructions) to a sensitive car receiver.
I only mention this because I keep on reading about how much output power FM transmitters are allowed to be legal, in Canada and the U.S. - I've even gotten e-mails about it - and that's just not accurate.
Thanks ArtisanRadio for clearing that up.
I was specifically thinking of your station
when I made that post. And the explanation
about the Decade eliminates the confusion
I had.
Best Wishes
Bruce, MICRO1690/1700