The last 49mHz website we linked turned out to be defunct, but now we are informed of new action from our radio friend Tha Dood in West Virginia
http://groups.yahoo.com/group/49_MHz/
The last 49mHz website we linked turned out to be defunct, but now we are informed of new action from our radio friend Tha Dood in West Virginia
http://groups.yahoo.com/group/49_MHz/
Great SH STL
Part 15 49Mhz makes a great Short Haul STL link..even for stereo operation by simply adding a stereo encoder to the TX and stereo decoder for the RX and a little bandwidth modifying on both. Used to use 49Mhz for STL purposes to feed audio from the studio to the very first 219 system set up on the opposite end of the mobile home. At that time, the 219 setup ran C-QUAM as well.
RFB
what kind of range can maxed
what kind of range can maxed power legal part 15 get at 49mHz? I am debating these 5.8 units I have… they are very very line of site. I bet 49mHz would better there…
49 MHZ
49 mhz can run up to a watt cant it?
The Rules for 49 mHz
FCC 15.229 — Operation within the band 40.66 – 40.70 MHz
(a) … the field strength of any emissions within this band shall not exceed 1,000 microvolts/meter at 3 meters.
FCC 15.231 — Periodic operation in the band 40.66 – 40.70 MHz
(a) …alarm systems, door openers, remote switches, etc.
FCC 15.233 — Operation within the bands 43.71-44.49, 46.60-46.98, 48.75-49.51 and 49.66-50.0 MHz
(a) …restricted to cordless telephones…
FCC Part 15.235 — Operation within the band 49.82 – 49.90 MHz
15.231 offers possibilities for certain remote control functions.
(a) The field strength of any emission within this band shall not exceed 10,000 microvolts/meter at 3 meters.
EDITOR’S COMMENTS:
Looking at the entire 40mHz spectrum is interesting, because it shows why Part 15.235, 49mHz, is especially significant for its increased power allowance. It appears to share space with some cordless phone channels.
Days on the 40mHz Spectrum
The ALINCO DX-X3 Communications Receiver is able to scan the 40mHz band in 1kHz increments, which I have been doing for several days. There has not been one trace of activity, not even outdoors at a high location.
I thought perhaps there might be some cordless phone calls going on or perhaps some other types of services, as only slivers of the spectrum are parceled for part 15 activity.
I will be banging on a few doors to start a workshop on whether the Big Talker Shortwave Transmitter, itself designed for 13.560mHz, can perhaps have a version tailored for 49mHz operation; more specifically 49.860mHz.
If such a transmitter were available, the next question would be coming up with an appropriate receiver, as perhaps this might be a useful channel for STL (studio-transmitter-link).
Comment line is open.
Over the Top
On today’s Blare OnAir Lite No. 19, titled “49 Megan Hurts” I ramble a little bit about emerging plans to modify the Big Talker Shortwave Transmitter for use on 49mHz.
The idea is to build it first and come up with a reason later.
http://kdxradio.com/blare_lite.html
Hi : A few comments and a question
Although most of what I am going to say
is about 49 MHz, I did have a question:
Carl – about the Blare OnAir Lite Show:
Are you just streaming it? If so, what time
of day is it on? I was unable to locate it
on your website, and I really want to hear it.
Back to 49 MHz: I looked at the 49 MHz site
with great interest. 49H7KR sounds like
the 49 MHz “callsigns” of the past.
The five channel 49 MHz walkie talkie which
is shown in the photograph (Radio Shack TRC-503)
on the site was
once of great interest to me. I only had the
one channel version. At that time, the 49 MHz
5 channel walkie talkie was about $35.00, and
I should have just bought two of them at the
time. At the time I felt I couldn’t justify the money,
but I wish I had. It would have been possible to
get a clear frequency on one of these radios,
away from the baby monitors and cordless phones,
because of the 5 selectable channels. The receivers
were very hot, and even though the rigs only ran
about 10 mW (I think) you probably could have done
some real communicating. I got my 1 channel Radio
Shack TRC-501 to go between 1/3 to 1/2 mile, when
the channel was clear.
I am confused about the rules that say you can
build a “100mW DC input to the final” transmitter
that is legal under Part 15, but I haven’t had time
to check the rules, so I could be way off about that one.
I do have a 49 MHz link set-up here. It works fine and
will transmit and deliver line audio to a 49.83 MHz receiver, but
it is kind of a mess. It was made from two 49 MHz
walkie talkies, and the circuit boards are not really
in very good enclosures.
In order to hear signals on the 30 to 50 MHz band, you
need two things.
1) Well, I think anyway – you really need a good antenna,
preferably outside and up some distance – maybe on
your roof or on a mast or maybe in a tree, but it
has to be BIG, have some gain, and it must be outside.
2) Good propagation is a big deal for this range.
In the fall of 1981, I heard (I presume) South and Central America
all over the place on the whole range. The F2 skip
was pounding in them. 6 meters (50 MHz) was open
to California from my Connecticut location. It was exciting.
Later on, in the 1989 to 1991 timeframe, a lot of afternoons, I would
get a sporting match from somewhere on 46 MHz. It was
either audio from a TV channel (which I doubt) or some kind
of STL, or remote cueing system. Where ever it was, it was
not nearby, I know that. Maybe it was in Europe, but it
could have been somewhere else.
There should be F2 skip in the 30 to 50 MHz range occurring about
this time of year, but there is not. This sunspot cycle should be
way up, but it is not. Sometimes 10 meters has been open
(28.000 – 29.700 MHz,) though, but I have not heard of the
maximum usable frequency going up much beyond that.
Sunspot cycle 24, which we are in right now, is just a bust.
I understand the F skip got up to 50 MHz about a year ago,
but so far, it has not come around again.
Very very interesting stuff.
Bruce, W 60 HZ, etc.
Right This Way Sir
Hi Bruce!
My last post above has a link, but I’ll also link it here, to the Blare OnAir programs, which are mp3 audio downloads.
Today I added No. 20, a Christmas Card for all part 15 stations worldwide, of which none exist outside the U.S. and perhaps its possessions and territories.
http://www.kdxradio.com/blare_lite.html
49mHz on the Mind
Tha Dood in West Virginia is doing some very interesting things with 49mHz, which will be covered on the LPH.
Meanwhile I got to wondering what the rules say about antennas for 49mHz.
15.235 — Operation in band 49.82 – 49.90mHz
(3) The antenna shall be a single element, one meter or less in length, permanently mounted on the enclosure containing the device.
That’s easy.
And here’s a section that took a moment to ponder…
(2) The total input power to the device measured at the battery or the power line terminals shall not exceed 100 milliwatts under any condition of modulation.
“m” vs. “M”
A gentle reminder — for SI units the “m” prefix is a modifier meaning 1/1,000th of the units that follow.
The “M” prefix is a modifier meaning 1,000,000 times the units that follow.
So a frequency of 49mHz = 0.049 Hz, while a frequency of 49MHz = 49,000,000 Hz.
Big difference.
I Just Thought
In my sketchy view of life I thought the main thing was to capitalize the H with respect to Heinrich Hertz, inventor of frequency.
The “m” was simply a jotty figure for “mega”.
But, now, with this new information, what can I do but return to school.
So is anyone actually USING 49MHz?
I anyone using 49MHz for naything, such as STL purposes? I posted a few days about using Part 15 FM as a link between my studio and City Hall, where my audio feeds into the local cable system as background on the public access channel. I have an AM receiver there now, picking up my AM signal, and there’s a ton of signal strength from me there to be received, but also a ton of interference from computers, TV sets, cable equipment, and the like. I’ve got it “passible” but a long way from what I consider acceptable. Pparently FM Part 15 doesn’t have the guts to get a signal 450 feet line of sight (there’s nothing between my antenna and the City Hall office window. I don’t want to invest in an FM transmitter to find it won’t work.
However, while digging around in the basement looking for something else, I ran across a toy radio “base station” I picked up along the way. It operates on 49 MHz. It takes 6 “D” batteries. Short version: I hooked it up in the attic, set up some sort of old VHF radio at city hall (I don’t remember what it was, small, silver, slide rule dial, metal, something like 30 – 130 MHz coverage in a couple bands). It received the base station loud and clear with no interference, etc. So, I’m wondering about a bit more of a “permanent” experiment. Anyone using 49 MHz?
Tim in Bovey
Hello Bovey
Tim, I have some e-mails from Tha Dood, a part 15 guy in Poca, West Virginia, about how he is or has used 49MHz as an S.T.L. for his station. I still plan to do a Low Power Hour with Dood on this and other topics, but right now he is busy with contaminated water affecting 300,000 people because of a chemical accident.
Also, we have the schematic all drafted for 13.560MHz which could be easily shifted up to 49MHz.
http://kdxradio.com/bigtalker.html
40 mhz band in Europe
In the EU there is a legal 100mW 40 mhz band 40.665/40.680/40.695 covered by the Busch walkie talkies (one for the upper and lower frequenciess, another for 40.680).