Bruce Micro Dog, that was just getting interesting.
We're here waiting for the next part.
In the summer of 2003, a Northern
Ireland FM DXer heard WHCF, Bangor,
Maine, via multihop E-skip across the
Atlantic ocean. This comes out to
2710 miles. I have also heard WHCF
at my house here in Hartford, CT. WHCF
is 291 miles away from me. I have some
very low noise receivers for the FM BCB,
and have had some good antennas for DX.
If you can hear random FM stations skipping
off of meteor trails in the morning (that's
the best time of day to listen) then you
know that your set-up is working pretty well.
A rotatable antenna is a must.
And what does this have to do with
Part 15 FM??? Well, back in my notes
somewhere buried under a pile of stuff
are some examples of when FM DXers
heard very weak FM signals. You know -
like a Mr. Microphone 1/2 mile away, or
something like that.
If I have told this story before -
well - my memory is going down
the drain... I'm getting older faster
and faster.
Bruce, Dogs and... and... uh... Radios
P.S. Once I saw a picture of the
Ireland DXer's receiving set-up.
He had multiple stacked log
periodics on a tower. And
then more of them. It was
unbeleivable.
I used to live in southern Utah in the 80's. While camping up in the mountains, I used to tune in a station in Albuquerque - which was right at 250 air miles away.
It was strong enough to have a solid stereo sound and sound decent.
I had a car radio with an FM reception booster.
250 miles, that's cool!
FM DXing, ya gotta love it!
Bruce,
The Dog Radio Group
To continue use of our Part 15 FM systems for studio-to-transmitter linkages, we are reducing the field strengths to the lowest possible and leaving it to the FM receivers to compensate by designing sensitive antennas.
This morning we tested the C.Crane FM transmitter at the lowest possible antenna height, which is 3" vertical. The FM tuner is only 1.5' away with its antenna fully collapsed, and receives a full signal with no dropouts. The spectrum analyzer, located 8' away, shows a reading of 50dBm.
To compare, with the FM transmitter telescopic antenna fully extended to 11" the spectrum reading is 57 dBm.
Later today we will see what the dBu readings are down by the street, using the TECSUN PL-310.
The C.Crane FM channel is used for audio editing, and achieves a wireless monitor speaker (the radio) for the purpose.
There are two other FM transmitters yet to be "crippled" so they do not embarrass the family.
The Wholehouse 2.0 is attached to a 1/2Wave antenna, but which was tuned to a slightly higher frequency than the frequency being used. It's reading on the spectrum analyzer is 51dBm, just a hair higher than the C.Crane FM transmitter with antenna at minimum (3").
By unclipping the Wholehouse from the 1/2Wave antenna, leaving only the original 3" stub of wire, the spectrum reading drops to 50dBm.
The Wholehouse is 5' farther from the spectrum analyzer than the C.Crane.
I had previously discovered that adding antenna length to the Wholehouse has a very small effect, from which I guess that Wholehouse inserted an RF ouput capacitor with very little signal getting to the other side.
The formula for measuring a 1/2Wave antenna is included with the certified Wholehouse, with no warning such as "Not for use in the U.S.", but as we've found, such an antenna does little to enhance performance.
The Wholehouse 2.0 is attached to a 1/2Wave antenna, but which was tuned to a slightly higher frequency than the frequency being used. It's reading on the spectrum analyzer is 51dBm, just a hair higher than the C.Crane FM transmitter with antenna at minimum (3").
By unclipping the Wholehouse from the 1/2Wave antenna, leaving only the original 3" stub of wire, the spectrum reading drops to 50dBm.
The Wholehouse is 5' farther from the spectrum analyzer than the C.Crane.
I had previously discovered that adding antenna length to the Wholehouse has a very small effect, from which I guess that Wholehouse inserted an RF ouput capacitor with very little signal getting to the other side.
The formula for measuring a 1/2Wave antenna is included with the certified Wholehouse, with no warning such as "Not for use in the U.S.", but as we've found, such an antenna does little to enhance performance.
The Wholehouse 2.0 is attached to a 1/2Wave antenna, but which was tuned to a slightly higher frequency than the frequency being used. It's reading on the spectrum analyzer is 51dBm, just a hair higher than the C.Crane FM transmitter with antenna at minimum (3").
By unclipping the Wholehouse from the 1/2Wave antenna, leaving only the original 3" stub of wire, the spectrum reading drops to 50dBm.
The Wholehouse is 5' farther from the spectrum analyzer than the C.Crane.
I had previously discovered that adding antenna length to the Wholehouse has a very small effect, from which I guess that Wholehouse inserted an RF ouput capacitor with very little signal getting to the other side.
The formula for measuring a 1/2Wave antenna is included with the certified Wholehouse, with no warning such as "Not for use in the U.S.", but as we've found, such an antenna does little to enhance performance.
That last post ("Another Transmitter") repeated 3-times! My ENTER key must have a stutter.
In that post I took spectrum analyzer readings of two FM transmitters, a C.Crane and a Wholehouse 2.0, giving all the technical conditions used for the tests.
Today I took the TECSUN PL-310 radio outside for a look at field strength and signal-to-noise, the radio's antenna was vertical telescoped to min. 4.75"
Sitting on a porch step 30' away from the transmitters the C.Crane showed as 07dBu Signal Strength/06dB Signal-to-Noise.
The porch step reading for the Wholehouse 2.0 was 16dBu Signal Strength/16dBSignal-to-Noise.
Moving 100' down to the curb the C.Crane showed 00dBu Signal Strength/00dB Signal-to-Noise.
The Wholehouse 2.0 showed 01dBu Signal Strength/01dB Signal-to-Noise.
For comparison, a nearby 100kW station registered 62dBu/47dB.
Not too long ago a new translator FM came on 107.3mHz with 250 Watts, and being nearby on a tall tower it forced KDX-FM at 107.1mHz to search for a new frequency.
I like the top of the FM band because antenna lengths are shorter.
Using the spectrum analyzer and the geographic transmitter positions of the local FM stations, as shown at radio-locator.com, I chose spots that looked like "valleys" cut in the FM mountains, as viewed on the analyzer screen. The first trial took place on 106.1mHz, but the adjacent neighbors were more powerful and physically closer to us, so we then tried 105.3mHz, with the adjacent neighbors being weaker and farther away in distance.
But one of my receivers still got bleed-over from the high power stations nearby in frequency.
So I went lower until I found some very weak neighbors, but the remaining frequencies seem to be more scarce than ever before.
Then I noticed that besides an infusion of more translators, a large number of FM stations have CPs (construction permits) to significantly increase power.
I doubt that all the upgrading is a result of great commercial success, but rather suspect that stations are making a desperate bid to succeeed by expanding, which is probably a dangerous gamble.
Here in Vancouver there are virtually no unused FM frequencies. There are a few that are relatively quiet in some locations due to geography, but even they can be interfered with with powerful adjancent channels. I'm lucky that in my new location (on the water in English Bay), there are a few dead zones, including the frequency that I use (99.7). However, if I go up the hills away from the water, those channels are no longer dead. Luckily, the range for Part 15 FM (even in Canada) is sufficiently small that I don't have to worry about it.
Here in West Hartford, Connecticut - there are
a few empty FM cnannels, but I am in a valley.
At my parent's house in Jamestown, Rhode Island
(where you can see Providence and Boston) the
band is full. Do you guys remember FCC docket 80-90?
That was a ruling that allowed many more FM statons
to go on the air - about 20 years ago(???) The "new"
stations plunked themselves down in the "empty" spots
between the then existing stations. In other words,
the distance rules were relaxed. As an FM dxer, I
find it to be extremely annoying. Also, none of
the 80-90 stations were doing anything different
than the older FM stations. The programmng was
all the same old stuff.
Bruce, DOGRADIO
Once again the Dog Radio has said something.
"The same old stuff" is what bothers me, and I truly think, is what keeps radio from actually succeeding.
I hear imitations of the top 40 DJ style being copied over and over, with dazzling sound effects and punchy slogans, but that's not really of interest to a thinking adult person, i.e., "It's 98.7 The Splash! All Over You!" SFX: Shhhhwiishh!!
Can the station spokesman calm down, relax, and just talk to us? What are you saying, plain and simple? Never mind the stingers and promotional branding.
The formats that have become so conventional are really dull - "adult contemporary", "50s rock", "future mountain."
What if a human simply turned his microphone on and said, "Hello. My fictitious name is Rodney, and here's a record I have."
Are we still 6-years old?
If you can lay up a clean LOS space, I really like the idea of an optical beam. It won't carry any significant RF energy, so, although not Part 15, seems like a great way to send a wireless audio signal to a small constellation of FM transmitters. If all are identical and equidistant from the base station, I wonder if they could be sync'd well enough to be on the same frequency.
But, hey, even if not, it would still make for a nice multi-frequncy neighborhood station...if you are out in the hinterlands and have done your research on available frequencies.
I had plans for a single Part 15 repeater.
I think the chalenge is facinating.
I had a lot of the pieces, including a great
solar panel from a very generous person.
I think building the equipment is relatively
easy. Trying to convince somebody that
having your repeater on their property
is safe and legal - that's hard.
I know because I tried and failed. The project isn't
over, I'll keep chipping away at the concept
of the thing. In the meantime, the solar panel
from that nice person is being used to
power something else.
Bruce, DOGRADIO