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New LPAM Antenna

The new LPAM antenna is designed to improve the performance of part 15 AM transmitters, the 50 ohm antenna will require a matching transformer to mate with the Rangemaster, and some others.

Here are the results of early testing.

100foot 500’ 1000’ 1/2mile 1mile
10’3/4’ copper pipe 198uV (+10db) 33uV(S5) 0 0 0

New Antenna 8mV(+35db) 3.5mV(+30db) .31mV (+12db) 100uV (s9) (s7)

More information and pictures will be posted on the updated Radio Brandy Part 15 AM site, soon.


Steve
www.RadioBrandy.com
 
XRQKFM said:
The new LPAM antenna is designed to improve the performance of part 15 AM transmitters, the 50 ohm antenna will require a matching transformer to mate with the Rangemaster, and some others. ... More information and pictures will be posted on the updated Radio Brandy Part 15 AM site, soon.

Could you please comment further on the configuration of this new LPAM antenna system? For example:

(1) At what elevation above the earth is the base of this new antenna installed, and

(2) What is the length of the "new" radiator, and

(3) What is the total length of the conducting path from the transmitter chassis "ground" connection to whatever serves as the r-f ground for the tx + antenna system, and

(4) Were the field strength values in your post based on the same installation and operating conditions for the "new" system as for the "old" system?

//
 
Were the field strength values in your post based on the same installation and operating conditions for the "new" system as for the "old" system?

Side by side Proof of Performance tests were done with a 3/4”copper pipe 10’ long, and this antenna. The antennas were excited by a Motorola communications service monitor with 100 milliwatts out (through an amplifier). Measurements were taken with an A.R.A. RAM 220-b calibrated active antenna and an arbitrary calibrated signal probe (Protek hand held spectrum analyzer and a Kenwood receiver).
Both antennas were mounted to the same push-up with the same ground system.

Make no mistake! R.Fry a former RCA broadcast engineer, (NAB Member) is strongly opposed to community broadcasting of any kind. He spends most of his time trolling and posting on radio boards like this one and Ramsey's and Part 15 Us, putting the fear of law and discourage community broadcasting.

I can't believe R.Fry spends so much of his time & energy sweating over a few milliwatts, when community broadcasting is all about serving in the public interest, and providing innovate programming.

Could you imagine the public outcry if the FCC started pouncing on radio stations with a 100 milliwatts or less, while ignoring the blatant violations of full power broadcasters. Considering the large number of micro powered radio stations on the air across the nation; both AM & FM, it's obvious these radio stations are being responsible and not causing interference, while providing a community service.

Details on the antenna will be posted when testing is completed

Steve
www.RadioBrandy.com
 
XRQKFM said:
...Make no mistake! R.Fry a former RCA broadcast engineer, (NAB Member) is strongly opposed to community broadcasting of any kind.

There is no valid reason to object to any use of unlicensed systems meeting Part 15, and I do not.

These systems are low powered, but that doesn't mean that their operation is technically simple, or easily understood. This has resulted in a large amount of public supposition on this subject, which can lead users into potential problems with the FCC.

The goal of my posts is to provide accurate technical information about systems that actually meet Part 15.

I understand that whatever people do with that information clearly is up to them.

//
 
I do not believe Mr Fry's intent is opposition of any kind.

He is only reminding us that there is no free lunch, and what seems to good to be true should be examined thoughtfully.

I would venture there are many unexplored methods which should be left up to individual ingenuity,
which is why this new antenna may work as well as stated. Aspects unmentioned by rules are certainly game for experimentation.
Read the rules like a lawyer, and I'm sure you'll see some wiggle room, like there's no limit on positive modulation peaks..
Do not discount the value of high-level audio and limiting/compression to be worth as much as doubling in RF power.

I went to the old school, just like Mr Fry. He sounds like my instructors, so I know he is right.
He is part of the old time engineering school that will not depart from science and fact proven by performance and experience.
His integrity insists on helping all undestand the underlying engineering concerns of these matters accurately.
I would be saying the same things as he is, and I was part of an earlier flare-up regarding ground lead radiation.
I recommend basement-wall mounting at grade-level, with antenna immediately outside, but only because that is easy for me.
The floor of the garage might also be good.
I have to think an elevated MW stick for AM pt 15 has as much to gain by elevation line-of-sight as it has to lose by removal away from earth as conductor of the ground wave, presuming RF is choked off the ground. It's a wash, but is worth trying as every situation is unique.
I don't think you'd ever notice this effect at broadcast powers, but at micropower a "clear path" may be worth something.
My ground-based antenna has lots of lobes and cutouts in coverage I must assume are signal absorbtion on straight paths.
I will oneday test an elevated /RF choked ground antenna and see how it works in my dense city neighborhood.
 
Trust me a ground level antenna in an urban neighbor hood is really just an awful setup.
The signal jumps around everywhere but its blocked by the buildings surrounding you.
 
The new antenna has arrived at our new test facility, we are waiting for a transmitter with a 50 ohm output to arrive, before testing can begin. I can tell you the antenna is built like a rock, and unique in design. We will


Steve
www.radiobrandy.com
 
Make no mistake! R.Fry a former RCA broadcast engineer, (NAB Member) is strongly opposed to community broadcasting of any kind. He spends most of his time trolling and posting on radio boards like this one and Ramsey's and Part 15 Us, putting the fear of law and discourage community broadcasting.
I know this is an old thread. But anyone seriously researching Part 15 transmitters would like to hear what R. Fry has to say. Boosterism is fine. But I don't need a "boost", I'm already looking into it. I need relevant technical / regulatory information.
 
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