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WNAR-AM 1620 Transtenna covers 6 miles!

Re: A question about grounds

> Rfry... you are the radio police here, please input
> your comments as well!
__________

No, I am not the radio police. My comments here are based on provable principles of radio engineering -- not on wishful thinking, hopes, and arbitrary, unproven beliefs.

I could not care less as to the tx power and/or antenna configurations that you and/or others believe is permitted by Part 15. Whatever you want to do has no penalty for me.

The purpose of my posts here, and on other forums, has been to try to give a rational, engineering-based perspective to readers of these forums.
//
 
Re: A question about grounds

> > Rfry... you are the radio police here, please input
> > your comments as well!
> __________
>
> No, I am not the radio police. My comments here are based
> on provable principles of radio engineering -- not on
> wishful thinking, hopes, and arbitrary, unproven beliefs.
>
> I could not care less as to the tx power and/or antenna
> configurations that you and/or others believe is permitted
> by Part 15. Whatever you want to do has no penalty for me.
>
> The purpose of my posts here, and on other forums, has been
> to try to give a rational, engineering-based perspective to
> readers of these forums.
> //
>


Then give your real perspective on what I commented above or do you only attack those outside the Rangemaster circle?

Radiopilot
 
Re: A question about grounds

> Then give your real perspective on what I commented above or
> do you only attack those outside the Rangemaster circle?
_________

I do not support or attack any specific Part 15 AM tx OEM. I comment only on the assumptions attributed to their use, by you and others.

//
 
Re: A question about grounds

> > Then give your real perspective on what I commented above
> or
> > do you only attack those outside the Rangemaster circle?
> _________
>
> I do not support or attack any specific Part 15 AM tx OEM.
> I comment only on the assumptions attributed to their use,
> by you and others.
>
> //
>



So for these assumptions, anyone using such a set up as posted on the Rangemaster site is not illegal in your eyes, but anyone posting on these and other boards using similar if not more legal installations are attacked by your assumptions?

We would not be having these types of posts here on these boards if the only comments coming from you were positive, well meaning posts, even if you had to bite your lip when writing them, because somehow you may not agree to them, it wasn't yours to comment on since people will do as they wish regardless!

Radiopilot
 
Radiopilot does this look legal?

Hi,

I did not intend to restart this legal ground debate, but I guess I did.

My answer your question:

"> Neil,
>
> Take a look at this diagram from Rangemaster and look
> carefully at the tower and it's ground lead to the radials
> or ground rod... Does this look legal?
>
> http://www.am1000rangemaster.com/hints.pdf
> http://www.am1000rangemaster.com/elradial.pdf
>"

No. It does not look legal and that is just my opinion.

My interest in the statement by SuperSound was its orgin. It may be "official" but it is not mentioned in the part15 rules. One thing that caught my attention is the distinction between a preexisting structure used for other purposes and one constructed specifically for part15 AM. I can't understand why, if both enhance the radiation, that based on time one is legal and the other not. This statement itself implies that a tower constructed for part15 AM and forming the ground system is not legal. Otherwise, why make the distinction between this and preexisting and other uses.

I have read the posts about the Rangemaster setup being OK with FCC inspectors and that is fine with me. It just isn't clearly stated in the law. You are correct with your statement:

"**** This rule says 3 meters total for the antenna and ground 'lead' if used...
This does not imply, what the attach point for the ground lead should be....".

There is no clear answer to this, just various interpretations. Mine is, right or wrong, ground is where the wire goes into the dirt.

Neil
 
Re: Radiopilot does this look legal?

> Hi,
>
> I did not intend to restart this legal ground debate, but I
> guess I did.
>
> My answer your question:
>
> "> Neil,
> >
> > Take a look at this diagram from Rangemaster and look
> > carefully at the tower and it's ground lead to the radials
>
> > or ground rod... Does this look legal?
> >
> > http://www.am1000rangemaster.com/hints.pdf
> > http://www.am1000rangemaster.com/elradial.pdf
> >"
>
> No. It does not look legal and that is just my opinion.
>
> My interest in the statement by SuperSound was its orgin.
> It may be "official" but it is not mentioned in the part15
> rules. One thing that caught my attention is the
> distinction between a preexisting structure used for other
> purposes and one constructed specifically for part15 AM. I
> can't understand why, if both enhance the radiation, that
> based on time one is legal and the other not. This
> statement itself implies that a tower constructed for part15
> AM and forming the ground system is not legal. Otherwise,
> why make the distinction between this and preexisting and
> other uses.
>
> I have read the posts about the Rangemaster setup being OK
> with FCC inspectors and that is fine with me. It just isn't
> clearly stated in the law. You are correct with your
> statement:
>
> "**** This rule says 3 meters total for the antenna and
> ground 'lead' if used...
> This does not imply, what the attach point for the ground
> lead should be....".
>
> There is no clear answer to this, just various
> interpretations. Mine is, right or wrong, ground is where
> the wire goes into the dirt.
>
> Neil
>

Neil,

Did not mean to strike a bad chord with anyone here...

The assumption is correct that a pre-existing structure is valid while a structure built for use as an elevated ground is not. the rules are pretty vauge in regards to this indeed!

The ground lead going into the dirt is fine if you live in an area to place such a ground, what do you say to the person on the 10 floor of an apartment building? Is that pipe on the side of building a ground that can be used, and would it be as legal? Isn't that a '100 foot ground lead' going into the dirt?

This is why the FCC intentionally left this out, and only suggested the 3 meters including a very short ground lead to 'attach' to a rod, pipe, metal structure, or whatever to complete the circuit!

The toy AM transmitters (Radio DJ, for example) that are FCC certified has a small alligator clip to attach to a pipe or other metal structure. Now the FCC knows for a fact that this lead is not going to be attached to some ground rod pounded 10 feet into the dirt or that the clip will attach to the pipe on the 10th floor of a building, etc. The FCC knew this so they left it out, this is something they could not regulate.

You can see why this has caused such turmoil.

Radiopilot
 
Re: Radiopilot does this look legal?

Hi Rick Radiopilot (right name I hope. I read it somewhere.),

Nice reply. No sore points for me, but some here get aggrivated when we get into discussing the rules, thus my reluctance to bring it up again.

My answer to your questions regarding folks in tall buildings, etc. would be based on my interpretation of the RF technology...ground is where the wire goes into the dirt. This is the most defendable statement that I can make concerning RF grounds because any conductor in the antenna system which is above ground becomes a radiator. I really don't know what the FCC considers ground for part15 AM.

The SSTRAN unit and other "phono oscillators" work very well without a ground as long as you are just trying to cover your home with limited range and if so the ground issue goes away.

Neil
 
Answers:
Expensive.
No.
Please see new WNAR-AM thread I have posted.
-Rich
> > What kind of costs do you have in an antenae that can
> cover
> > 6 miles? And are you exceeding any limits?
> >
> > >
> >
> > Here are pix of the WNAR-AM transtenna in Lansdale, PA
> that
> >
> > > covers 6 miles!
> > > Website is:
> > > www.wnar-am.com
> >
> > > Links to pix:
> > > http://www.wnar-am.com/images/1620 WITH FLAG.jpg
> > > http://www.wnar-am.com/images/1620.jpg
> > >
> >
>
>
> "The three WNAR transmitters are in compliance with 47 CFR
> 15.219."
>
> In the website above Dave states that he is using 3
> transmitters to achieve the 6 miles.... it's all legal from
> what I've read, Rfry may have a different answer though, he
> may think the flag pole is radiating more of the signal than
> the 3 meter antenna, but I'll let him state that!
>
> Radiopilot
>
 
Answers:
Expensive.
No.
Please see new WNAR-AM thread I have posted.
-Rich
> > What kind of costs do you have in an antenae that can
> cover
> > 6 miles? And are you exceeding any limits?
> >
> > >
> >
> > Here are pix of the WNAR-AM transtenna in Lansdale, PA
> that
> >
> > > covers 6 miles!
> > > Website is:
> > > www.wnar-am.com
> >
> > > Links to pix:
> > > http://www.wnar-am.com/images/1620 WITH FLAG.jpg
> > > http://www.wnar-am.com/images/1620.jpg
> > >
> >
>
>
> "The three WNAR transmitters are in compliance with 47 CFR
> 15.219."
>
> In the website above Dave states that he is using 3
> transmitters to achieve the 6 miles.... it's all legal from
> what I've read, Rfry may have a different answer though, he
> may think the flag pole is radiating more of the signal than
> the 3 meter antenna, but I'll let him state that!
>
> Radiopilot
>
 
> > > "The three WNAR transmitters are in compliance with 47
> CFR
> >
> > > 15.219."
> > >
> > > In the website above Dave states that he is using 3
> > > transmitters to achieve the 6 miles.... it's all legal
> > from
> > > what I've read, Rfry may have a different answer though,
>
> > he
> > > may think the flag pole is radiating more of the signal
> > than
> > > the 3 meter antenna, but I'll let him state that!
> > >
> > > Radiopilot
> > >
> >
> > If you look at that site more, I noticed he "Added" some
> > circuitry "After" the Rangemaster. Two notch filters and a
>
> > loading coil at the base of the antenna..
> >
> > http://www.wnar-am.com/images/1620 atu-2.jpg
> >
>
> This to me looks like a 'mod' to the Rangemaster... and as
> such should void the certification... if I were an FCC
> agent, this would be cause for a closer inspection and
> certification of type issue....
>
> Of course there is no need to 'modify' the SStran to get any
> further range as that is what the base loaded coil and
> antenna does alone without certification or grey areas....
>
> Radiopilot
>
Why would adding loading coils and antennas to the SStran transmitter, without new certification, be different then any adding them to any other transmitter?
The transmitter installation would have to be tested, measured, and certified.
According to Dave (WNAR-AM) the SStran has great audio modulation but a low efficiency output stage that reduces output and limits coverage.
 
> > > > "The three WNAR transmitters are in compliance with
> 47> CFR> > > > > 15.219." > > > > > > In the website above
> Dave states that he is using 3> > > transmitters to achieve
> the 6 miles.... it's all legal> > from> > > what I've read,
> Rfry may have a different answer though,> > > he> > > may
> think the flag pole is radiating more of the signal> > than>
> > > the 3 meter antenna, but I'll let him state that! > > >
> > > > Radiopilot> > > > > > > If you look at that site more,
> I noticed he "Added" some> > circuitry "After" the
> Rangemaster. Two notch filters and a> > > loading coil at
> the base of the antenna..> > > >
> http://www.wnar-am.com/images/1620%20atu-2.jpg> > > > This
> to me looks like a 'mod' to the Rangemaster... and as> such
> should void the certification... if I were an FCC> agent,
> this would be cause for a closer inspection and>
> certification of type issue.... > > Of course there is no
> need to 'modify' the SStran to get any> further range as
> that is what the base loaded coil and> antenna does alone
> without certification or grey areas....> > Radiopilot> It's
> kind of misleading to say that "this is the antenna (and
> then show it) that broadcasts 6 miles...only to find out
> that there are three $1,000 dollar transmitters involved in
> the operation..............look folks, here it is all over
> again....part 15am radio is like a walkie talkie...it's
> about the same power...just on a commercial frequency....if
> you are lucky to live in an area where you have a clear
> frequency (rare!) in the 1500-1700kHz band, you will have a
> pretty good range with any good part 15 AM transmitter and a
> matched antenna....as an example, I could take the best am
> transmitters and antennas, stick an installation in NYC
> (where there is virtually NO clear frequency and have a ton
> of trouble getting a good range. I could also do the same
> installation in sand and get about the same basically poor
> quality signal...Certified or not, the sum of the parts of
> these transmitters are all the same; the main difference is
> what you can afford to pay for them....There are give and
> takes for each system; it is up to a buyer to decide what is
> right for him....a ground rod is not exactly an excellent
> ground for an AM station, since the vast majority of an AM
> station's signal is indeed ground.....ground radials are the
> best installation in any AM installation....Height is cool
> with such low power, but again, you are taking the very same
> 102" antenna and either placing it high up, or low to the
> ground, close to it's radials.Which is better?..that seems
> to be the question of the year on this board........my
> opinion hasn't changed; if you want a plug/play transmitter,
> perhaps Rangemaster is the very best one; but it is costly
> and has about the same range as any other good part 15 AM
> transmitter. It costs more because getting certification
> costs a lot of money....the SSTRAN costs less because it is
> indeed a kit (one that can be built for you) and the antenna
> needs tuning...it is a lot more work than screwing in a CB
> antenna.....They are both great transmitters and they do the
> very same job...the difference is in cost and work involved
> in setting up the installation.Antenna Guy Carl
>
I agree with most of what you say with some small modifications.
Experimental evidence shows elevating the entire antenna above ground, reduces ground losses, so that a marginal ground system, introduces less loss. This is only logical since the induced current in the (soil) ground is less. The farther away from the antenna, the less loss. Local ground conductivity has a signnificant effect also. Seawater is much more conductive then rocky soil. Copper and silver are even more conductive then salten seawater. The more conductive, the less loss.
For plug and play use the SStran and Rangemaster both are good choices. The SStran has lower cost and good modulation, while the Rangemaster has a higher efficiency output stage, higher output, but also higher cost. Like most things in life, nature, or science, you don't get something for nothing.
Please note that WNAR-AM is not plug and play, and the modifications suggested are in no way reccomended for plug and play applications by amateurs at other locations.
 
> > > > > "The three WNAR transmitters are in compliance with
> > 47> CFR> > > > > 15.219." > > > > > > In the website above
>
> > Dave states that he is using 3> > > transmitters to
> achieve
> > the 6 miles.... it's all legal> > from> > > what I've
> read,
> > Rfry may have a different answer though,> > > he> > > may
> > think the flag pole is radiating more of the signal> >
> than>
> > > > the 3 meter antenna, but I'll let him state that! > >
> >
> > > > > Radiopilot> > > > > > > If you look at that site
> more,
> > I noticed he "Added" some> > circuitry "After" the
> > Rangemaster. Two notch filters and a> > > loading coil at
> > the base of the antenna..> > > >
> > http://www.wnar-am.com/images/1620%20atu-2.jpg> > > > This
>
> > to me looks like a 'mod' to the Rangemaster... and as>
> such
> > should void the certification... if I were an FCC> agent,
> > this would be cause for a closer inspection and>
> > certification of type issue.... > > Of course there is no
> > need to 'modify' the SStran to get any> further range as
> > that is what the base loaded coil and> antenna does alone
> > without certification or grey areas....> > Radiopilot>
> It's
> > kind of misleading to say that "this is the antenna (and
> > then show it) that broadcasts 6 miles...only to find out
> > that there are three $1,000 dollar transmitters involved
> in
> > the operation..............look folks, here it is all over
>
> > again....part 15am radio is like a walkie talkie...it's
> > about the same power...just on a commercial
> frequency....if
> > you are lucky to live in an area where you have a clear
> > frequency (rare!) in the 1500-1700kHz band, you will have
> a
> > pretty good range with any good part 15 AM transmitter and
> a
> > matched antenna....as an example, I could take the best am
>
> > transmitters and antennas, stick an installation in NYC
> > (where there is virtually NO clear frequency and have a
> ton
> > of trouble getting a good range. I could also do the same
>
> > installation in sand and get about the same basically poor
>
> > quality signal...Certified or not, the sum of the parts of
>
> > these transmitters are all the same; the main difference
> is
> > what you can afford to pay for them....There are give and
> > takes for each system; it is up to a buyer to decide what
> is
> > right for him....a ground rod is not exactly an excellent
> > ground for an AM station, since the vast majority of an AM
>
> > station's signal is indeed ground.....ground radials are
> the
> > best installation in any AM installation....Height is cool
>
> > with such low power, but again, you are taking the very
> same
> > 102" antenna and either placing it high up, or low to the
> > ground, close to it's radials.Which is better?..that seems
>
> > to be the question of the year on this board........my
> > opinion hasn't changed; if you want a plug/play
> transmitter,
> > perhaps Rangemaster is the very best one; but it is costly
>
> > and has about the same range as any other good part 15 AM
> > transmitter. It costs more because getting certification
> > costs a lot of money....the SSTRAN costs less because it
> is
> > indeed a kit (one that can be built for you) and the
> antenna
> > needs tuning...it is a lot more work than screwing in a CB
>
> > antenna.....They are both great transmitters and they do
> the
> > very same job...the difference is in cost and work
> involved
> > in setting up the installation.Antenna Guy Carl
> >
> How can you prove to an FCC agent that the SSTran is indeed
> operating at 100 milliwatts? In an email communication I had
> with its designer, he stated there is no easy way to verify
> that its input is at 100 milliwatts, other than taking his
> word for it.
>
The SStran has an output stage limited to 100 milliwatts input. The fidelity of the SStran is good, but the disadvantage is that final amplifier efficiency and power output are not as high as the Rangemaster. Chevy or Farrarri both are transportation, and both have advantages and disadvantages.
 
> > How are you to prove to him that the power to the
> > Rangemaster is indeed 100mw also? It is assumed that the
> > designer of the SStran and of the Rangemaster has taken
> the
> > proper steps to insure the transmitter is in compliance to
>
> > the part15 100mw rule. Now you can measure the current and
>
> > the resistance of the transmitter and derive the power
> > out... this is simple Ohms' law... P=I^2*R or P=I*E.... No
>
> > different if you 'homebrewed' the transmitter and had to
> > show compliance of the 100mw power out.
> >
> > But we are not talking about the SStran here, but rather
> the
> > above reference to the photo of what shows the Rangemaster
>
> > being 'modified' therefore voiding it's certification, and
>
> > no one 'noticed' it? But if you go to the Rangemaster
> > website it complains about 'kits' being illegal when the
> > reference is for 'TV interface kits'.....Why?
> >
> > Radiopilot
> >
> The Rangemaster has a procedure for using a multimeter to
> set the input to 100 mW. I use a "homebrewed" transmitter
> which is constantly metered (volts and current), and I have
> documented the accuracy of the meters I use. Keith Hamilton
> has told me that remote metering can also be done with the
> Rangemaster. The SSTran apparently has no such option. One
> would think if you have a metering panel in your studio
> displaying TX input parameters, you would be further ahead
> than simply stating to the FCC that your kit's designer says
> that your unit has an input of 100 mW, but you have no way
> to monitor or adjust it. At the very least, the Rangemaster
> offers the ability to show (with a multimeter) that it is
> indeed inputting 100 mW.
>
> The rules do not specify output power, only input power,
> thus P=I^2*R has no relevance to Part 15, only E*I of the
> final amp is applicable. You do not measure the "resistance
> of the transmitter and derive the power out..." Measuring
> the radiation resistance of an antenna is a very complex
> procedure, involving several thousand dollars worth of
> equipment (impedance bridge, generator, detector, etc).
>
> By the way, I agree the Rangemaster in the photo appears to
> have had its approval voided.
>
I agree with the last 3 paragraphs.
WNAR-AM is not a "plug and play" amateur operation, but a part 15 compliant community radio station.
-Rich
 
Re: SSTRAN final input power

If I read you correctly, I agree. With the SStran power input to the final stage is limited to about 100 milliwatts. As a result, final amplifier efficiency suffers. Power output is reduced, and suffers, further, if you use any other load then the specified antenna. This is a kind of "power foldback" to try to keep the transmitter part 15 compliant.
It may not be optimal, but it is "plug and play", but range is limited.
-Rich
> Hello all,
>
> This is off topic from the original post, but I will address
> the previous few posts in this thread. I have measured the
> SSTRAN final input power and it is slightly under 100mW. and
> is independent of the load (four different short antennas
> tested).
>
> This will surprise those who have worked with higher power
> transmitters feeding efficient antennas, because the load
> certainly affects in final input power. But as I consider
> the situation with the SSTRAN, I conclude that the constant
> power input is due to very low power going to the antenna.
> The antenna power (microwatts or less) for a 3 meter antenna
> comes from the total input power (100 mW.) and therefore has
> a negligible effect on the total input power. Even if
> antenna power goes up by a decade, it is very small compared
> to 100 mW.
>
> Thus, we have a circuit where the input power is set by the
> predictable biasing and not the unpredictable load. The
> biasing in the SSTRAN is set to yield an input around 100
> mW. subject to part tolerance and is not adjustable. If you
> are running a "stock" transmitter then you can predict with
> high confidence that the input power is legal.
>
> If there is interest, I can post in a new thread how I
> measured the power input.
>
> Neil
>
 
Re: A question about grounds

> Hello,
>
> Just a question about something you wrote.
>
> "If the supporting structure is metal, grounded, has another
> use, and is pre-existing, then the ground can be considered
> an unintentional radiator."
>
> Is this an "official" interpretation of grounding for part15
> AM. Just curious as to where it came from.
>
> Thanks.
>
> Neil
>
An incidental radiator is a special case of unintentional radiator.
In 47 CFR 15.3(n) an incidental radiator is defined as:
[[Page 762]]



(n) Incidental radiator. A device that generates radio frequency

energy during the course of its operation although the device is not

intentionally designed to generate or emit radio frequency energy.
 
Re: A question about grounds

> > Hello,
> >
> > Just a question about something you wrote.
> >
> > "If the supporting structure is metal, grounded, has
> another
> > use, and is pre-existing, then the ground can be
> considered
> > an unintentional radiator."
> >
> > Is this an "official" interpretation of grounding for
> part15
> > AM. Just curious as to where it came from.
> >
> > Thanks.
> >
> > Neil
> >
> An incidental radiator is a special case of unintentional
> radiator.
> In 47 CFR 15.3(n) an incidental radiator is defined as:
> [[Page 762]]
>
>
>
> (n) Incidental radiator. A device that generates radio
> frequency
>
> energy during the course of its operation although the
> device is not
>
> intentionally designed to generate or emit radio frequency
> energy.
>




More like this instead....

[Code of Federal Regulations]
[Title 47, Volume 1, Parts 0 to 19]
[Revised as of October 1, 2000]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR15.3]

[Page 676-679]

TITLE 47--TELECOMMUNICATION

CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION

PART 15--RADIO FREQUENCY DEVICES--Table of Contents

Subpart A--General

Sec. 15.3 Definitions.

(z) Unintentional radiator. A device that intentionally generates
radio frequency energy for use within the device, or that sends radio
frequency signals by conduction to associated equipment via connecting
wiring, but which is not intended to emit RF energy by radiation or
induction.



Radiopilot
 
Re: A question about grounds

The Part 15 text that you posted _defines_ an unintentional radiator, but does not authorize its use for Part 15 AM.

Below is a quote from Part 15, Section 3. Note especially paragraphs (b) and (c).

+ + +

Authority: 47 U.S.C. 154, 302a, 303, 304, 307, 336, and 544a.

Source: 54 FR 17714, Apr. 25, 1989, unless otherwise noted.

(a) This part sets out the regulations under which an intentional,
unintentional, or incidental radiator may be operated without an
individual license. It also contains the technical specifications,
administrative requirements and other conditions relating to the
marketing of part 15 devices.
(b) The operation of an intentional or unintentional radiator that
is not in accordance with the regulations in this part must be licensed
pursuant to the provisions of section 301 of the Communications Act of
1934, as amended, unless otherwise exempted from the licensing
requirements elsewhere in this chapter.
(c) Unless specifically exempted, the operation or marketing of an
intentional or unintentional radiator that is not in compliance with the
administrative and technical provisions in this

[[Page 752]]

part, including prior Commission authorization or verification, as
appropriate, is prohibited under section 302 of the Communications Act
of 1934, as amended, and subpart I of part 2 of this chapter. The
equipment authorization and verification procedures are detailed in
subpart J of part 2 of this chapter.
//
 
Re: SSTRAN final input power

> If I read you correctly, I agree. With the SStran power
> input to the final stage is limited to about 100 milliwatts.
> As a result, final amplifier efficiency suffers.
___________

ALL Part 15 AM transmitters have an input power limit of 100 milliwatts -- the SSTRAN and the Rangemaster alike.

The measure of final stage efficiency is the amount of output power delivered to the load divided by the input power it took to produce it. That is likely to be something like 80%, or 80 mW out for 100 mW in.

Even if the final stage was, say 90% efficient, the difference in field strength that would produce is trivial,* other things equal. And nothing is 100% efficient.

*less than 0.5 dB

//
 
Re: A question about grounds-Rich's reply

Yes. You will note the similarities and differences between "incidental radiator" and "unintentional radiator" in the part 15 rules.
If you are arguing that FCC rules are often vague, I would have to agree with you. I understand the FCC gets many requests for clarification, even from the most expert, experienced engineers.
My associate, Dave McCrork, operator of WNAR-AM, contacted the FCC regarding his operation of WNAR-AM 1620 under part 15 rules. Made aware of the operation of WNAR-AM, and given a description, the FCC could find no apparent violations.
Dave operates an Radio Frequency certification and calibration laboratory and is also Chief Engineer of several Philadelphia area radio stations. He has the knowledge and experience to be considered expert in his field, and every reason, and the ability, to stay in compliance.
Dave has kindly posted more technical information on his website:
www.wnar-am.com
at ths link:
http://www.wnar-am.com/technical/description_of_loading_coil.htm
I guess the disclaimer "Results may vary" applies.
I hope this helps,
-Rich
> > > Hello,
> > >
> > > Just a question about something you wrote.
> > >
> > > "If the supporting structure is metal, grounded, has
> > another
> > > use, and is pre-existing, then the ground can be
> > considered
> > > an unintentional radiator."
> > >
> > > Is this an "official" interpretation of grounding for
> > part15
> > > AM. Just curious as to where it came from.
> > >
> > > Thanks.
> > >
> > > Neil
> > >
> > An incidental radiator is a special case of unintentional
> > radiator.
> > In 47 CFR 15.3(n) an incidental radiator is defined as:
> > [[Page 762]]
> >
> >
> >
> > (n) Incidental radiator. A device that generates radio
>
> > frequency
> >
> > energy during the course of its operation although the
> > device is not
> >
> > intentionally designed to generate or emit radio frequency
>
> > energy.
> >
>
>
>
>
> More like this instead....
>
> [Code of Federal Regulations]
> [Title 47, Volume 1, Parts 0 to 19]
> [Revised as of October 1, 2000]
> From the U.S. Government Printing Office via GPO Access
> [CITE: 47CFR15.3]
>
> [Page 676-679]
>
> TITLE 47--TELECOMMUNICATION
>
> CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
>
> PART 15--RADIO FREQUENCY DEVICES--Table of Contents
>
> Subpart A--General
>
> Sec. 15.3 Definitions.
>
> (z) Unintentional radiator. A device that intentionally
> generates
> radio frequency energy for use within the device, or that
> sends radio
> frequency signals by conduction to associated equipment via
> connecting
> wiring, but which is not intended to emit RF energy by
> radiation or
> induction.
>
>
>
> Radiopilot
>
<P ID="edit"><FONT class="small">Edited by SuperSound on 01/06/06 08:45 AM.</FONT></P>
 
Re: SSTRAN final input power-Rich's Reply

Actual calibration laboratory measurements of the SStran transmitter final amplifier working into a matched load, indicate an efficiency of substantially less then 50%.
Perhaps you would like the test measurements made under other conditions?
See http://www.wnar-am.com/technical/description_of_loading_coil.htm
scroll down to near the bottom of the page to where transmitter efficiency is discussed.
With flea power part 15 transmitters, every milliwatt of actual output counts. The greater, the better.
Perhaps the disclaimer "results may vary" applies.
I hope this helps,
-Rich

> > If I read you correctly, I agree. With the SStran power
> > input to the final stage is limited to about 100
> milliwatts.
> > As a result, final amplifier efficiency suffers.
> ___________
>
> ALL Part 15 AM transmitters have an input power limit of 100
> milliwatts -- the SSTRAN and the Rangemaster alike.
>
> The measure of final stage efficiency is the amount of
> output power delivered to the load divided by the input
> power it took to produce it. That is likely to be something
> like 80%, or 80 mW out for 100 mW in.
>
> Even if the final stage was, say 90% efficient, the
> difference in field strength that would produce is trivial,*
> other things equal. And nothing is 100% efficient.
>
> *less than 0.5 dB
>
> //
>
<P ID="edit"><FONT class="small">Edited by SuperSound on 01/06/06 08:50 AM.</FONT></P>
 
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