FM transmitter of choice...

[radiopilot]

Re: I'm using the EDM 100...

> > > "I've not had a single complaint as the PCFM has double
> > > bandpass filters and the FMS amplifier has double
> > filtering
> > > as well,"
> > >
> > > But if one uses the pico with the add on FMS amplifier
> it
> > > won't be FCC approved anymore. For part15 you are not
> > > allowed to add any amplifiers to a part15 device.
> > >
> >
> > Radiooke,
> >
> > Just to clear the air, I don't have the FMS amplifier, I'm
>
> > just using the PCFM, the reference is for those wishing to
>
> > up the signal, that the amplifier also carries the
> > filters... I should have made it more clear, but you are
> > correct in your statement about adding power amplifiers to
>
> > any Part15 device... the only way to use the any amplifier
>
> > is to be certified with the system by the FCC.
> >
> > Radiopilot
> >
>
> Sometimes people think if they have a approved type FCC
> transmitter they can add a approved type FCC amplifier and
> that it would still be approved!
>

I'm sure you and I know this but just for those who may want to read it, here it is:

TITLE 47--TELECOMMUNICATION

CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION

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

Subpart C--Intentional Radiators

Sec. 15.204 External radio frequency power amplifiers and antenna modifications.

(a) Except as otherwise described in paragraph (b) of this section,
no person shall use, manufacture, sell or lease, offer for sale or lease
(including advertising for sale or lease), or import, ship, or
distribute for the purpose of selling or leasing, any external radio
frequency power amplifier or amplifier kit intended for use with a Part
15 intentional radiator.
(b) A transmission system consisting of an intentional radiator, an
external radio frequency power amplifier, and an antenna, may be
authorized, marketed and used under this part. However, when a
transmission system is authorized as a system, it must always be
marketed as a complete system and must always be used in the
configuration in which it was authorized. An external radio frequency
power amplifier shall be marketed only in the system configuration with
which the amplifier is authorized and shall not be marketed as a
separate product.
(c) Only the antenna with which an intentional radiator is
authorized may be used with the intentional radiator.




I guess my real question is.... if the part15 device is already at part15 levels why would the FCC allow a separate amplifier to be added to the 'system' at all, even to achieve part15 levels? Go figure????? My only guess is carrier current but then (c) indicates 'Only the antenna with which....." Huhh?

Radiopilot

 

[murphmac]

Re: Link to fm transmitter info

> > I have found an interesting link talking about the
> > transmitter as well as some other fm transmitters. In
> > additon he talks about remaining faithful to part 15 in
> > connection with the antenna etc
> > http://global-cm.net/distribu.html
> _________
>
> I don't know who wrote the text on that URL (partial clip
> below), but they are WAY off the mark as far as what Part 15
> allows for systems in the FM broadcast band.
>
> Part 15 does NOT allow a "100 mW maximum limit" for Part 15
> FM systems. That is a Part 15 AM Rule.
>
> A radiated power of only ~11.4 nanowatts is needed to
> generate the maximum legal Part 15 FM field from a simple
> 1/2-wave dipole. Ramsey, EDM and the "Pico" units all are
> rated for _far_ more power than necessary for legal Part 15
> FM operation at the maximum legal field strengths.
>
> + + +
>
> PARTIAL CLIP from global-cm.net
>
> "RF output level of about dBmV translates to just under
> 100 microwatts of power. This is about 20 dB less than
> that found
> on the typical Ramsey FM 10, which is close to the legal
> power limit
> in the United States, under 10 milliwatts ( dBmV). Adding
> an
> amplifier to match the ballpark legal limit of 100
> milliwatts
> ( dBmV) is somewhat difficult for the layman to calculate.
> It is
> correctly described as 250 microvolts received on a 1-meter
> dipole
> antenna, distance at 3 meters from transmitting antenna. A
> very
> efficient antenna when connected to the Ramsey units can
> actually
> put you over the legal limit. Their FM-25 unit when set to
> the
> "export" output position and coupled to ANY antenna will
> exceed
> the FCC limits. Do at your own risk, but be well aware of
> the pen-
> alties, should you be so unfortunate as to be made an
> enforcement
> example.
>
> How to get the PCFM up to near the legal power level? The
> cheap
> and "dirty" way would be to connect an inexpensive VHF
> distribution
> amplifier to the output of the PCFM, and then to an antenna
> system.
> The PICO TA-25 will get you within 5 dB of the 100 mW
> maximum limit.
> Just over dBmV is a pretty respectable power level, if you
> are
> on a restricted budget."
> //
> Lets keep in mind that the power that the FCC alows for legal part 15 FM is really only be beneficial if you want to broadcast in other rooms of your house. Depending on how large you house is, you probably would'nt even get decent coverage. If you go by the EXACT FCC rules for FM - you would rather stick with AM. The amount of power allowed for FM is so small that it really would'nt be worth investing money for equipment. It's really a shame that this rule is not modified. 100MW or even 1/2 watt would work fine as long as your antenna is not too high and that you do not interfere with other stations. THis
.0000000000000001 thing is ridiculous! ( exaggerated but you get my point)

Jim

 

[rfry]

Re: Link to fm transmitter info

> Lets keep in mind that the power that the FCC alows for
> legal part 15 FM is really only be beneficial if you want to
> broadcast in other rooms of your house....THis
> .0000000000000001 thing is ridiculous! ( exaggerated but you
> get my point)
________

It is ridiculous only to people wanting to "broadcast" beyond the distance limits that observance of FCC Part 15 FM Rules enable.
//