Project 1710

My guess is if you contact Phil via electronic mail he will be able to help you. I would aalso guess that there is DIP setting to affect that change.

I'll bet on a wire antenna you'd get that field strength at 100mW.  you'd have to get some sort of FIM just like the Potomac for FM.

There would have to be a way to fold back the power or de-tune the antenna.

Thank you John, WDCX, luckily I have the DIP settings for 1710 on the SSTransmitters...

S4 :: up down up down up down up down;

S5 :: up down up up.

My early reading of 15.233 raises curiosity as to bandwidth, but I don't know enough yet to form a meaningful question.

TheLegacy, 100mW is your guess.

I don't yet have a guess.

I would not worry about bandwidth. 🙂

he can run carrier current under 15.223 without issue. that field strength is calculated from the radiating source and it is not specified anywhere what that radiating source has to be. this applies to all the part 15 freuqencies yes even on fm where radiating cable is used in place of electrical wires.

and last i knew carl was set up to do carrier current.

carl you might try using that SSTRAN as a driver and modifying the LPB to use as a amplifer stage. feed that into your breaker box via your coupler on 1710.

The rule for CC is 15.221 - Operation in the Band 525-1705 kHz.

As far as I can tell the only way to do 1710 is by 15.223.

§15.223   Operation in the band 1.705-10 MHz.

(a) The field strength of any emission within the band 1.705-10.0 MHz shall not exceed 100 microvolts/meter at a distance of 30 meters. However, if the bandwidth of the emission is less than 10% of the center frequency, the field strength shall not exceed 15 microvolts/meter or (the bandwidth of the device in kHz) divided by (the center frequency of the device in MHz) microvolts/meter at a distance of 30 meters, whichever is the higher level. For the purposes of this section, bandwidth is determined at the points 6 dB down from the modulated carrier. The emission limits in this paragraph are based on measurement instrumentation employing an average detector. The provisions in §15.35(b) for limiting peak emissions apply.

That's a full quote of 15.223 provided by Rich, and that's what I am planning to implement if it's within my capability to achieve.

It won't be as cut and dried as with 15.239, which can be simply solved by using a certified transmitter.

Between now and December I'll ponder the rule itself, de-coding what it actually says.

Assuming that I come to an understanding of the text, it will be time to do something physical, like an AMT3000 with a 2" antenna or whatever it takes.

Maybe this field strength allowance is even more feeble than the part 15 FM strength, but we don't know that yet.

It is important to keep a list of what one does not know.

and again carl, carrier current can be used in any band under part 15 where it is technically feasible and governed by field strength, there is no regulatory restrictions limiting carrier current to 15.221. carrier current if i recall is feasible up to about 3 MHz. above that you have to get into radiating cable.

Part 15.223 more carefully read/understood shows that radiated field intensity for an AM broadcast application on 1710 kHz is limited to 15 uV/m at a distance of 30 meters.  That is below the ambient r-f noise level in most receiving environments.

An AM transmitter on 1710 kHz with an r-f spectrum bandwidth of 10 kHz produces a smaller result than the 15 uV/m limit, so 15 uV/m (the greater value) is the limit.

Note the text below having these attributes:

CLIP FROM FCC PART 15.223:

(a) The field strength of any emission within the band 1.705-10.0 MHz shall not exceed 100 microvolts/meter at a distance of 30 meters. However, if the bandwidth of the emission is less than 10% of the center frequency, the field strength shall not exceed 15 microvolts/meter or (the bandwidth of the device in kHz) divided by (the center frequency of the device in MHz) microvolts/meter at a distance of 30 meters, whichever is the higher level. For the purposes of this section, bandwidth is determined at the points 6 dB down from the modulated carrier. The emission limits in this paragraph are based on measurement instrumentation employing an average detector. The provisions in §15.35(b) for limiting peak emissions apply. //

Rich predicts: "That (field strength under 15.223) is below the ambient r-f noise level in most receiving environments."

That is why it appeals to me. My own radio station on 1710 will become a major DX prize even in the same house.

Will I be able to pick it up? Things are getting to be more than a little fun.

So, if I fuss with the output tuning and power to get way down into the noise floor, will that be close enough?

Mr Blare asked:

... So, if I fuss with the output tuning and power to get way down into the noise floor, will that be close enough?

Maybe yes, and maybe no.

But what would be the point of doing so, if for systems compliant with FCC §15.223, such transmissions were rendered by ambient r-f noise to be unusable in the real world, at distances of 30 meters and even less from the transmit antenna?

Those wanting to pass FCC scrutiny/action would be better off using an unlicensed system fully compliant with FCC §15.219, operating in the upper few hundred kilohertz of the AM broadcast band ending at 1700 kHz.

Unlicensed AM systems meeting FCC §15.219 in the r-f spectrum ~1500 kHz to 1700 kHz legally can produce much greater fields at all distances than are legally possible under FCC §15.223 when using 1710 kHz.

30 meters is 100-feet, and by coincidence the distance from the house to the street is 100-feet, so if I take a SENSITIVE radio down to the street and back-off transmission strength so the signal gets lost in the background, that should be about it.

Recalling Rich's words: "That is below the ambient r-f noise level in most receiving environments."

I will also suppose that this determination is best done during the daytime, since at night everything is buried in noise.

ADDENDUM -- I just spotted Post # 14 which questions why a person would fiddle with such low output strength when 15.219 offers so much more range.

I think it has to do with the fact that it is a permitted section of the Part 15 rules, and I want to do them all.

After all, at 10 or 20 feet from the transmitter it will be recievable.

I kind of like the idea of being unreceivable by the public. They have those sports and religious stations. There seems to be no demand for intelligent programming.