SainSonic FM Transmitter...

[dewbscott]

All;

I bought one of these little guys from Amazon after my disappointment with the Whole House FM Transmitter offered through LOR and other sites on the 'net:

http://www.amazon.com/SainSonic-Stereo-Broadcast-Transmitter-Antenna/dp/B0096KYDF8/ref=sr_1_6?s=electronics&ie=UTF8&qid=1356635848&sr=1-6

You can also find them cheaper on eBay - they all look like minor variants of the same basic model.

Tonight is my first night with it (still running my little show) and I am very pleased. However, some folks may balk at the high output power (5 milliwatts) and FCC Part 15 rules. I tried to read the Part 15 rules but didn't know how to translate the micro-volts to milliwatts, so I have no idea if this breaks any Part 15 rules or the frequency characteristics in my neighborhood. I do know that I'm using this on a "vacant" frequency and I have the transmitter on "low" power (1 milliwatt).

If, for any reason, the "FCC Man" shows up and tells me to cease transmitting the music for my innocent little light show then I will do so immediately. I did want to post the instructions on how to limit the output power for these little transmitters for anyone who has one/is curious. I especially liked the frequency band upper/lower limit - I pulled these instructions off of an eBay posting:

Thanks;

Don

Transmitter power adjustment instructions

■ The transmit power can be switched. First unplug the power, hold down the power button, and then plug in the power, after three seconds, release the Power button, the display shows the letter H, and then press + - buttons to convert H or L;

■ H high-power, L low-power; press the Power button to confirm the selected

After setting the transmit power, the machine will automatically enter the settings of frequency range ,

The selected frequency range also through the + - buttons to set the upper frequency limit, then press the Power button to confirm, and then set the lower frequency limit, press the Power key to confirm,

the screen display OFF when the setting is completed, can be normal working.

[craigecooper]

i bought one off ebay for ~50. Works great and I think it is set on H. It starts to fade out a few houses down the street so I doubt anyone would care. My neighbor behind me is walking on a valid FM station so I think I'll be ok.

[Max-Paul]

Slight correction. 1.0 is one watt, .5 is 500mW and .1 is 100mW

I agree the unit of measurement is rather hard to figure out. But keep this in mind, you can attach good or poor coax and you can attach an antenna that has no gain or one that has gain. So, What the FCC did is they said that with a calibrated meter and at a meter distance from the antenna. It can only have so much energy on their meter. Someone smarter than me figure it out to be about 200 or was it 300 feet from the antenna. Lets face it, if they cant see the show clearly, why bother sending out a signal further than that. Now I will have to say, I want a good clean signal out that 200 feet, then static after that. And I am sure the boys in black aint going to give you trouble if that distance varies some from night to night as do the commercial radio signal shift distance on different night.

What will get you on the wrong side of things is if you blast for miles around. One guy bragged that he could be hear for I think it was 5 miles away. And this is possible even with 500mW if you are on high ground with a clear shot across a wide valley. At the same time that same 500mW wont go more than a few hundred feet if you have lots of trees around your house (all sides) and you live in a depression/gully. d that is possible even with a mere half of watt (.5

[viennaxmas]

Last week a viewer asked if I had a 5 KW transmitter... That would be 5,000 W... Might blow a hole in the roof right where the antenna sits... Considering the two 10 DB attenuators, I am on 0.22 W - which covers about 250 ft with clear signal :-)

5000 would be enough to serve as HD transmitter at a commercial station with a 300 ft tower and could be heard about 50 miles... That would get me in trouble...

[Max-Paul]

5KW and only heard 50 miles? Is your state one of the states that has now legalized Mary Jane? Have ever been even close to a 1KW station or greater? I have and it was actually a 3KW transmitter. I was located on the southern coast of Turkey, to the far right edge. We talked to Germany any time we wanted. Might have to change what H.F. band we were on, but always was able to make contact. I should think that with a few more KW New York would not have been a problem. I am also KF0OX and talked to middle of Africa, Botswana by name on a mer 100W and a vertical antenna. But the conditions had to be just so to do so.

I suspect you have no concept of what 5KW can do. Even though we are in the lower VHF frequencies. BTW HAMS bounce off of the moon on 144Mhz with just 1KW.

Edited December 28, 2012 by Max-Paul

[viennaxmas]

I'll ask my viewer what he is smoking...

For the range: on AM or shortwave you are able to cover much more distance with the same power. On FM? Not so much. Most commercial radio stations operate between 10 KW and some of the large ones at 50 KW and their coverage is quite limited. Otherwise you could tune to WNYC from LA... Repeaters are between 100 W and 5 KW... (50KW is actually the largest I have worked with)

Some of the largest short wave stations located on coastal areas are operating at up to 1 MW and they use bouncing of the sea to cover long distances.

I am surprised about being able to cover large distances in the 2 Meter band. That only works if the atmospheric conditions are ideal. Otherwise is is considered to be a more "local" thing :-)

[viennaxmas]

http://zhc-fm-transmitter.com/2012/09/20/how-far-fm-transmitter-can-cover/

Pretty good overview on FM and distances...

[Max-Paul]

The lower Mhz 144 -145 has several different modes. Not all of the 2 mtr band is FM. I agree FM does take a bit more power in order to work. Cause with FM you cut off the peaks where the noise resides like it does on AM, or SSB a form of FM. You did not specify what mode of modulation. I assumed that the HD was Heavy Duty Transmitter as a 5KW would be.

It sounds like you are also a radio man. I agree our 25W FM transmitters reached out to aircraft that where 75 mile or closer coming into the base. While SSB was used for long range comm.

[PMC]

Slight correction. 1.0 is one watt, .5 is 500mW and .1 is 100mW

I agree the unit of measurement is rather hard to figure out. But keep this in mind, you can attach good or poor coax and you can attach an antenna that has no gain or one that has gain. So, What the FCC did is they said that with a calibrated meter and at a meter distance from the antenna. It can only have so much energy on their meter. Someone smarter than me figure it out to be about 200 or was it 300 feet from the antenna. Lets face it, if they cant see the show clearly, why bother sending out a signal further than that. Now I will have to say, I want a good clean signal out that 200 feet, then static after that. And I am sure the boys in black aint going to give you trouble if that distance varies some from night to night as do the commercial radio signal shift distance on different night.

What will get you on the wrong side of things is if you blast for miles around. One guy bragged that he could be hear for I think it was 5 miles away. And this is possible even with 500mW if you are on high ground with a clear shot across a wide valley. At the same time that same 500mW wont go more than a few hundred feet if you have lots of trees around your house (all sides) and you live in a depression/gully. d that is possible even with a mere half of watt (.5

+1, I could not of worded it better

And if I was going to buy a factory made FM Transmitter it goes from 0.001W to 5W if you search the net you will get a better price but this link gives a detailed description

Edited December 29, 2012 by PMC

[PMC]

All;

I bought one of these little guys from Amazon after my disappointment with the Whole House FM Transmitter offered through LOR and other sites on the 'net:

http://www.amazon.co...56635848&sr=1-6

You can also find them cheaper on eBay - they all look like minor variants of the same basic model.

Tonight is my first night with it (still running my little show) and I am very pleased. However, some folks may balk at the high output power (5 milliwatts) and FCC Part 15 rules. I tried to read the Part 15 rules but didn't know how to translate the micro-volts to milliwatts, so I have no idea if this breaks any Part 15 rules or the frequency characteristics in my neighborhood. I do know that I'm using this on a "vacant" frequency and I have the transmitter on "low" power (1 milliwatt).

If, for any reason, the "FCC Man" shows up and tells me to cease transmitting the music for my innocent little light show then I will do so immediately. I did want to post the instructions on how to limit the output power for these little transmitters for anyone who has one/is curious. I especially liked the frequency band upper/lower limit - I pulled these instructions off of an eBay posting:

Thanks;

Don

Transmitter power adjustment instructions

■ The transmit power can be switched. First unplug the power, hold down the power button, and then plug in the power, after three seconds, release the Power button, the display shows the letter H, and then press + - buttons to convert H or L;

■ H high-power, L low-power; press the Power button to confirm the selected

After setting the transmit power, the machine will automatically enter the settings of frequency range ,

The selected frequency range also through the + - buttons to set the upper frequency limit, then press the Power button to confirm, and then set the lower frequency limit, press the Power key to confirm,

the screen display OFF when the setting is completed, can be normal working.

The FCC limits PART 15 FM by field strength, not by transmitter power. You're allowed only 250 µV (micro-volts) per meter at a range of about 10ft to be completely legal, This would put the transmitter power in the range of a few dozen µW, (micro-watts)

Edited December 29, 2012 by PMC