Where to find FM Transmitter?

[Hunter310]

Never mind I found it!


I am looking for a Vastelec FM2 transmitter, but cant find anything on eBay. Where would a good source be for this transmitter, or is there a better transmitter I should be looking at?

Thanks,

Steve E.

[jem5136]

Have you tried Googleing it? That may help. And I have never used one, but there is another FM Transmitter called the Whole House Transmitter, new they cost about $100, but you can look on ebay or other sites for them and sometimes can save a little money too.

Jesse

[rstehle]

Here ya go (http://cgi.ebay.com/30mW-FM-RADIO-STATION-TRANSMITTER-Circuit-Board-NEW-Ver-/400086173251?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item5d26fe8643). I don't think any of the eBay sellers call them VFM-02, but if you search for 30 mw transmitter, you can find them.

[Hunter310]

Thanks!

It was one of those things.... as soon as I hit submit, I found it.

Thanks for the reply.


Here ya go (http://cgi.ebay.com/30mW-FM-RADIO-STATION-TRANSMITTER-Circuit-Board-NEW-Ver-/400086173251?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item5d26fe8643). I don't think any of the eBay sellers call them VFM-02, but if you search for 30 mw transmitter, you can find them.

[BrianMiller]

I just purchased one of these:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320518870950#ht_5108wt_935



-Brian

[dirknerkle]

I just purchased one of these:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320518870950#ht_5108wt_935

-Brian

Hope you live in a rural area where there are no FCC people hanging around... that 5W is going to go for miles and miles. You can cover a whole town with that. You may want to look into ways to attenuate the signal at the antenna end or you could get in some hot water with that baby...

[BrianMiller]

Hope you live in a rural area where there are no FCC people hanging around... that 5W is going to go for miles and miles. You can cover a whole town with that. You may want to look into ways to attenuate the signal at the antenna end or you could get in some hot water with that baby...

I was a little worried about that. I've used many small FM transmitters in the past (years ago) and they were terrible. I figured this would be powerful enough.

I noticed the 200ft radius rule and the 50ohm load requirement for the antenna. I guess I could put the required load on the transmitter and not use an antenna at all. I'll have to figure something out......

Edit!: I can put the antenna in some sort of an enclosure with shielding.... It might even be adjustable. There are a few pictures here: http://www.elecsky.com/index.php?main_page=product_info&cPath=2&products_id=4 that shows a few POTs.

[oldcqr]

Last year (or was it 2 years ago?), I was spouting off that it would be the RIAA that came-a-knockin' to our display's before the FCC.

...

Then someone over at PC had the Men in Black show up at his door. He was WAY over the limit with a transmitter that was supposedly 'legal' (we're talking milliwatts here). Thankfully they were nice to him.

Ok, now granted the MiB showed up because this person has a Grinchy neighbor that doesn't like his show. But all it seemed to take was that one person to make one call.

Beware. 5W is going to draw attention.. FAST.

[BrianMiller]

Last year (or was it 2 years ago?), I was spouting off that it would be the RIAA that came-a-knockin' to our display's before the FCC.

...

Then someone over at PC had the Men in Black show up at his door. He was WAY over the limit with a transmitter that was supposedly 'legal' (we're talking milliwatts here). Thankfully they were nice to him.

Ok, now granted the MiB showed up because this person has a Grinchy neighbor that doesn't like his show. But all it seemed to take was that one person to make one call.

Beware. 5W is going to draw attention.. FAST.


Well crap,.. bummer I didn't see this forum before buying the darn thing.

What is the recommended FM power for an average display?

[budude]

You may want to look into attenuators to put in-line with your antenna to knock the signal down a bit. Every 3db is cutting it down in half. You would need to find one with the appropriate connectors, etc.

[IdunBenhad]

Hi:
Dirknerkle is right. Watch out for that high power. Besides, you don't need it. All you need to cover is the area in front of your display.

There have been many discussions on this. Just search this forum.

I used a Belkin type transmitter last season. It was an Ipod type transmitter and was literally taped into a window with no external antenna. It went for several blocks, which was far too much coverage.

For best results, work on the antenna, not the power. There are several discussions here on DIYC on this subject, also.

To find fm transmitters on Ebay, do a search for "PLL FM Transmitters".

Edit: Look up "T" or "Pi" attenuators on Google. They are easily made from carbon resistors. Another way is to use a 120 volt bulb as a load on the transmitter and actually use this as your antenna. It will probably radiate enough to serve as an antenna.

[BrianMiller]

You may want to look into attenuators to put in-line with your antenna to knock the signal down a bit. Every 3db is cutting it down in half. You would need to find one with the appropriate connectors, etc.

Thanks for the good ideas. I have a friend that works in RF and has access to a bunch of amps/attenuators for cable modems and such.

I'm going to try and return it first. If the seller doesn't let me, I'll be checking out attenuators.


-Brian

[BrianMiller]

Hi:
Dirknerkle is right. Watch out for that high power. Besides, you don't need it. All you need to cover is the area in front of your display.

There have been many discussions on this. Just search this forum.

I used a Belkin type transmitter last season. It was an Ipod type transmitter and was literally taped into a window with no external antenna. It went for several blocks, which was far too much coverage.

For best results, work on the antenna, not the power. There are several discussions here on DIYC on this subject, also.

To find fm transmitters on Ebay, do a search for "PLL FM Transmitters".

Years ago I used to work in the mobile electronics field. I have a bunch of FM modulators.

http://www.google.com/products/catalog?hl=en&q=FM+modulator&um=1&ie=UTF-8&cid=16028790313483356193&ei=t8bhS6-TN8L68AaJ0rCaDA&sa=X&oi=product_catalog_result&ct=image&resnum=5&ved=0CEMQ8gIwBA#

I wonder if I already have what I need :). Instead of putting this device in-line, plug an antenna into it.

[dmcole]

What is the recommended FM power for an average display?

Here's apparently the prevailing document (despite it being typed on typewriter in 1991):

http://www.fcc.gov/ftp/Bureaus/Mass_Media/Databases/documents_collection/pn910724.pdf

So, you'll be but a mere 500 million microwatts out of compliance ;) ... (my humanities education showing here -- 1/100 of a microwatt times 500 million is 5 watts, right?)

Anyway, I just went onto eBay, input "bnc attenuator" and found a couple that will do you, I think. I'd buy a big one -- there was a 10db for $9.50 -- install it and then do the drive-around-the-neighborhood test.

One of the ways I attenuated my signal was to have it below grade -- my office is in the basement and I installed the dipole on the wall, which probably knocks 6db or so off the signal in and of itself.

If the 10db one doesn't get you down to 200 feet, then buy another one.

Best o' luck.

\dmc

[BrianMiller]

Awesome.. These attenuators are showing a max input of 2W. I'm assuming pumping 5W into them would be bad? :)


-Brian

[dirknerkle]

Yep. that would be bad.

[hartlove]

...
I used a Belkin type transmitter last season. It was an Ipod type transmitter and was literally taped into a window with no external antenna. It went for several blocks, which was far too much coverage.
...

I'm surprised that these are working for people so well. I've tried several with my MP3 player in my truck, and have never been happy with the results. I guess I'll have to pull one out again and see if it works better just sitting in the yard.

[IdunBenhad]

Hi:
Back again!

Just read the rules concerning unlicensed operation for the FM band, and they place a range limitation of approx. 200 foot radius AND a maximum power of .01 watt. This regulation does not specify if that power level is input or output from the transmitter, so it may be safe to assume that it is output power. Usually, power output is used as the norm, so this actually allows an input on the order of twice the power output. Most transmitters are only 50% efficient.

If these limits put a crimp in your plans, you can consider putting the transmitter somewhere near the center of your display, or near the street and running the power/audio through a cable. Note that with careful design, the audio can be run through the power cable. It is injected at the control end through an RF choke/capacitor and extracted at the transmitter end the same way. The capacitors block the DC power, usually 12.5 vdc and the RF chokes keep the transmitter energy out of the cable and audio.

I still think using a bulb as an antenna will get you more than you need. I just reread the rules and the .01 microwatt is the ERP-Effective Radiated Power. This means if you have a 3 db gain antenna connected to the transmitter, you now have .02 microwatts, and it is illegal.

Work on the antenna. You will show more improvement in range, if needed, than in raising the power.

While you probably wouldn't be bothered by the Friendly Candy Company (FCC) for a block or two, the higher powered transmitter might just raise some eyebrows. Just keep your neighbors happy so that no one complains.

As noted by others, you probably can keep the transmitter you have, just cut down on its output power.

[bmcgeeny]

Hope you live in a rural area where there are no FCC people hanging around... that 5W is going to go for miles and miles. You can cover a whole town with that. You may want to look into ways to attenuate the signal at the antenna end or you could get in some hot water with that baby...

Trust me, that 5 watt $79 transmitter is probably more like .5 watt. If you already have it, look up your local amature radio club. Some one there will have a nice portable meter that can test it for you.

Too buy a REAL 5 watt transmitter is closer to the $1,000 range. Small low power ones are cheap, you start putting the big parts in them and they get expensive FAST.

[RPM]

Trust me, that 5 watt $79 transmitter is probably more like .5 watt. If you already have it, look up your local amature radio club. Some one there will have a nice portable meter that can test it for you.

Too buy a REAL 5 watt transmitter is closer to the $1,000 range. Small low power ones are cheap, you start putting the big parts in them and they get expensive FAST.

Not to mention that some of those inexpensive transmitters have some pretty poor filtering, and that is what may cause more problems.
The 2nd or 3rd harmonics can cause more problems than the primary frequency itself.

[BrianMiller]

I looked up a few reviews for the CZH-5A. Some said 2 miles and some said 3000 meters. While it might be a crappy 5W, it's still too much for what I need.

I looked up attenuators--they cost more than the transmitter. I have a handful of 75ohm 20db attenuators on-hand but I don't know if they'll work correctly and safely with the 50ohm transmitter. Not to mention the input wattage exceeds that of the attenuators.


-Brian

[IdunBenhad]

Hi:
If anyone is interested in the iPod transmitters, go to Ebay and search for:

USB 215 TRANSMITTER.

This is the one I used this past season. I left it on all the time, with a wall wart, because if it was powered down, it would not return to the frequency it had been set on.

Also, do a search here for "Spare FM transmitter" for more information.

[BrianMiller]

Ok,.. the seller has a .5w on hand. Is .5watt enough?



-Brian

[IdunBenhad]

Hi:
.5 w is more than enough. Again, work on the antenna, not the power.

Just guessing, but I would say that the 215 transmitter i mentioned is probably no more about 10 mw, at the most.

[BrianMiller]

Here is the device I grabbed.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=320515083205&ssPageName=STRK:MESE:IT#ht_3337wt_941


So you think .5 watt will exceed the 200ft radius? Crap.... more screwing with the antenna...

[IdunBenhad]

Hi:
Wow. That looks like a nice TX, but you really didn't have to spend that much money to get a good one. Sorry to rain on your parade.

BUT, just connect it to a vertical dipole type antenna and maybe keep it inside the house. You should get plenty of coverage and not set off any alarms. Just experiment with the location of the antenna and remember, just because you have the capability to go 10 blocks doesn't mean you have to. While big coverage is good for the ego, it is not necessary. All you need is to cover the area near your display with a good, clean signal.

Seems I always have to look twice. The antenna supplied with the TX may be just the ticket. Just experiment with its placement to arrive at the coverage you need.

[BrianMiller]

Hi:
Wow. That looks like a nice TX, but you really didn't have to spend that much money to get a good one. Sorry to rain on your parade.

BUT, just connect it to a vertical dipole type antenna and maybe keep it inside the house. You should get plenty of coverage and not set off any alarms. Just experiment with the location of the antenna and remember, just because you have the capability to go 10 blocks doesn't mean you have to. While big coverage is good for the ego, it is not necessary. All you need is to cover the area near your display with a good, clean signal.

Seems I always have to look twice. The antenna supplied with the TX may be just the ticket. Just experiment with its placement to arrive at the coverage you need.

Excellent,

Unfortunately, the seller was only willing to give me a lower power device that was comparable in price. his $80 5Watt may have been crap,.. his $80 .5Watt seems to be nicer... :)


-Brian

[ElDiablo]

If you want reliability and to put out RDS for your listeners etc etc, the best one i've found so far thats cheap, reliable and recommended is this lot from EDM Design:
http://www.edmdesign.com/orders.html

for instance: EDM-TX-10P: 10mW PCB, Parts, Antenna, Regulated 12V PSU for $115 inc shipping and handling...
or if you wanna go all out with RDS and and LCD screen,
EDM-LCD-RDS-EP
10/100mW PCB, TX Parts, LCD display, Antenna, Regulated 12V PSU, Metal enclosure RF adjustable (1-10mW and 2-100mW) RDS chip & data cable included for $225 inc S&H..
I've heard alot from the guys on various christmas forums about these kits and their reliablilty even over the Whole House transmitters.. I've got one of the LED ones on order :) gotta wait 2 weeks to get it shipped over to the UK, but i think i'll live :P lol