FM transmitter

[Guest guest]

DonFL wrote:

st
FM may or may not be referring to operation at FM radio freqs, VHF/UHF is a wide range....hard to say. Anytime you don't see printed specs for an antenna, you can be pretty sure it is very wide band, intended for receive use only.

JBullard clarified my point..you can use a coat hanger for a receive antenna and get performance, but on the transmit side, a bad match means a lot of reflected energy, and solid state finals don't like that.

The antenna, as described, is likely designed as a very wide band all purpose receive antenna...not really made for hobby FM transmitter use.

Why not just add additional attenuation and use the antenna sent with the transmitter?

Actually just got a reply from a HAM Radio site and they said, it wouldn't work very well (although it does seem to work just fine from what I have tested with it), but on their recommendation, as well as what Jbullard and you've said, I removed it and changed it back to the original unit. Even with the attenuator, the darn thing still broadcasts way too far (up to 2+ mile radius). This is with a 10Db attenuator, are there larger Db rated ones? I was hoping to be able to use it, as it would have made anyone messing with the antenna more difficult by being mounted INSIDE the enclosure, where no one could get at the antenna and damage it. So much for that idea I guess.

I don't have room for more than one attenuator due to where, and how the transmitter is, and has to be mounted in the enclosure. Was told I could use two in series, but just no room for more than one in the box! (It's mounted with the LOR DC-MP3 Showtime Director in the same housing.)

[JBullard]

Orville wrote:

DonFL wrote:

st
FM may or may not be referring to operation at FM radio freqs, VHF/UHF is a wide range....hard to say. Anytime you don't see printed specs for an antenna, you can be pretty sure it is very wide band, intended for receive use only.

JBullard clarified my point..you can use a coat hanger for a receive antenna and get performance, but on the transmit side, a bad match means a lot of reflected energy, and solid state finals don't like that.

The antenna, as described, is likely designed as a very wide band all purpose receive antenna...not really made for hobby FM transmitter use.

Why not just add additional attenuation and use the antenna sent with the transmitter?

Actually just got a reply from a HAM Radio site and they said, it wouldn't work very well (although it does seem to work just fine from what I have tested with it), but on their recommendation, as well as what Jbullard and you've said, I removed it and changed it back to the original unit. Even with the attenuator, the darn thing still broadcasts way too far (up to 2+ mile radius). This is with a 10Db attenuator, are there larger Db rated ones? I was hoping to be able to use it, as it would have made anyone messing with the antenna more difficult by being mounted INSIDE the enclosure, where no one could get at the antenna and damage it. So much for that idea I guess.

I don't have room for more than one attenuator due to where, and how the transmitter is, and has to be mounted in the enclosure. Was told I could use two in series, but just no room for more than one in the box! (It's mounted with the LOR DC-MP3 Showtime Director in the same housing.)

Interesting - at least 3 hams (myself included) are in this thread, and we also use the low power transmitters in our Christmas displays - in a legal way at least in my case ( can only speak to my own use) - but you must not have believed us -

and yes, you can get attenuators larger then 10 db - ( but why ask us - you probably won't believe what we say regarding attenuators either )

[Guest guest]

JBullard wrote:

Orville wrote:

DonFL wrote:

st
FM may or may not be referring to operation at FM radio freqs, VHF/UHF is a wide range....hard to say. Anytime you don't see printed specs for an antenna, you can be pretty sure it is very wide band, intended for receive use only.

JBullard clarified my point..you can use a coat hanger for a receive antenna and get performance, but on the transmit side, a bad match means a lot of reflected energy, and solid state finals don't like that.

The antenna, as described, is likely designed as a very wide band all purpose receive antenna...not really made for hobby FM transmitter use.

Why not just add additional attenuation and use the antenna sent with the transmitter?

Actually just got a reply from a HAM Radio site and they said, it wouldn't work very well (although it does seem to work just fine from what I have tested with it), but on their recommendation, as well as what Jbullard and you've said, I removed it and changed it back to the original unit. Even with the attenuator, the darn thing still broadcasts way too far (up to 2+ mile radius). This is with a 10Db attenuator, are there larger Db rated ones? I was hoping to be able to use it, as it would have made anyone messing with the antenna more difficult by being mounted INSIDE the enclosure, where no one could get at the antenna and damage it. So much for that idea I guess.

I don't have room for more than one attenuator due to where, and how the transmitter is, and has to be mounted in the enclosure. Was told I could use two in series, but just no room for more than one in the box! (It's mounted with the LOR DC-MP3 Showtime Director in the same housing.)

Interesting - at least 3 hams (myself included) are in this thread, and we also use the low power transmitters in our Christmas displays - in a legal way at least in my case ( can only speak to my own use) - but you must not have believed us -

and yes, you can get attenuators larger then 10 db - ( but why ask us - you probably won't believe what we say regarding attenuators either )

Now wait a minute I don't know who is a ham operator and who isn't here, many times I would have no idea. I know Don said he was, but he wasn't completely sure if it would or not. And I ASKED right after Don had mentioned that at the site that sells Ham Radio equipment(antennas), for one thing I wanted another opinion since I had two fellows in local CB radio stores near me saying it should work.

And if I don't ask, or tell someone what I'm attempting how the hell would I ever LEARN ANYTHING?

And again, not knowing if they were Ham operators or not. If this WERE A HAM OPERATORS site that would be a different ballgame, but it IS NOT, it is a CHRISTMAS/HOLIDAY LightShow decorators site. Aside from that, I AM NOT a ham operator, so I wouldn't even be on those sites.

So I'm sorry you take offense at my trying to be 100% certain on something I was trying to do, and then asking additional questions about something (attenuators) that I KNOW VERY LITTLE about except for the one recommended when I first got the transmitter. And why I asked if they come in high Db ratings.

It's responses like this that NEW folks WON'T EVER LEARN anything, because it will make them afraid to even ASK A SIMPLE QUESTION about something, especially if they may not know much about the item in question.

And I NEVER stated anywhere that I DID NOT BELEIVE ANYONE about this, I simply stated I thought it would work because I had tried and it seemed to be working just fine. Nothing more and nothing less.

Just where did I say I didn't believe anyone?

Geez, just trying to get answers so I don't damage something, and this is what I get for asking. I'm sorry I asked!

[Guest guest]

Deep breath...everyone....

The reason I asked about your antenna is I was pretty sure it would not work once you mentioned "rubber ducky"...and honestly, ham radio licensee or not, its just a matter of looking at the specs for the antenna...when I went to the site you linked me to, the fact that the it had no specs, that pretty much confirms it. That kind of antenna is simply not typical/standard for fm transmitter use, low power or otherwise.

You can buy a larger attenuator..so you don't have to stack them. You're not needing anything with a high power rating.

I'm not familiar with your transmitter and set up, connnector type, etc, so tough to recommend how much further you need to pad it down, how you want to install it, what type of attenuator to get, etc..another 10 dB (so 20 total) is where I would start. I'm sure ebay, among other sites, will give you plenty of options to choose from..again, not knowing your setup, can only give you guidance, not concrete answers. Please do not take this and say "well, Don said 20 dB of attenuation will solve my problem"...

Before you take this next step, you may want to do a little reading on transmitters and antenna theory...it will help clarify the concept of needing a good match between antenna and transmitter, explain the concept of a dB as it relates to attenuation and gain, etc.

There are tons of resource out there on the web that will help make things clearer for you. It isn't rocket science...

It also sounds like that CB shop (and radio shack) you refer to is best avoided for any further advice..

[Ron Amedee]

DonFL wrote

Before you take this next step, you may want to do a little reading on transmitters and antenna theory...it will help clarify the concept of needing a good match between antenna and transmitter, explain the concept of a dB as it relates to attenuation and gain, etc.

And it helps to have the right equiptment if you are going to get serious about it!

Attached files

[Guest guest]

Ahhhh...a Bird wattmeter...the old style, with interchangeable slugs...

Now I'm getting all misty-eyed...:cool:

[JBullard]

Yes, a fine piece of equipment ( as I wipe my eyes also)

[Ron Amedee]

If you Like that, Now this is OLD school!!

Attached files

[Guest guest]

DonFL wrote:

Deep breath...everyone....

The reason I asked about your antenna is I was pretty sure it would not work once you mentioned "rubber ducky"...and honestly, ham radio licensee or not, its just a matter of looking at the specs for the antenna...when I went to the site you linked me to, the fact that the it had no specs, that pretty much confirms it. That kind of antenna is simply not typical/standard for fm transmitter use, low power or otherwise.

You can buy a larger attenuator..so you don't have to stack them. You're not needing anything with a high power rating.

I'm not familiar with your transmitter and set up, connnector type, etc, so tough to recommend how much further you need to pad it down, how you want to install it, what type of attenuator to get, etc..another 10 dB (so 20 total) is where I would start. I'm sure ebay, among other sites, will give you plenty of options to choose from..again, not knowing your setup, can only give you guidance, not concrete answers. Please do not take this and say "well, Don said 20 dB of attenuation will solve my problem"...

Before you take this next step, you may want to do a little reading on transmitters and antenna theory...it will help clarify the concept of needing a good match between antenna and transmitter, explain the concept of a dB as it relates to attenuation and gain, etc.

There are tons of resource out there on the web that will help make things clearer for you. It isn't rocket science...

It also sounds like that CB shop (and radio shack) you refer to is best avoided for any further advice..

Thnaks Don.



This is all I can tell your about my set up: Mobile Black Box Eclipse-4000 FM Transmitter, 500mW rating, transmits up to 1,600 ft {although has gone much furthe than that} this was info from their website and the manual. I'm not sure what all you need to know on the transmitter.

It is housed with my DC-MP3 Director inside a weatherproof plastic case (not so much weatherproof anymore...won't go into that.)

I used to *KNOW* all this antenna stuff when I was into CB and had equipment for installing their antenna systems. But I have not been in CB now since, good grief, probably last time I used and owned one was back in or aound 1984 or 1985. And sold all that equipment. Never figured I'd ever have a need for it again.

I did find a 20dB attenuator(largest one they sell) at the site I linked for the 10dB one. So I will give that a try and hope it works as well in cutting the distance down, as the rubber ducky antenna did. I would just like to get it to stay at or around that less than 1/2 of 1/10th of a mile range. It does make me a wee bit nervous when it transmits within a 1+, sometimes 2+ mile radius using the 10dB attenuator.

I tried to find the darn data sheet (specs) on the Rubber Ducky antenna, couldn't find anything on the Radio Shack site, since it was bought from Radio Shack was hoping I could have found the info there. Seems they no longer sell them, so no data was any longer available on them.

A common error I keep making with antenna are that if it says UHF.VHF/FM, in my thoughts it should work for both incoming and outgoing usage. But from what I've learned here and from the Ham site that sells antenna, that's not correct.

And I'll bet I am NOT the only person out here that makes the presumption that an antenna thusly labeled: "can be used for AM/FM, UHF/VHF/FM" would be useable for an FM Transmitter either.

So I learned some new things or possibly "relearned" some old things that I just stored way back in my mind since I haven't used them in over 25 years or so.

Although on the FM antenna, this was all new too me as I always thought ANY FM labeled antenna could be used for incoming or outgoing signals. So I've got to maked a note of this for future reference.

Once again, thank you for your help Don. It is very much appreciated and I've learned a new thing I didn't know!


EDIT: BTW: the idiot at Radio Shack that told me that, is no longer working there. I went back in to make a complaint about getting "bad" advice that could have damaged my FM Transmitter by being told I could use a rubber ducky scanner antenna, when I should not be. Seems this bozo had had several complaints on him previously, NOT knowing their products properly and giving out misinformation. So RS fired him. Good for them! I won't go back to the other place either!

I will go to a Radio Shop I found that DOES KNOW their stuff and criteria about this stuff, as they deal with HAM/AIRCRAFT/CB Radios, Scanners and I think they might sell FM Transmitters as well, and a lot of other stuff I didn't recognize, or know what the heck it is, or was. LOL

I believe they are called (if I get their name right) AES, only been there twice now, so I'm not sure that's the correct name, I just KNOW where they are if I need anything repaired, replacement antenna, etc.

[Guest guest]

Don, this taken directly from the MBB site (if it helps):

Eclipse-4000 FM audio transmitter technical specifications* :

■Dimensions: 5.75" (L) X 3.75" (W) X 1" (D)
■Weight: 11.5 ounces
■Case material: Metal (aluminum)
■Transmit Frequencies: 87.5 ~ 108 MHz (205 frequencies)
■Power requirement: 9V ~13.8V (1.0 Amp)
■Operating current: 400~500mA
■Transmit power: 500mW
■Transmit range: up to 1,600 ft. (500 meters)*
■Frequency response: 20HZ - 15KHZ
■S/N ratio: 70dB
■Input signal: Stereo
■Output transmit signal: Dual mode: MONO / STEREO (user selectable)
■Operating temperature: 0 ~ 45 degrees Celsius (or) 32 ~ 113 degrees Fahrenheit.
■Power source: 100-240V A/C
■Audio processing limiter, Pre-emphasis: (75uS)
■Output antenna connector: BNC
■Buttons: Frequency (+), Frequency(-), Power, Memory 1, Memory 2, Mute, Transmit Mode (stereo/mono)
■Input/output - Jacks/Ports: BNC antenna connector, audio input (stereo 3.5mm), Microphone input (stereo 3.5mm), Power (DC)
■Display and indicators: Frequency, Audio mode (stereo/mono)

[wmilkie]

My 2 cents worth, from the least knowedgeable person here but,

I purchased the MBB 4000 last year, first year, and loved it. But it does transmit too far for me; about 0.5 miles in the city:

I contacted MBB, and asked them how to attenuate the output, and MBB , not me, recommended I drop the DC supply voltage from 12v to 9v. They told me the circuit is designed to operate in the 9-12v range. They didn't offer any numbers as far as range/signal reduction, but seems it would work.

I actually did not try it, but I will this year.

I did push the collapsible antenna down slightly(Don't know if this is a good idea or not) and the range dropped to about 1000 ft , still too much though.

[taybrynn]

http://www.edmdesign.com/orders.html

EDM is very good quality and sounds top notch.

[Guest guest]

wmilkie wrote:

My 2 cents worth, from the least knowedgeable person here but,

I purchased the MBB 4000 last year, first year, and loved it. But it does transmit too far for me; about 0.5 miles in the city:

I contacted MBB, and asked them how to attenuate the output, and MBB , not me, recommended I drop the DC supply voltage from 12v to 9v. They told me the circuit is designed to operate in the 9-12v range. They didn't offer any numbers as far as range/signal reduction, but seems it would work.

I actually did not try it, but I will this year.

I did push the collapsible antenna down slightly(Don't know if this is a good idea or not) and the range dropped to about 1000 ft , still too much though.

Actually in my instructions about the 33" telscoping antenna say to make sure it is EXTENDED FULLY or severe damage will occur to the transmitter.


Now, I have searched hundreds, if not thousands of pages trying to find a "Rubber Ducky" antenna DESIGNED explicitly for FM Transmitters with a BNC connector and being a straight antenna (not one with a 90 degree BNC mount, I did find a couple of those, but NOT what I wanted!)

I also ran across a Ham radio site that showed how to make a BNC antenna out of an old large sharpie marker body, BNC connector and a piece of wire that would be coiled around a pen, and then inserted in the sharpie body, but it was for 2 meter use. Again, not what I was looking for.

Anyone know what I'd need, and how I could "build" a rubber ducky type antenna that would work for an FM Transmitter?

Getting really frustrating trying to find one on-line after wading through all these sites and still NOT finding anything.


Or if someone has an old "MBB Rubber duck antenna" that they got with their Eclipse 4000 unit and want to part with it, let me know in a PM!

[MikeH]

Orville wrote:

Now, I have searched hundreds, if not thousands of pages trying to find a "Rubber Ducky" antenna DESIGNED explicitly for FM Transmitters with a BNC connector and being a straight antenna (not one with a 90 degree BNC mount, I did find a couple of those, but NOT what I wanted!)

Just wondering why it has to be a straight antenna? Is it possible to put a cable between the 90 degree antenna and the transmitter so it can be oriented towards the path you need?

MikeH

[Guest guest]

Orville wrote:

Actually in my instructions about the 33" telscoping antenna say to make sure it is EXTENDED FULLY or severe damage will occur to the transmitter.

Once again, it's about having a good match between transmitter and antenna...did it also say anything about only using the antenna included with the unit..?


Anyone know what I'd need, and how I could "build" a rubber ducky type antenna that would work for an FM Transmitter?

Forget trying to fab an antenna that will work. Use the antenna provided, and pad (attenuate) the output.

[wmilkie]

"Actually in my instructions about the 33" telscoping antenna say to make sure it is EXTENDED FULLY or severe damage will occur to the transmitter."

Thanks, I'll make a note not to do that again.
I'll try just dropping the supply voltage down instead to 9v and try that.

[Guest guest]

Actually in my instructions about the 33" telscoping antenna say to make sure it is EXTENDED FULLY or severe damage will occur to the transmitter.

Once again, it's about having a good match between transmitter and antenna...did it also say anything about only using the antenna included with the unit..?

This is basically all the Eclipse-4000 manual shows about that:

[align=left]Interchangeable External antenna. Optional Telescoping antenna or rubber flexible antenna are available. [/align]------------------------------------ END MANUAL INFO ----------------------------------

[align=left]Although the telescoping antenna is no longer optional, and wasn't when I purchased mine, otherwise I'd have the rubber ducky antenna and probably wouldn't even be having this conversartion..[/align]

[align=left]The info about the antenna needing to be fully extended came from an additional inset that was inside the box when I got the MBB unit stating:[/align]
[align=left]ADDENEDUM: ALWAYS FULLY EXTEND THE ANTENNA OR SEVERE DAMAGE WILL OCCUR TO THE TRANSMITTER. [/align]

[align=left](All in bold uppercase lettering just like that.)[/align]

[align=left]Anyone know what I'd need, and how I could "build" a rubber ducky type antenna that would work for an FM Transmitter?

Forget trying to fab an antenna that will work. Use the antenna provided, and pad (attenuate) the output.

[/align]

That would be all fine and well, but I really DO NOT like the antenna they supplied with it. I wish they had supplied the original rubber ducky type they were using initially for it. Then I wouldn't be looking for one!

However, I recontacted MBB about this again, and I will be purchasing one from them in a couple weeks. As they told me they could now get me one. They just need to send me the info on how to order it!

[travis p]

this is the antenna i use with my edm it is tunable i have the standing wave down to 1.1 to 1im using a old dell 3000 for my show computer with a creative sound blaster sound card the sound is better than a few local f.m.satations and for the price i could not build one cheaperhttp://www.fmdxantenna.com/proddetail.php?prod=14tun

[caniac]

Ok, I know this might sound like I didn't listen to good advice but I had already ordered the whole house transmitter before I read this.

Just tried out the Whole House transmitter today and to keep it brief it really sucks ass!!! Once I backed out of my driveway (10ft) the signal faded and was garbled.

1) I need something that is at least good for 50-100ft each way.

2) I do not nor do I want to solder anything (don't feel like burning myself numerous times - if I want to do that I will just stick my hand on the stove).

What are my options (that don't entail a second mortgage)?

[Steven]

caniac wrote:

2) I do not nor do I want to solder anything (don't feel like burning myself numerous times - if I want to do that I will just stick my hand on the stove).

What are my options (that don't entail a second mortgage)?

1. Buy an EDM-TX-LCD-EP for $190 + s/h.
2. Get your 6-year-old nephew to solder it for you.