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FM Transmitters


Dinosang
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I have read a lot of hipe about the EDM Transitters on how good theyn are so I decided to look into it. I listened to a sample of the EDM compared to the Ramsey from http://www.flowermoundchristmas.com/index.php/fm30bvedm


I must say I was impressed with the EDM! But listening to the the noise on the Ramsey brought me to the conclusion that the power supply used on the Ramsey must be poor. Now I do not own the Ramsey but I do own a unit from China that you can get from Ebay which is less expesive then the EDM & Ramsey and it comes assembled! The reason I mention this unit is because it has the same buzzing noise you hear from the Ramsey, but as my Description states How to Improve Signal to Noise Ratio. The power supply has to be very clean or the noise just gets passed on to your FM signal. I have made my unit from China transmit with no noise at all in fact it was so clean I could hear the high frequency of my RDS encoder and I had to turn the output down to 10% to eliminate the RDS noise. Now before you go run out and buy a really good low noise power supply just try this first to verify your transmitter is not total junk. Use the cheapest and cleanest DC power supply ( A BATTERY) You will find the buzzing and humming noise dissapear and realize that your transmitter is not junk after all, but your power supply is! We tend to spend a lot on a unit and then we scimp on the power supply. If you choose you can use a larger battery and use it to power your transmitter all the time just remember not to leave the charger on while playing. Hope this helps and have a noise free Christmas!

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Not that in the test the EDM wasn't impressive. But I agree with the first post. It sounds like a problem with the power supply on the FM30 which is creating the noise. Almost like it is not properly grounded. Also I would like to see this tested again with a different FM30.

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Texan78 wrote:

Not that in the test the EDM wasn't impressive. But I agree with the first post. It sounds like a problem with the power supply on the FM30 which is creating the noise. Almost like it is not properly grounded. Also I would like to see this tested again with a different FM30.

The test was with a straight from a pre-build manufacturer (Won't be named) - multiple power supply were used that was the BEST of the worst. After we took it all apart there were physical problems with how the unit was assembled. But the test was for prebuilt. I can tell you even using other FM30's the EDM win's hands DOWN.

Harrison
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Has this test ever been done in other locations? Ramsey units might be more sensitive to electrical interference. Even if it is, that is still a bonus for EDM since electrical interference doesn't effect the unit. I would like to see how the EDM sizes up to the transmitter I use. It has worked great for me and is very clear and it comes assembled as well. It would be nice to conclude and could help others what exactly causes noise to signal. I know wind can play a subsantial part in signal espeically on low power units. I like how that EDM can be mounted though. That is a nice plus for at least me.

http://www.canakit.com/direct-access-synthesized-pll-stereo-fm-transmitter-export-only-kit-ux100-ex.html

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When I built my FM30 a couple of years ago, I had a terrible hum. Upon investigation, the contact between the PCB and case was a little loose. I inserted 4 small lengths of wicking braid between the case and PCB and the transmitter has been rock solid ever since. Just thought this info would help others with any hum problem.

Cheers
Daryl B

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grump010 wrote:

When I built my FM30 a couple of years ago, I had a terrible hum. Upon investigation, the contact between the PCB and case was a little loose. I inserted 4 small lengths of wicking braid between the case and PCB and the transmitter has been rock solid ever since. Just thought this info would help others with any hum problem.

Cheers
Daryl B

It is VERY common!!!

Harrison
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garyfunk wrote:

Ahh, I see. there is a space on the end of your first link. The space should not cause the error on the server but it does.

Yes that is weird It was to late to edit the post so I resent it. Have you tried a battery hook up the audio will impress you I am sure.
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I have the Ramsey FM25B. Yes the power supply really sucks. I put two ferrite chokes on the power line. One right out of the transformer, and one at the end right before the plug. Now you have to crank up the volume really loud to hear the hum. I actually had to turn the seperate volume input pots down a little bit and the sound was better. All my radios lock right on to the signal. (103.9) Using the telescoping whip out of the top of the case I actually had to change the output voltage so I would only transmit within a 1/2 mile radious.

I am very happy with the Ramsey.

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Just wanted to add that I have one of those Chinese VASTELEC transmitters and after a little tweaking, even that sounds good. I added a much better power supply, grounded the case, and added a low-pass filter on the RF(so there's no stray signals interfering with anything important) and it sounds as good as the other FM stations in my area. (there is a slight hum when no music is being transmitted and volume is turned *way* up, but during normal broadcasting you can't hear it)

I think most modern transmitters that aren't absolute garbage *can* sound good if you listen to what they are telling you. :P

-Jeff

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I think there must have been at least two versions of the FM30 produced by Ramsey. The one I purchased in 2008 was called a "FM30B". The kit came with a ferrite bead for the power supply, and was equipped with spring-loaded contacts to ensure good ground contact between the PCB and the metal case. I've been very pleased with its performance. (And, being an ex-sound man and engineer for the past quarter century, I'm pretty critical.)

Maybe after the rush of light-up season is over I can drag the unit to the test bench where I work and come up with some non-subjective measurements. But, judging by the schematic of the 30B, I doubt any any of these measurements will disappoint me.

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Jeff Millard wrote:

Fred wrote:
I think there must have been at least two versions of the FM30 produced by Ramsey.

I'm sure there have been many revs since the 30 came out. My transmitter is also an FM30B, however it is about two years + old. The issues that caused me to abandon it as my primary show transmitter had nothing to do with the buzz. That didn't start until recently, and was cleared up with the use of a higher quality power supply. This thread gives a little insight into my problems with the Ramsey, and why I would most assuredly point someone to Taybrynn's EDM to get the music out to the cars.

Jeff


That is interesting. So are the Ramsey's the only ones that use the Gal5 and is the problem only isolated to the Ramsey?
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Jeff Millard wrote:

Fred wrote:
I think there must have been at least two versions of the FM30 produced by Ramsey.

I'm sure there have been many revs since the 30 came out. My transmitter is also an FM30B, however it is about two years + old. The issues that caused me to abandon it as my primary show transmitter had nothing to do with the buzz. That didn't start until recently, and was cleared up with the use of a higher quality power supply. This thread gives a little insight into my problems with the Ramsey, and why I would most assuredly point someone to Taybrynn's EDM to get the music out to the cars.

Jeff


Jeff, thank you for the information. After reading that thread, I started getting a little paranoid. (I don't have a backup transmitter.) So, I started looking into what it might take to add a little ESD protection to a 30B. I figured I'd start by checking to see if the manufacturer of the GAL5 might have some app notes on the subject. Just one problem - I'm having trouble locating the manufacturer. Do you think the GAL5 might actually be the GALI-5+ found here: http://www.minicircuits.com/pdfs/GALI-5+.pdf

(Appologies for getting off-topic here. But, my curiosity is killing me.)
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Dennis Cherry

This being my first year to have my own display, I needed a transmitter, after reviewing many posts on many forums I bought the EDM transmitter.

I have not heard the sound quality of either the EDM or the Ramsey units until later this year, I heard two Ramsey units that other members have used for a couple of years, both sounded like AM transmitters with AC hum and poor sound quality.

Now after the test that HBomb did comparing the Ramsey with a EDM and the comments made by others afterwards, it is apparent that many others have had the problem with the Ramsey Buzz. and did not know any better or how to fix it.

I think we have improved the sound quality of our displays this year buy having the EDM units available and helped others fix the Buzzing of the Ramsey units with either replacing the power supply or improved antennas.

Just my 2 cents worth.

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Fred wrote:

Do you think the GAL5 might actually be the GALI-5+ found here: http://www.minicircuits.com/pdfs/GALI-5+.pdf

It sure looks like him, and specs look right too, good job finding it, I tried and couldn't find it either. I think I might buy a couple of these and try them out.



Jeff Millard

Why don't you send me back the FM30, I sure would like to know whats going on with it, and I'll get it back to you ASAP. I am sure you can use a backup.

Bill
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Ramsey owners still outweigh EDM users. Not to dismiss EMDs quality up to now, but compared to Ramsey, EDM owners are few and fair between and Ramsey has been widely used for years. So with that said you have a few years under the Ramsey belt. The poll is still out on the EDM because it hasn't had enough use yet. Some people have had no problems with Ramsey while others had. EDM hasn't been used long enough to see any problems. So I wouldn't just dismiss Ramsey all together. It has and still is a solid transmitter for some. Different strokes for different folks. I don't own ether but I am interested in both.

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I like my Ramsey, have had it for years and would compare the audio quality to a broadcast station. The comparison done at the texas mini was not an accurate representation of an FM30 (a properly assembled Ramsey transmitter don't sound like that). Being pre-assembled means nothing, Ramsey only sells kits, who ever assembled that one did a poor job.

As long as one follows proper ESD precautions (don't touch the antenna with out grounding your self first), and it will last for years.

I however have a TM100 antenna with the whip removed and a grounding block in line and would only have it that way.

Using a set of rabbit ears for the transmitter antenna is only asking for a blown output......

Bill

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Bill, the only problem is that they don't all sound like yours. Harrison and many other TCL members bought professionally built units and some were skillfully assembled by members ... and many (NOT ALL) sounded just like Harrison FM30B. His test was demonstrating how some percentage of units sound, not all. But if you want to infer that he had the worst Ramsey in Texas and then tested it to make EDM look good ... thats not the case and why would he want to do that? Harrison only wants whats best for others ... I know that from talking to him. Like you, he helps other members with his own time and money ... for the good of others.

Nobody is saying (or even claiming) Ramsey transmitters can't be good or are not serving most members well. They largely ARE. Like anything sold in large volumes, you also get more stories of complaints and troubles.

That said, once upon a time ... there were other big players (i.e. panaxis) and then along came new player Ramsey ... the market finally figured out the Ramseys were good and certainly better than the late model panaxis units which were crippled for Part15 operation and they didn't offer kits the way Ramsey eventually did.

The EDM transmitters have been around for 7 years. In that time, it's mostly been the original EDM LED that was sold. In the last 1 to 1.5 years, the EDM LCD replaced the LED as the flagship transmitter ... with a number of incremental improvement made to the LED going into the LCD design.

The EDM LED is still sold and is quite a bargain in terms of price vs. performance.

I can tell you that the TOTAL number of failed EDM units in those years is far less than the number I've simply read about from fellow members on the this and other Christmas forums. But in fairness, there are many more sold.

So when I went looking for my FIRST transmitter, I discovered many pirate radio boards ... and after reading PC and LOR forums ... I expected Ramsey to be all the rage. But to my surprise, they were talking about EDM's ... EDM who? So I could tell that EDM was known in certain circles (broadcasting) and not in others (light shows).
I took a risk on the EDM, bought it and was blown away by its good performance. I then tried to get group buys so our users could discover this product that could be useful to our endeavor. I think as Dennis said ... it's a good thing for the hobby.

I can tell you that Ramsey doesn't post specifications on their units. EDM does. Ramsey has a one year warranty and EDM has a two year warranty. Draw your own conclusions (if any) from that. That doesn't mean Ramsey is bad. We all know you can fix its shortcomings, if they appear at all ... and have a great transmitter.

Even the founder of Ramsey (John Ramsey) is now off selling his own transmitters ... but I don't know anything about them. http://ramseytransmitters.com/

Now keep in mind that EDM is a S. African company and their currency (the SA Rand) is in the toilet and has been for a long time (never recovered after international sanctions were lifted after apartheid ended). THeir exchange rate against the dollar when from 6:1 to 8:1 in just the last 12 months alone.

So my take is that these units are priced so competitively because of this currency conversion that makes their units very affordable right now.

Yes, it is a tiny company and no comparison on sales between Ramsey and EDM.
You similarly can't compare sales and infer superiority or inferiority based on that.

When I discovered this amazing product earlier this year, there was virtually nobody here using the EDM. Maybe a few at most. Ramsey is and was the defacto standard for FM transmitters in this hobby. I don't think thats a bad thing. I just think a few folks tried something new this year and got lucky because the EDM was a dark horse that could really run. EIther way, Ramsey and EDM as so much better than the other alternatives (and there ARE some dud brands out there).

I can tell you on paper, you might say the Ramsey and the EDM use the same chip ... so same performance, right? Well, not exactly. Ramsey (apparently) took the chip manufacturer specs and implemented per them. EDM actually tried to see if they could enhance the performance beyond those specs and was successful in doing so.

On the subject of the GAL, EDM recognized and publicly has said they know of these problems ... so they purposely used the older generation chip, which was proven to be realiable and free of the problem related to the GAL. Being a software developer myself, I value INNOVATION and thinking outside the box -- to make something better. I saw EDM doing this and they might be rewarded for it someday.

The power supply on the EDM, IMHO is better ... but that said, most folks reading this could find a better one and yes ... a better power supply does help any transmitter sound cleaner. But the power supply is only a fraction of the reason why the SNR on the EDM is so good.

The way EDM takes care of customers ... only reminds me of a few companies. One of them is LOR. With a customer is always right focus ... EDM and LOR are winners in my book. From most stories I've heard, Ramsey is also a first class company as well with excellent support.

Scott

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I agree, like I said and you touched on. Ramsey is widely owned and a lot of people have them, so the problems will be more from Ramsey owners since they are the majority used. So you will hear more people having problems with them because they are so widely owned. EDM is still making it's niche in the market as far as Christmas Displays go. So the problems if any, you won't hear about at all and few it any. EDM shouldn't be discounted as a good transmitter just because they haven't been around and you shouldn't discount Ramsey ether because of all the problems you hear. That is because Ramsey is widely owned as mentioned. I am sure as EDM becomes more popular and is more widely used there flaws will come out as well. Only time will tell. I have a very solid transmitter nether Ramsey or EDM, but I would like to try out the EDM and if it is no better then the one I have. Then I have an extra, but I do like how it can be mounted in my sound rack which is a bonus.

Do these EDMs have an option for a external antenna?

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The EDM has an RCA connector for the antenna ... so you can convert to just about anything you have on the antenna side. Typically that might be a RCA to F-con adaptor. But no, there are not any antennas are pre-sold with them or for them specifically.

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Dennis Cherry

EDM announcement today:

Good news! As of the beginning 2009 we will be extending the warranty
on any EDM transmitter to 3 years!

Our products have been very reliable and in the past year we have seen
very, very few comebacks or failures. Some of these were probably due
to misuse by the end user or problems with a 3rd party power pack. This
will apply to new and previous sales. We believe that not many other
competitors can make this claim or are willing to risk such a bold
move.

We have confidence in our product designs and want to pass that on to
you, our customers.

We have customers with some of the very first EDM LED transmitters
still running after 7 years of constant use.

EDM Team

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