FM Transmitters

[Dinosang]

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!

[garyfunk]

The link you posted is bad, at least for me.

[Dinosang]

http://www.flowermoundchristmas.com/index.php/fm30bvedm

Try this!

[garyfunk]

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.

[Texan78]

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.

[hbomb341]

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

[Texan78]

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

[grump010]

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

[hbomb341]

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

[Dinosang]

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.

[Bubba in NV]

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.

[JeffF]

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.

-Jeff

[Guest wbottomley]

Jeff.... I use a laptop power supply. So far the results are 1000% better than the factory one sent with the transmitter.

[Guest wbottomley]

Here you go Jeff: http://cgi.ebay.com/Toshiba-AC-Adapter-PA3048U-1ACA-15V-Power-Supply_W0QQitemZ200255292271QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item200255292271&_trksid=p3286.c0.m14&_trkparms=66%3A4%7C65%3A1%7C39%3A1%7C240%3A1318

[Fred]

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.

[Texan78]

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?

[Fred]

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.)

[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.

[Gremler]

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

[Texan78]

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.