FM TRANSMITTER REVIEWS
Past & Present
   I have tested the FMX and the EDM LED side by side; The FMX is like a Yugo while the EDM LED is like a Toyota...

The EDM LED transmitter is an outstanding value when compared to Ramsey and others.  Low harmonics and spurious emissions will reduce the chance of a visit from the FCC...

For the money the EDM LED is the best transmitter in regards to sound quality, signal quality & innovative design when compared to Panaxis & Ramsey...

For those who want to set up a part 15 FM station on a budget, I suggest the EDM LED transmitter and a Yamaha MG-10/2. The MG 10/2 includes 2 XLR mic inputs and 4 stereo inputs; all inputs include 3 band EQ, aux send which can be had for less than $70 on e-bay. Total cost around $187, compare that to a Ramsey 100B kit priced around $269...

Add a Behringer DSP-1424P two band processor for under $100 and listen as your EDM LED transmitter takes on the best sounding FM station you have on the dial.

Unfortunately the LED transmitter is no longer available from EDM due to the discontinuance of several key parts used in the LED. EDM has replaced it with CS version; which uses the same case and display as the LCD version.


EDM DESIGN
INSIDE LOOK AT THE EDM LCD TRANSMITTER
EDM DESIGN
Radio Brandy Home Page
EDM DESIGN
   The EDM LCD FM transmitter is a bit larger and heavier than the older LED version, unlike other transmitters using LCD's the EDM is strictly for frequency display. Other transmitter tend to use two or three buttons and display to adjust everything from audio & power levels to mono/stereo etc; the EDM LCD uses trimmer pots to set power level, L/R audio & MPX levels. I prefer this method; as it's easier to finely trim levels with trimmer pots. RF power is adjusted two ways: A switch determines max output; either 10 or 100 milliwatts and a trimmer is used for fine adjustment with a range from 1-100 milliwatts. Audio & RF connection are RCA and the 12 volt DC input is a 2.1mm connector (center positive) so you can unplug the old EDM LED and plug in the LCD. NOTE: Holes in the case allow easy access to audio trimmer pots and channel up/down buttons.

The EDM LCD transmitter is an easy to assemble kit; which includes plugging in the IC chips into their sockets, solder DC connector to PC board and mount the LCD display to the main PCB. It takes about twenty minutes to complete assembly. The end result is a rock solid FM transmitter that out performs all other transmitters in its class; yes even the older EDM LED version. Improvements include better low pass audio filtering which is designed to improve Stereo operation and offer even deeper bass and separation. The RF is also cleaner with improved filtering and a lower noise floor.

The price for the EDM LCD is about $210 including shipping and insurance. The EDM LCD FM transmitter is delivered with a compact switching power supply, a wire test antenna. A RCA to BNC adapter is available at low cost. The EDM LCD FM transmitter remains a great value when compared to the Ramsey FM30b or FM100b which are kits where you have to assemble everything.

On a score of 1-10; the EDM LCD FM transmitter is an easy 12. We remain sold on EDM for a number of reasons, First quality:  the EDM transmitters are solid performers in every way, I have even drowned one while it was on the air! Dried it out, fired it back up and it went right back on the air. Second delivery: From the time the transmitter is ordered to the time it lands on the doorstep is within a week no matter where you live on the planet. Third: customer service is second to none, e-mails are responded to right away, even after I killed my first one, I had it back on the air in a week where it remains three plus years later. I have a second EDM LED as a back up; it has been on the air twice for less than an hour while I dried out the other one.
INSIDE THE EDM LCD
FM TRANSMITTER

Spec Type

LED Series

LCD Series

Notes

Frequency Range (87.7 - 107.9) MHz (87.7 - 107.9) MHz 0.1 MHz increments (click)
Frequency Stability < 0.0005% < 0.0005% Of set frequency
Frequency Accuracy < 0.001% < 0.001% Of set frequency
RF output (standard) 10mW (+10dBm) into 50O 1-100mW into 50O  
RF output (high) 100mW(+20dBm) into 50O   Switchable 10/100 mW
RF output LCD   1-100mW into 50O Adjustable 1-100mW
RF muting during tuning period -20dBc < -30dBc RF reduced dB below carrier
VSWR Withstand 20:1 Withstand 20:1 No damage
Phase noise (dBc/Hz)     Commercial VCO's specs
1 kHz offset -84dBc/Hz -97dBc/Hz in the range 87-108
10 kHz offset -90dBc/Hz -117dBc/Hz for comparison
20 kHz offset -94dBc/Hz -125dBc/Hz (click here for more)
100 kHz offset -104dBc/Hz -137dBc/Hz  
Residual FM 14Hz (300-3kHz) BW <1Hz (50-15kHz)BW LCD VCO vs HP RF gen
Incidental AM <0.2% <0.1%  
RF Harmonics out 10mW (-30dBc) 100mW(-50dBc) -60dBc or better  
Spurious Output -50dBc or better -60dBc or better  
SNR (Signal-Noise-Ratio) 60dB or better 75dB or better  
Audio Distortion (%THD) 0.3% @ 1kHz 0.1% @ 1kHz Or better @ 75KHz deviation
Stereo Separation 28-40dB @ 1kHz 30-45dB @ 1kHz Limited by stereo encoder chip BH1415, BH1414
Audio Response 20 Hz - 15 kHz 20 Hz - 15 kHz  
Max Input Level
(RCA line)
500 mV rms 500 mV rms (Click here for more info) make
Max Input Sensitivity 100mV p-p 100mV p-p  
Power Requirement Clean Regulated 12V Clean Regulated 12V PSU must be regulated
  150mA for 10mW operation 250mA  
  250mA for 100mW operation    
Antenna Needs 50O - 75O impedance 50O - 75O impedance 1m wire antenna supplied
Transmit Range Range will depend on various factors like, location, interference, type of receiver etc. 10mW unit (300-400)ft
with good receiver
Due to continuous product development, EDM reserves the right to change any specification without notice
THE SPECS
EDM Design
Radio Talk Forum
Older kit version of the B/W 1 watt module
Surface mount version of the B/W 1 watt module
Ramsey FM30b review
Ramsey FM25b review
10-09-11