The Compact Synthesized PLL FM Kit -10mW and 100mW versions
Posted on March 12, 2006
From our old site There has been new FM PLL Kit showing up on ebay these days, so I grabbed one and gave it a try. The product web page is http://www.edmdesign.com/intro.htm Overall impression – great to play with, might be frustrating for a beginner. The version without a case or power supply needs both and should be considered a kit. Be prepared to do some assembly.
From our old site There has been new FM PLL Kit showing up on ebay these days, so I grabbed one and gave it a try. The product web page is http://www.edmdesign.com/intro.htm Overall impression – great to play with, might be frustrating for a beginner. The version without a case or power supply needs both and should be considered a kit. Be prepared to do some assembly.
Features:
Compact size
Microprocessor Controlled
Easy Frequency Programming
Digital Frequency Readout with 7-segment LED display
Non-Volatile Memory
Transmissions from this unit can be received on any reasonable FM radio MONO or STEREO between 87.7 ? 107.9MHz
You must be able to find a fairly quiet spot in this band to operate the unit otherwise range and stereo quality will be affected.
When assembled, this kit is a digital synthesized unit (meaning no frequency drift, tuning or fiddling). Frequency is phase-locked against a accurate and stable quartz crystal (similar to the one in watches) This unit’s frequency is programmed by means of a CMOS microprocessor without any DIP switches and complicated look-up tables. Pressing the UP or DOWN buttons makes it very easy to set the frequency. Transmit frequency is clearly indicated on a 3 digit, 7 segment LED display.
Frequency response: 20Hz – 15kHz
Level: Line-level input via RCA type sockets
Stereo Separation:
Typically about 40dB
Operating Power Requirement:
Needs a clean regulated 12v DC source with current capacity of 150mA for the standard power and 250mA for the high power option.
Operating the unit with an un-regulated wall wart type transformer will introduce mains hum into your transmissions.
I set up an “instant OTR outlet” using a completed 10 mW PLL XMTR kit, a guitar compressor for a little punch and a CD player for program input. I pushed it all out through a simple dipole.
Total cost was $100.00, $70 for the transmitter kit, $20.00 for the compressor and $10.00 for the CD player.
The primary problem in setting up this system was that the transmitter kit needs extensive post purchase work to be useful. That’s not a criticism, per se, as it is only $70.00 and it’s and otherwise nice unit – just be aware it’s a kit and not plug and play.
First, it must be mounted in a metal box, as the circuitry has no protection from stray signals.
Second, you need a real clean power supply or you will be slammed with ripple. I’ve been using Eveready lantern batteries until I could build a clean enough PS.
Range is a bit too much for comfortable Part 15 use, I’d probably add an antenna attenuator to knock the range down a bit if I was going 24/7. I was getting a car radio range of about 3000 feet north-south, and 2000 feet east-west. Portable radios couldn’t pick me out of the cross talk on the band as well, and I got about half that on the portables.
This transmitter is also available in a 100 mW kit unit for $100.00 – Probably a guaranteed bust if left running for any period of time
UPDATE: EDM Designs FM 100 Mw Transmitter Kit with case.
The New 100 Mw kit, completed and mounted in its case
I ordered this thing on Friday last week. Wednesday the following week I got the kit in the mail. Nicely packed, easy to assemble, easy to get the transmitter installed in the case, included a power supply to use after assembly.
I got the whole kaboodle to avoid blowing the thing up by plugging in the wrong kind of AC adapter by mistake (it’s happened).
I immediately sorted through the FM dial to find 3 adjacent channels that were clear – remarkably, I found them.
I plugged in the long wire they include with it, and away I went. A short time after opening the box my kit was assembled and I was listening to my radio.
The design is rugged. The box has mounting ears and 4 screw holes.
There is an RCA jack for the antenna, 2 for the stereo input, and the power supply plug.
I don’t know what else to say other than : Wow. VERY nice.
And for people who are wary of buying from overseas: this was shipped from the EDM affiliate in California.
I most definitely give this bad boy 2 thumbs up.
Kit Assembly Instructions from EDM
Basic summary of assembly steps
We are often asked about the skill level needed to get a unit completed and operational. Below is a quick summary of the steps to be performed by the buyer to get the unit functional. More detailed instructions and precautions about static sensitive devices, polarity etc. will be provided in the manual.
Remove microprocessor from protective foil and insert into socket holder on PCB
Insert digital displays into respective sockets on PCB
Connect the power wires to a suitable 12VDC source.
With the EP versions, install the supplied power connector and fasten with screws
Solder the power wires, Red and Black to power terminals on the power connector
For versions without enclosures, you may construct your own enclosure or purchase from another supplier
For versions without power units, you may construct your own or purchase from another supplier
Follow operating instructions supplied for specific model series in manual
