Ramsey FM-10 Info by mycal@netronix.com 4th Edition ----------- Here is a rough compilation of information about the Ramsey FM-10, and BA1404 Stereo FM broadcasters. It is in no way complete, nor do I take any responsibility for its accuracy. I know you haven't seen this statement but a 1000 times but here it is : For informational purposes only. I have been swamped with requests for information about amps, antennas and other mods for the FM-10, so I decided to dig through my mailbox and notes and compile this file. I hope It helps, and if anyone has more information about the FM-10 or FM transmitters, please send it to mycal@netronix.com -or- gallaghe@sonoma.vax.edu. I will try to update this file as new information arrives or is found out. A Postscript version with schematics and board layouts is also not out of the question. I would like to acknowledge the following people for the contributions and support: John Brewer -- brewer@anarky.enet.dec.com Alan Bryant -- uunet!csn.org!adb Greg Thornwall If I missed anyone, sorry, please drop me a note and remind me. FM-10 Mailing List ------------------ First Things First. There is now a mailing list that deals with the topic of the Ramsey FM-10 and other BA1404 based FM Stereo Transmitters. Feel free to join up and contribute. To send a message to the mailing list, send your question, reply, comment, or contribution to : fm-10@dg-rtp.dg.com To add or delete yourself from the list, send a short message with the function (add/delete/change address) along with the relevant e-mail address to: fm-10-request@dg-rtp.dg.com If you have any questions I can be reached at myca@netronix.com. Once again I want to thank Ed Savage and the guys at Data General, NC for making this list possible. FM-10 Archives -------------- Yes it is finally here, message archives of the fm10 mailing list and a place to put/find schematics, reviews, stories, etc. related to the FM-10 and other BA1404 based FM transmitters. People can FTP into dg-rtp.dg.com with user "anonymous" and password "". In the fm10 directory you'll currently find two sub-directories: incoming This is writeable by everyone and this is where people should upload new stuff. msg-archives This directory will have files named according to the date they were last "sealed". The file "Current" is a running log of all EMail messages from the last "seal" date of the archives. Other Places to Look -------------------- alt.radio.pirate is another good forum to find or post information on these kits. Although you may not have pirate aspirations, many of the things talked about can benefit everyone. other places to scan, sci.electronics and the amateur radio groups. Recommended Test Equipment -------------------------- An SWR/Power meter is a giant help, a CB to 2 meter one will suffice. Power readings will not be accurate, but can be useful for peaking. The most important part is the SWR meter, this is very important when making an antenna. Ramsey's Address ---------------- If your looking to purchase a FM-10 kit and can't find one locally try : Ramsey Electronics, Inc. 793 Canning Parkway Victor, New York 14564 Phone (716) 924-4560 Fax (716) 924-4555 Ramsey FM-10 70mw output amplifier ---------------------------------- Provides almost 9db gain to bring the output power of the Ramsey FM-10 Stereo transmitter from 8mw to 70mw. Not the best design, but all parts can be found at Radio Shack! +12v | / \ R1 *220 ohms(1/2 watt) / \ R2 9k | C2 -/\/\/\/-----------||-----> output | / | / | | / C1 | |/ <----------mps2222a (276-2009) in --||------|\ -or- 2n4401 ^ | -> -- | | | gnd currently on board * you can also use 2 440 ohm 1/4 watt resistors run in parallel I built this thing right on the underside of the FM-10 kit, C1 is the cap that currently goes to the RCA ant jack, the 9k and the 220 ohm resistor have to be bought, note that if you cannot find 220 ohms you can make one by using 2 440 ohm resistors in parallel, and that a 10k will work in place of the 9k but yealds poorer performance (-5%). Note that you can lower the resistance of the 220 ohm resistor to about 200 ohms for more power, but do not do this unless you can check to see if the transistor has gone into oscillation. The mps2222a is from Radio Shack part number 276-2009, use this part! if you substitute it for a 2n2222a you will get only half the gain. Be very careful to get the leads in the correct orientation! I have found that a 2n4401 can be used in place of the mps2222a with a little better performance, about 5mw more. I think the 2n4401 can be found at Radio Shack too. C2 is of the same value of C1, I took the one that goes to the on board antenna pad. Important! the value for R2 that seems to be optimal is 205 ohms, but it is very close to the sat point, If the amp. seems noisy (interferes with the TV etc.) back this value off to 220 ohms. If you lower this value below 200 ohms the power meter may read higher power but this will not be true, the transistor will be spewing all kinds of junk and the power meter will mistake this for higher output (in reality the signal we want will drop considerably.) Well that's it, effective range with a good antenna should be a little over double. ------- On Wed, 1 Jul 1992 13:16:47 -0600, "Alan D. Bryant" wrote: > The second stage idea didn't appear to do anything here, but I don't have any > measuring equipment, so it may have been a small enough improvement that I > couldn't detect it. > Hmm, very interesting, I haven't tested it in the real world, just with a HP power meter and spectrum analyzer. Also note that using a 2n2222a I could only get 30mw, but when using the mps2222a I got 75mw. This was all into a 50 ohm load, with a mismatched antenna it could actually degrade performance. I was kind of amazed when I calculated the optimal Rl and found it to be 52 ohms for that circuit. > I've been playing around with antennas a little myself. Made up a weird > concoction I'll have to describe to you at some point. No real test results > from it yet. I would like to hear about the details of what you have come up with when you get it all up and running. The $19 RS CB power meter would probable come in handy for doing antenna and power tests, It would be a lot better than nothing. ANTENNAS -------- Also Do you have a good antenna? I think that is the most important thing that you can do for extended range. I built a 1/4 wave ground plane using a UHF connector and 5 lengths of copper plated brazing rod (found at the local welding shop). Works great and only cost $3 dollars to make. use the formulas out of your FM-10 manual 234/freq=length of rod. insert the 4 ground plane rods in the 4 holes of the UHF connector, stick them through about 1/4 inch and solder. Solder the radiator in the top of the UHF connector (you may have to grind it a bit to fit.) Then bend the ground plane rods to a 45 degree angle to the radiator. There you have it a very effective antenna, just connect with a 50 ohm cb cable to your amplified ramsey, stick the antenna in a tree or in another high place and you should have 1 miles of solid coverage (when using the above amp.). Also If you have an SWR meter you can cut the rods a little longer and start clipping the ends off a little until you get the best SWR reading. | | | | = brazing rod | | | | | ----- ----- ----- = UHF connector | - | / - \ - | | / \ | | / \ The final antenna should look like this: | | // \\ That is 1 radiator pointing strait up and 4 ground plane radials. Be careful when you bend the brazing rod, don't break the connector. Grab the rod right below the connector with a pair of vice-grips (or the likes) and bend the brazing rod at that point. I have been told that you can shorten the radiator and make the ground radials longer to lower your radiation angle, but I haven't tried this, nor do I know what this would do to the antenna impedance. On The Road ----------- Old magnet mount CB antennas can make great mobile antennas, just take all of the base load out of them and cut the radiator to 1/4 wave length. If you need a longer radiator than the one that comes with the antenna use the above mentioned brazing rod. I've tried this antenna and it works great! It rivals my di-pole at home and you can drive to a high, optimal location for your broadcasts. You could also try a 5/8 wave length antenna, this would give you 2+db gain, or almost 2x power gain on transmit. Filter design for FM Radio Transmitters. ---------------------------------------- It is very important to have a clean signal, the way 99% of all people who get busted for illegal transmitting is that the people that live around them complain about interference. Do not do this, keep everyone happy, including yourself, be clean. When you amplify a signal, you get unwanted byproducts these are called harmonics. The show up at multiples of your starting frequency. For example if you amplify a 50mhz signal you may get echo's on 100mhz, 150mhz 200mhz, 250mhz... If you walk on your neighbors TV, the local fire depart- ment, or anyone else, you are going to get nailed. If you are only on the FM Band, you will hardly be noticed. ... I have looked into the filter design more, I have come up with these two: (basically scaled from the charts in the ARRL handbook). Filter Design: 7 element Chebyshev I run @ 88.1 so my 1st harmonic is 176.2 This filter seems ideal. Fc 3db 20db 40db 85.8mhz 95.9mhz 116mhz 148mhz .132uh .152uh .132uh -----()()()-----()()()-----()()()----- | | | | <-50ohm - 33pf - 68pf - 68pf - 33pf 50ohm-> - - - - | | | | -------------------------------------- | --- - Filter Design: 5 element Chebyshev Not as good as above, but thrown in anyway. Fc 3db 20db 40db 81.8mhz 105mhz 147mhz 222mhz .128uh .128uh -----()()()-----()()()----- | | | <-50ohm - 30pf - 62pf - 30pf 50ohm-> - - - | | | --------------------------- | --- - The tuff part in the above is winding the coils. 3t of #12 wire 1/2" diam should be about .12 uh. 4t is .17 uh. (but ugh, #12 wire is big stuff). I may just make all the coils 3t, and bend them around a little while watching the analyzer. Maybe use var-caps too. Well I will build this weekend and try Tuesday. I will let you know how it goes. mycal Very simple filter. ------------------- .15uH from fm10 >------()()()------> to antenna | | - c1 - c2 - - | | --- --- - - 88mhz 102mhz 107mhz c1 62pf 54pf 50pf c2 62pf 54pf 50pf its basically a scaled down version of the other filters. it won't knock the harmonics down as much as the other two designs but the good thing about this one is that it uses standard off the shelf parts. the inductor is one of those molded jobbies that looks like a resistor so you can make this very small. use the above cap values depending on which freq range you want to operate at. ie. if you run 87-90 use the 88mhz vals, 90-103 use 102mhz vals, and above that use 107mhz vals. use fixed value parts! .... I built the 7 element Chebyshev, I substituted .12 uh inducters for the .132 and .15 uh for the .152. Also I put 10-50pf var caps in place of the 33pf's and 10-90pf varcaps for the 68pf's. After a bit of tweeking I got -45db on the 2nd harmonic -55db on the 3rd -65 on the 4th, every thing else was off the scale. That is much better than -25db,-27db,-30db,-40db... -40db off the fundamental is required by FCC. [Actually the fcc says no more than .7mw out on any harmonic when dealing with VHF equipment, that's on top of the -40db requirement. But if you are running 1 watt out -40db is .1mw] I have found that peeking (buy tuning the var-caps) for maximum power output into a 50ohm load will give you close to maximum attenuation on the harmonics. Also the Fc can be raised or lowered quite a bit, I tried +-10Mhz (of 88Mhz) and could tune the Fc there. I am going to stick with the .12uh and .15uh inductors because I can get them for $.25 apiece at HSC, But I may try winding my own later on, especially if I use it on a high power output device. These molded inductors don't look like they can handle much power, but I have run 2 watts through them without problem.. On a side note, I don't think the Q of these inductors is that high, I think that if you wound the above mentioned #12 coils you would have a higher Q, hence, greater performance on the filter. On a second try I built another filter using variable inductor cans, and used fixed caps, this one seemed to have better performance than the last one, it was also much more stable. Var. caps are not very stable, so I would recommend using fixed caps. [Also of intrust is that the FM-10 puts out about 8-9mw and the 2nd harmonic is -25db off. The FM-4 Kit by ramsey puts out 130mw and the 2nd harmonic is only -12db off, which means the 2nd harmonic of the FM-4 is about as powerful as the FM-10.] FM-10 Myths ----------- 1) The fm-10 puts out 100mw of power. This is not true, or at least not true for the Ramsey FM-10's that I have tested. They put out between 8 and 15mw when driven with a 12volt supply. 2) The fm-10's output can be cranked up by reducing the value of R9. This like the above is not true. R9 and R10 are optimized for maximum output and greatest harmonic suppression at 12volts. There are much better ways of getting more output power than to mess with this output stage. FM-10 Improvements - -------------------- (Some from ACE magazine.) Stereo Pilot Mod ---------------- One of the first problems experienced with the FM-10 is difficulty in getting the stereo pilot to operate correctly. One solution is to replace C7 and C8 with a 38khz crystal, this works the best and is recommended. If you cannot find a 38khz crystal, you can make your life a whole lot easier with a couple part changes. As indicated on the Ramsey schematic, about 110pf is necessary to tune the oscillator. The components supplied to achieve this are a small fixed value capacitor (C7) abd a slightly larger value trimmer (C8). Since proper setting of the trimmer occurs within a very small 'window' (about 5% of the trimmers range), it can bet difficult or impossible to adjust the pilot to 19khz and have it stay put. This can be cured by increasing the value of c7 to 100pf and replacing c8 with a 6-50pf trimmer (Radio Shack #272-1340); a 5-30pf trimmer will do the trick. The RS trimmer will not fit the holes in the pc board; one needs to cut the leads off a spare resistor and solder them to the legs of the trimmer (just use bits of wire) to mount it on the component side of the board. Crystal Mod ----------- old set up new setup c8 c1 xtl where c1=10pf and xtl=38khz |-||-| |-||-|\|-| | c7 | | | v8=var cap |-||-| | | c7=cap | | | | Remove C7 and C8, replace with 38khz crystal and 10pf cap. Note that the 10pf cap and the crystal are running series and the old cap setup is running in parallel. Note: there have been good and bad reports on using the Epson crystal from digi-key. From what I have heard the crystal is quite delicate, and in at least one case the experimenter destroyed the crystal. In one of the positive case c1's 10pf cap was replaced by 2 22pf caps run in parallel, this yealded a rock solid stereo. Treble Boost Mod ---------------- Treble boost (pre-emphasis) improvement. The FM-10 appears to have been designed by someone outside the United States since it operates at the European audio standard of 50 microseconds. Receivers in the US are set up for 75 microsecond de-emphasis. R3 and R6 determine the time constant for the pre-emphasis curve. Replacing them with 75K ohm resistors (standard value 68K ohm is close enough) will result in improved audio response. A much better pre-empasis/input circut is shown in the July 1992 issue of "Radio Electronics". Not only do they use 75K ohm resisters in there pre-empasis, but they filter stray RF signals by inserting a .001 cap between pin 1 (of the BA1404) and ground, and pin 18 and ground. It has been noted that the above mod may actually cause distortion on cheaper stereo receivers, since they were mass produced for the world market, they were designed for the European audio standard, which Japan and other Asian nations use too. Try it out, let me know what works for you. Anti-Drift Mod -------------- There has been quite a bit of discussion on the FM-10's frequency stability. Complaints that digital receivers cannot lock onto the FM-10's signal for any great length of time. I have used the below mod with good results (I used an N750 negative temperature compensated disc), but I have been told that Mylar or Polystyrene caps are even better. The FM-10 was designed to be inexpensive and cost-saving measures with components are inevitable. Disc ceramic capacitors are less expensive than silver-mica caps, and also much less stable. Simply replace c16 with a silver-mica, tantalum or negative temperature compensated disc (say anywhere from N150 to N750) cap of the same value. ============== ============== ============== Other Raw Info ============== ============== ============== the 2sc2570 is supposedly replaceable with an ecg10. Also I have used an MRF901 for a replacement, but it yealds 2.5mw less output. The MRF239 can be used aas direct replacement for the Ramsey 2 meter PA kit. Cost is around $14 bucks. ~From: Greg Thornwall Mycal, I called the company that produces the BA-1404 chip. The company is the Rohm Corp. in TN. They sent me some interesting data on the chip: some electrical characteristic curves, list of distributors & representatives, application diagram and some similar block diagrams that comes with the FM-10. If you want any more info just write or call them up and they will send it free! Their address & number is: Rohm Corporation Rohm Electronics Division 3034 Owen DR Jackson Business Park Antioch, TN 37013 PH: (615)-641-2020 (ask for someone who deals with the BA-1404) FAX: (615)-641-2022 Also they have: PO Box 1399 Antioch, TN 37011-1399 --Greg (KD3SU) 38Khz Crystals.... > > Does anybody have any idea where to find 38KHz crystal (H-18). > > Don't know what a H-18 is, but you can use a C-2 type quartz crystal > for 38.000KHz by Epson America, Epson part number C-2 38.000KA-P, which can > be ordered, for example from Digi-Key Corporation (1-800-DIGI-KEY), Digi-Key > part No. is SE3314 Thanks Andrew, I've got the DK catalog H-18 is a solder welded case and C-2 is a cylinder type. I don't know if there is any difference in specs between them. Aaron B. ... ~From: Greg Thornwall I have some more stuff on another company that sells "pirate" electrical kits. Panaxis productions, PO Box 130, Paradise, CA 95967-0130 (916)-534-0417 ($1.00 for a catalog). They have a bunch of FM & AM transmitters from 20mW to 10W! They only sell PLANS for the high power transmitters here to the US and will sell kits for export elsewhere. They have a PLL FM oscillator (500mW) for sale in kit form for $129.00 (better stability!). ~From: uunet!toad.horizon.com!kevin (Kevin Criqui) Sorry for the delay - been super busy at work. The address I have for Panaxis Productions is PO Box 130, Paradise, CA 95967-0130. The phone number is (916)534-0417. My catalog has a $1.00 price printed on it, but I think they're $2 these days (still a bargain). I'm going to send my 2 bucks and get a new copy and see what fun stuff has been added. My little station consists of the "MMC1" Macromod Compander set for 2:1 compression, connected to the "SG" high performance stereo generator connected to the "FME" PLL FM exciter. Besides the Panaxis stuff, I have a homebuilt mixer console and of course, the 1 transistor PA. Prices from my catalog (which is likely to be out of date) are: Code Plans PCB P+P full kit ---- ----- --- --- -------- MMC1 12.00 18.00 26.50 87.00 SG 15.00 13.50 26.50 105.00 FME 17.50 15.00 24.50 129.50 While looking for my Panaxis catalog, I ran across a catalog from Communication Concepts, Inc. that has kits based on some of the AP Notes in the back of the Motorola RF devices data book (another must-have). They have a couple of 300 watt (!) kits that cover the 10-150MHz range (AR305 and AR313). There's another article (AN1037) that's a 300W amp specifically for 88-108MHZ FM broadcast use (but CCI didn't have it in their catalog back when I got my copy). CCI is at (513)426-8600 or (513)220-9677. ... ~From: gdavis@griffin.uvm.edu (Gary Davis) Many responded that they want to know more about the Oregon Comm Sys line of stereo PLL Fm transmitters. Here is their address and phone number: OREGON COM SYSTEMS 1257 Siskiyou Blvd Suite 132 Ashland,Oregon 97520 TELE: 503-271-3294 Models are stereo, 100mw output,PLL frequency syntehsis. Some come with audio mixers also. All are wired and tested. This would appear an ideal unit for driving a linear amp. Harmonic output is not specified,however low pass filter designs are not difficult. They also stock antennas. The FM units are rated with an audio response of 10 to 15 kilohertz +/- 2 db. Frequency coverage: 88-108 mhz RF output 100 milliwatts Frequency Stability +/- 100 hertz Response (audio) 10 hertz to 15 kilohertz +/- 2db Input level: 500mv cost: $109.00 Delux stereo models 149.95 ------------------ ------------------ Well I have more info, but it is not organized enough even for this rough sheet. Given time I will polish it an post it. Once more If you have any info, I stress "ANY", about this subject please drop me a byte or two. have fun, mycal@netronix.com Mycal Johnson _ mycal@netronix.com | |_ _ _ There is only one (707)769-3309 | | | | |__ nor-cal ----------------- | ___\ so-cal - - - - \ / mycal Ban all Bans | | WB8EOH Gizmo Report (Very Long) The Ramsey FM-10 is a low power FM stereo transmitter kit that is easy to build and has many practical applications around the home and ham/swl shack. After living with one for several weeks, I could never go back to life before I acquired this little "freedom machine". The audio quality and stability of the signal give the unit many HI FI type applications, and indeed I am already planning to buy another unit to patch into the Audio/Video system. Egad, you mean you have to BUILD this thing? When my XYL saw that this package I had spent fifty bucks on consisted of a couple of polyethylene bags full of plastic bugs and little metalic button like pieces, she shook her head in dismay. Though I tinker with computer and radio gizmos all day long, I will admit that the past 20 years have seen me become an "appliance operator" more content to sit back and PLAY than get in there and tear into the circuitry, much less build something from scratch. Well, the folks at Ramsey have honed the art of kitbuilding, and even a klutz like me CAN have the satisfaction (like in the old Heath ads) to say "I built it myself". Constructing the FM-10 was in part a happy trip down memory lane. In my distant youth, one of my happiest memories was the construction and operation of an Allied Radio Knight Kit #83Y706 three tube AM Phono Oscillator. This wonderful little gadget paved the way not only for my interest in Ham radio, but also got me interested in broadcasting, a field which put bread on the table for many years. Well in the more than 30 years between the two kits, things sure have changed. First right off, don't even think about dragging out the old Weller soldering gun and the old roll of Kester solder. First thing I had to do was borrow a low wattage iron, and get some super thin solder. The Lifetime Supply of solder I bought in 1968 (five pounds) was fine for antenna work, and gobbing up audio connectors, but the old stuff is actually WIDER than many of the separate connections on the FM-10 PC board. EGAD these components are TINY. Kudos to Ramsey for the way their whole concept. The manual is very well written. My only problem was I did not get the companion booklet on how to build a kit (the generic HOW TO SOLDER book). Well I hoped that the instructions that came with my 1957 Knight Kit still applied, because I remember them. Heat the component, don't glob it all over the place, and try not to melt the PC board. I was on my own to develop a technique. Ramsey even takes this into account by having you mount some of the larger "landmark" components first, namely three RCA jacks (left and right audio and the antenna jack). Now I wanted this thing to work. I would not be able to face Elaine if it became necessary to send the completed unworking mess back to Ramsey for their $18 an hour bail-you-out plan. So I took absolutely extrordinary steps. With a (borrowed) digital meter, I measured every resistor, even though Ramsey gives the color code for each one in the manual as you install it. One of the nicest touches is the GIANT print of the PC board, upon which you place all the components in the same place they will go in the final kit. I did this with most of the components, except for the multitude of .01 capacitors, which I left neatly together (Ramsey uses a masking tape type type medium for keeping similar value components together). The scariest moment for me was soldering in the 18 pin DIP socket that houses the heart of the kit, a ROHM stereo transmitter on a chip. We are talking TEENY TINY little pins separated by seeming microns. EGAD. After each dot of solder, I held the PC board a quarter inch from my eyeballs to make sure there were no solder bridges. And I measured all the components with the Digital meter a second time before installing each one. You probably won't take these extrordinary steps, which make the simple kit an all night project. But it was a FUN night. The scent of melting tin/led/rosin... The occaisional absolutely PERFECT joint... Kitbuilding is not only an art, it is positively a cosmic experience. It is relaxing, creative, and there is the anticipation of all the wonderful things you will do with your kit upon completion. 3:25AM Ah. The moment of truth. Connect the nine volt battery, push the power switch, and TUNE around on the FM radio to find the carrier. And I found....... NOTHING. It did not work. Now this is where we separate the men from the boys. How well you manage not to throw the thing through the window. So I went back through the whole manual. checked EVERY joint. Eyeballed EACH component. I could find NOTHING wrong. Elaine came into the shack as I was holding the PC board. I hated to admit defeat. But I told her it did not work.... yet. She held the board and looked at it with wonder. She could not believe that I had placed each of the little parts in their places. She told me I would figure out what was wrong with it. The next day, I went through the manual again. I took voltage measurements, and found all the proper voltages on the chip and RF amplifier. I was stymied. Then I looked very closely at the OTHER side of the board. I stared at the ROHM chip, which Elaine had called a "train trestle". Hmmm. I wonder if I pushed on the chip if it would go in any farther. Push. Click. It snapped into place. I pushed the power switch, turned on the FM radio, and found a nice clean carrier at 102.3, with the stereo light blazing away in pure clear silence. Hot DAWG it WORKS! First thing I did was to move the frequency. Since it was transmitting on top of one of the local stations, this seemed in order. Ramsey's manual stresses the importance of selecting a clear channel so as not to bring the wrath of neighbors and the FCC. Up here in the boonies, there is a tremendous clear swath from about 98 Mhz to 102 mhz. (I plan to pouplate it). The next thing required is adjustment of the subcarrier frequency and stereo balance. Surprisingly mine was already right on for the subcarrier adjustment, and I found out that this adjustment is actually pretty critical. There is a test point if you have a freq counter to get it exactly on 19khz, but it can be done by just turning the little variable capacitor until the stereo light goes on. The "stereo balance" control takes a bit of explaining. This is not a simple LEFT-RIGHT adjustment, but actually adjustment of the level of left MINUS right. It is more of a separation adjustment, and also seems to have a real effect on tonal quality. It took quite a bit of diddling to get it right, and there seems to be some interaction between the two controls, as the stereo light will go out just when you think you have the sound right... The end result is a surprising quality signal with amazing separation. However, one thing to make note of... The RM-10 is designed with NO audio level controls. This is a bit of an oversight, because when using it with components that have fixed level output, the unit is prone to overmodulation. You MUST be able to lower the audio level of whatever it is you are feeding to the tranmitter, as it is too sensitive with EVERY component I tried connecting direct. Once you get the level under control, though, it actually sounds better than many local FM stations because the signal is not run through all sorts of "Enhancers" that broadcasters use to be the loudest thing on the band. I did find though that adding an audio limiter (an old DBX 119) really helped tame the overmodulation problem. I finished the project by mounting it in the $12.95 Ramsey Kit cabinet. OK, this is where the Ramsey guys make a few bucks. It does give the kit a finished look, but I would have to say that this is a bit dear for a simple plastic case. I think the next one will be built into a VIDEOTAPE plastic case or other cheapo cabinet. One oversight is that there is no hole in the cabinet for the whip antenna which mounts to the circuit board. Ramsey suggests constructing a dipole or groundplane antenna, which I did initially in the final installation in my hamshack. I have since stopped using this antenna however (more on why later) OK NOW WHAT CAN I DO WITH THIS LITTLE GADGET Ramsey gives many practi0al applications in the manual. I found the unit handy for listening to MDS stereo TV on a little sony walkman in the wee hours without having to run headphone cords. Remote listening of ANYTHING on your main stereo system in any room in your home by just tuning the radio is just ONE thing the kit can be used for. My own application is a bit unique. I have the FM-10 in my ham/swl shack, and it is connected to a stereo mixer, to which I have several receivers patched in. I am a communications junkie and often in the shack I listen to several things at once. The only problem is that one can not stay in ones hamshack all day long. Well with the FM-10 and a pocket stereo receiver, you can monitor whatever you wish in your home or yard. Now since the Ramsey Kit is a STEREO transmitter, you can do what I do (if you are insane enough) I have a 2 meter rig on the LEFT channel, scanner on the RIGHT channel, and the HF rig panned dead center. The ears and the brain manage to sort it all out. I feel sorry for any of the neighbors who happen to tune in when in this configuration (when I am in my active monitoring mode). No Code, No License, No Kidding It's LEGAL Now speaking of neighbors, lets focus for a moment on the LEGALITY of using this kit under part 15 of the FCC rules. In 1989, the FCC revised part 15, changing the way the measurements are taken to determine if a device is legal. The new standard is: 250 microvolts per meter. A calibrated Field Strength Meter is needed to make sure the signal complies with this regulation (FCC rule 15.239). Beyond this, part 15 requires that the unit produce no interference to licensed stations. Basically those are the rules. What you put on the device is YOUR business. It comes under the same type of regulation as cordless phones, baby monitors, and walkie talkies. the only difference is that this unit operates in a BROADCAST band rather than a semi-hidden part of the spectrum like the others. The Ramsey manual has a chart that shows that even if one complies FULLY with this measurement, the transmitter has a surprising range. Doing the math of the inverse square law, we find that there is still .41 microvolts at 5000 feet from the transmitter, nearly a mile. Since the Ramsey kit has a FINAL AMPLIFIER, it is much more powerful than a similar kit sold by another manufacturer which uses the chip output only (that one can be heard well within only 20 feet). I found that the kit with a dipole antenna cut to the operating frequency has TOO MUCH range for my own use. Those who wish to "Play DJ" might be interested in running the recommended dipole antenna (making CERTAIN they make the Field Strength Measurement) to get the maximum range out of the unit. I found that just a small piece of wire gives me all the coverage in my home that I need. For someone interested in providing a broadcast type service, to a college dorm, appartment complex or local neighborhood (Legally the signal can be quite loud over a quarter mile away) It can be legally done under part 15 of the present FCC rules (as ammended in June of 1989) by simply adding a mixer, microphone, and sound sources to the Ramsey Kit. An application I am considering is connecting the audio output of my new satellite system and tuning it to the BBC audio feed and just leave it run that way when I am not using the dish for other purposes. This way I can enjoy BBC in FM quality and so can my immediate neighbors. Now before the flames begin, please remember that copyrights, etc, do not apply to part 15 transmissions. You can put on ANYTHING you want. Just as if you were listening on closed circuit speakers. The only difference is that your immediate neighbors CAN also enjoy the transmissions as well. FCC RULE 15.215(a) Says: "Unless otherwise stated, there are no restrictions as to the types of operations permitted under these sections." This general provision *APPEARS* to leave you free to use the fm transmitter for just about ANY type of operation you desire, including becoming a "legal low power broadcaster". Now the nitty Gritty: RAMSEY FM-10 FM STEREO TRANSMITTER KIT Price: Circuit Board and Components -- $29.95 Cabinet (black plastic) -- $12.95 Order From: The Radio Collection Box 149 Briarcliff Mannor, NY 10510 (914) 923 1862 o Operates from internal 9 volt battery o Choice of onboard whip or external antenna o Stable output, from 88 to 108 MHz o Left and Right channel RCA line audio input jacks o Use with Mixers, cassette or CD decks etc. o Clear, step-by-step assembly instructions o Helpful information on FCC rules included TYPICAL USES: o Extension of home stereo system without wires o Student-operated school radio station o Home or neighborhood radio station o College dorm favorite music broadcast service o Listening aid for auditoriums, churches NOTE1: I am in NO WAY affiliated with Ramsey Electronics other than being one of their very satisfied customers. NOTE2: If you plan to use the kit as a "broadcasting" service, I would STRONGLY SUGGEST you have the output level CERTIFIED by an engineer assertaining for SURE it is no more than 250 microvolts per meter. This kit has an almost amazing range, and I imagine it could very easilly exceed LEGAL SPECIFICATIONS if you are not careful.