From: misra@kitty.ksu.ksu.edu (Boo!)
Newsgroups: alt.radio.pirate
Subject: Fm Transmitter
Date: 6 Apr 1992 12:09:49 -0500
Organization: Kansas State University
Distribution: world
NNTP-Posting-Host: kitty.ksu.ksu.edu

----------------------------------------------------------------------
I saw a  post asking for FM transmitter information. Hope it helps. 
-----------------------------------------------------------------------
>From: flash@lopez.UUCP (Gary Bourgois)
>Subject: The RAMSEY FM-10 STEREO TRANSMITTER KIT REVIEW (Longish)
>                          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 practical 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
> 
>     Shipping add 6%.
> 
>                          Ramsey Electronics
>                          793 Canning Parkway
>                           Victor, NY 14564
> 
>                        (716) 924-4560 (Voice)
>                        (716) 924-4555   (FAX)
> 
>    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.
> 
>       
> 
>
>-- 
>=Marquette MI: It's Not the END of the world, but you can see it from here=
>==  Gary Bourgois flash@lopez (rutgers!sharkey!lopez!flash)  GWN UPLink  ==
>==  3.950  Nationwide Amateur Radio Nightly after 0200z=Learning Channel ==
>=============== WB8EOH = The Eccentric Old Hippie = WB8EOH ================