Yet Another FM-10 FAQ..
Experiments,mods,and projects for the Ramsey FM-10,among other things.

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The Ramsey FM-10 isn't the greatest transmitter/exciter,but it can be improved upon quite a bit,to atleast resemble something decent.
It was a great learning experience for me though.It has inspired me to read,re-read,build,and experiment quite alot.

1!. Ditch the ceramic caps!,they suck.Get ,foil,mylar,dipped mica,etc..(use a high quality oscilator cap,or trimmer!) *anything* but ceramic!
Use high quality audio input caps,The de-emphasis caps are most important,but upgrading the 10uf coupling caps can help also
(This can improve sound quality/stereo pilot stability alot.)

2. use some silicone to "tack" glue the crystal to the board.( I used super glue...heh,whatever works for some vibration control..)

3. Metal enclosure,forget the plastic case they sell,it's nearly useless. ( I made a box from copper PCB that I soldered together,it works okay,but could be better.) Ground it to the enclosure well,and connect everything to a good earth ground.
If you are homebrewing,a dual sided circuit board,with 1 side being a full ground plane might help a bit aswell.

4. Make sure you have a well filtered/regulated power supply. I put a 7812 regulator on the underside of the board.I also added more filtering capacitance for kicks. (Using free Sanyo Os-Con samples!)Also,you can replace the diode string for the BA1404 with a regulator,just don't go over 3V!

The above "mod's" made it more stable.(Kinda necessity,more than mod,IMO.)
You can also ditch the balance control, replace it with a 50K resistor. If it isn't exactly centered,it can screw with the stereo pilot,and stability.(put it across the two pins on the chip,don't use the + connection,as you would on the potentiometer.I havn't actually tried this yet,but this is what the data sheet says.)

Also,it tends to be overdriven easily.Changing the level potentiometers helps a bit.I believe mine are 10K.(I think 1K are "stock".)
A note on changing/moving level controls,etc,Using excessive wire length for anything can result in noise,instability,feedback,etc! I advise that you keep all parts closely soldered to the board,and for example,don't move the level controls to the front panel with any length of wire.
Reducing the treble of the input signal helps also.High frequencies tend to screw up the 19khz pilot tone.Anything over 12-15khz should be cut.
I did the well covered 70mw mod. Tack soldered a 2N2222/2N4401 circuit on the underside of the board. Got 70mw output. covered a fair area(half mile radius),with a 1/4wave vertical groundplane antenna hanging from my bedroom ceiling. Not bad!
 

The schematic of the 6AK5 amp can be found HERE

(Courtesy of Fred Nachbaur.You can see his website HERE)
So far I have built two of these! (I'll post pic's,eventually)
The power supply voltage can be upped a bit for more power,but can shorten the life of the tubes.
I had to use a voltage doubler supply to get a solid watt.With the stated voltages I only got about 500-700mw,Your mileage may vary here.
For the power supply,I used a small dual primary transformer (configurable for 120/240V) and used one primary for power input,and the other was rectified and filtered for B+.(in the doubler circuit.)The transformer also has 2,10V,600ma windings I currently have both regulated,one for filament power,and the other for bias.I plan to paralell them for 1.2A,and drawing filament,and bias from a single point.
For the coils,I used a Sharpie pen as a form (~12mm.dia),and used #16 solid wire.I believe the input coil was 4 turns,and the output was 5 turns,with 1 turn over it.  (you'll need to move the 1T coil side-to-side a bit for max power.Over the "cold" (B+) end of the coil seems best.)
To tune up: Adjust bias for lowest setting (fully negaitve) peak input for highest reading on input jack,peak output cap for highest reading on output,retouch input a bit,done!,Go broadcast some tunes,and sip a cold one. :-)

I'm currently working on a mobile powersupply,and hope to have some higher power versions soon.I'll post updates.