Ramsey FM-10 Info
[Document Version: 10.2]
[Last Updated: 3/26/96]
Author : Mycal
E-mail : email@example.com
Latest version from ftp://netacsys.com/pub/web/mycal/fmfaq.html
This file is Copyright (C) 1993, 1994, 1995, 1996
by Mycal <firstname.lastname@example.org>
I grant free copying rights via BBS's, USENET, Internet FTP sites.
Distribution via printed media or CDROM requires the author's prior
Once more If you have any info, I stress **ANY*** about this subject please
drop me a byte or two.
Have fun, email@example.com
Here is a rough compilation of information about the Ramsey FM-10, and
other BA1404 Stereo FM broadcasters. Some of the modifications may make
your BA1404 based broadcaster illegal to use on the open airwaves in the
US and Canada. Also it has been brought up that the stock Ramsey FM-10
kit may exceed FCC power limits when used with a proper antenna.
The information contained in the file is in no way complete, nor do I
take any responsibility for its accuracy. With that in mind, along
with the above paragraph I must say:
THIS FILE FOR INFORMATIONAL PURPOSES ONLY
THIS FILE FOR INFORMATIONAL PURPOSES ONLY
When I first started hacking on my FM-10, a few of us on
were exchanging information on mods to improve the range, stability and
audio quality of the FM-10. After a couple of posts about filters and
amps, my mailbox was swamped with requests for copies of previously posted
information and other questions about the FM-10. So rather than drive
myself crazy with sending a piece of info here and there, I decided to
dig through my mailbox an notes and compile this file. I hope it helps.
Also if anyone has more information about the FM-10 or FM transmitters,
antennas, mixing equipment, programming information, stories about pirates,
or anything else that falls into this realm, please send it to
firstname.lastname@example.org. I will try to update this file as new information
Also I am working on a some Postscript files that will contain instructions
on how to build some equipment that is to complex for ASCII art. You
might want to check the FTPable archives every month or so.
I would like to say thanx to all the people that contributed to the
information in this file. The list has grown quite long, and some
of the contributors would like to remain anonymous. So for now I am
going to forgo all the names, if this is not up to your liking please
let me know.
Yes it is finally here, message archives of the FM10 mailing list and a
place to put/find schematic, reviews, stories, etc. related to the FM-10
and other BA1404 based FM transmitters. Currently a 350mw amp plan,
800mw amp plans, "Radio is my bomb" text, slim jim plans/info and
the BA1404 spec sheet are located there.
People can FTP into dg-rtp.dg.com with user "anonymous" and password
"<your e-mail address>". In the fm10 directory you'll currently
find three sub-directories and a file:
This directory contains:
- amps/ - 800mw.zip, amp_5-40W, fixed.ps.Z, mycal350.ps.Z, and mycal350.zoo
- antennas/ - jpole antenna kit (software and documents), 3-meter Slim-Jim plans
- ba1404-specs/ - TIFF files with official specs
- CPP-Holland/ - Projects (amps, PLL-circuits, Stereo coders, SWR-meter, etc)
- misc/ - min-radio-station kit, stories/news-clips, projetcs, etc.
- incoming/ - This is writable 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
- "FM10-FAQ" - older version of this FAQ
The info packet has evolved yet again, it is now 50 pages. It includes
plans for 4 amps, a 200mw, 350mw, 800mw, and 5watt. Instructions for
modifying the Ramsey PA-1 for FM broadcast band operation. A section
on how to design and build your own antenna. Plans for a power meter,
regulated power supply, and dummy load. A block diagram showing a
typical station. Spec sheet for the BA1404. FM-10 modifications.
Sources for parts and info. And a more up to date design of my digitally
synthesized transmitter. Loaded with schematics, board-layouts and diagrams.
Plus, schematics and construction details of the FRB 5 watt transmitter.
And now compressor and limitor plans, FCC facts and reality, DIY media
The price for this packet is $10 in the US and $12 overseas.
Address to send the $$ to is:
You can also use this address to send me any info that would be hard
to send by email. I will trade info packets for hard copy information,
email me for details.
- PO Box 750381
- Petaluma, CA 94975-0381
Note: this packet is in a constant state of change, more info could be
added at any time.
is another good forum to find or post information on FM
radio transmitter. Although you may not have pirate aspirations, many of
the things talked about can benefit everyone.
Other places to scan,
and the amateur radio groups.
Rick Harrison's FTP site containing a low power FAQ and a part 15 FAQ
can be found by FTP'ing to site
ftp.std.com and looking in the directory
Free Radio Berkeley now has an archive on CRL. It can be accessed by
FTP'ing to site
ftp.crl.com and looking in the directory
The American Radio Relay League (ARRL) has a useful service -- the ARRL
Information Mail Server. This is an automated mail server that let's you
access many of our information files, containing information about various
facets of Amateur Radio. Some of the information has technical value
that is related to all radio services.
To use it, send a mail messages with the word:
in the body of the message to:
This will give you all the information you need to use this service.
A little zine that sometimes discusses pirate/micropower radio along
with public radio stuph. Send frank a buck to help out with the
copying and stamps. Very Good, and now available in Electronic form.
E-mail Frank at email@example.com for details.
- Frank Haulgren
- PO Box 3038
- Bellingham, WA 98227-3038
- 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.
A NOTE on power meters. I recommeded the above power meters because they
are inexpensive and most people that are interested in hacking a FM-10
have very limited funds. These are by no means accurate, but they will
give you some idea what is going on. If you can spend the money you
can get an accurate power meter that is designed for this band, but the
cost is 10-15 times more.
- A rf probe could also be used as a replacement for a powermeter,
construction details below.
- A 50ohm non inductive load is also very helpful, for low power applications
a 50ohm 1/4 or 1/2 watt carbon resistor works well. This can be used to
tune up your kit and amp without interfearing with anyone. Also note that
you can run as much power you want, legally, as long is it doesn't radiate.
- A VOM is also very helpful. High I would put out the extra bucks and
buy one with a freq counter (if you shop around, about $60-$70). Buy
the one that covers audio to 20MHz(or more). If you are serious about
electronics you need one of these!
Dummy loads are great for testing, without radiating a signal. In fact
you can run as much power as you want into one of these things legally!
Basically you want to create a non-inductive 50-ohm load. This can be
done with regular carbon resistors, or by buying pre built Amateur or
CB radio loads. For low power ( <.5 watt ) an ethernet terminator works
well (check temp when using if it gets very hot lower input power, if it
is still cool you may be able to go up to .75 watt)
Most CB loads use a 2-watt carbon 50-ohm resistor.
You can build your own, as wimpy or as studly as you want by running
resistors in parallel to create 50-ohms. ie, 2 100 ohm 1/4 watt resistors
will create a 1/2 watt 50 ohm load...
Do not use 50 ohm wire wound resistors, they are not 50 ohms at radio
---------\ Sample Dummy Load where -****- = 50 ohm
---|--****-- / mounted in UHF connector. carbon
For those of you (like me) who are in constant Starving Student
mode, and DON'T have a good Scope, you can use a good DMM for RF power
calculations. All you need to do is build a RF probe. Here's the
schematic: (Yes, taken from 1989 ARRL Handbook)
--probe tip-----||-+---/\/\/\-------to center of 50 ohm coax.
.01uf | 4.7M +------to braid
--- diode |
cliplead for gnd---+-------------+
Anyway, the diode should ideally be
a Schottky diode (low rf capacitance). Although a 1n914 will work.
To use, just hook up to your digital Meter, set on DC voltage.
You will get very close to RMS RF Voltage. (this probe was specified for a
10Meg Ohm meter).
To calculate power into a KNOWN purely resistive load (a.k.a. a dummy)
where e is the RMS RF voltage, R is resistance :-)
This is also useful for checking inputs and outputs of low
power RF units, since the inexpensive power meters don't seem to do real
well below 1watt.
I've been talking to a few ppl that are worried about there "voice" being
on the air, since they are afraid of being recognized.
So I dusted off the old stacks of Radio-Electronics and found two articles
that may be of intrest.
In the January 1993 issue they have a "build your own digital voice
changer" using a simple Real time digital signal processor. I think that
this design is very simalar to the voice changing telephones. It basically
raises or lowers your voice pitch. A place called LNS Technologies @ 1-800
-886-7150 sells the kits for $59.
In there September 1992 issues they have a "build this dsp voice-effects
board" using a little more complex, programmable, real time digital signal
processor. The software they include contains a harmonizer, echo, reverb,
and pitch. The kit is sold by American Disributors Inc for $105 @
1-800-877-0510. You can also write your won software but the programmer
is several hundred $$.
DC electronics has a Robot Voice Kit for $15. I don't know how well this
works or what it sounds like, but it clames to be adjustable for many
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
- Tel: 1-716-924-4560
- Fax: 1-716-924-4555
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! Much better designs are available at the archive
If you want an updated,
[GET]. If you don't have
\ R1 <strong>*</strong>220 ohms(1/2 watt)
=== <strong>**</strong> F2
R2 9k | C2
<strong>**</strong> F1 === C /
| | /
C1 | B |/ <----------MPS2222A (276-2009)
in --||--+---|\ E -or- 2N4401 (better)
^ | -> -+ -or- MPS918 (best)
currently on board
* you can also use 2 440 ohm 1/4 watt resistors run in parallel
** Optional but recommended, Ferrite beads, help prevent oscillation,
and help the amplifier produce more gain. Slip over one end of the
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 yields poorer performance (-5%).
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. The MPS918 can produce up to 150mw.
C2 is of the same value of C1, I took the one that goes to the on board
Important! the value for R1 that seems to be optimal is 220 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 240 ohms. If you lower this value below 205
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
Well that's it, effective range with a good antenna should be a little
The Ramsey 2-meter amp (PA-1) can be converted for use on the FM
broadcast band. The following changes need to be made:
- L1 - should be replaced with a 1-turn 1/4" diameter coil, identical
to the stock L2 shown in the PA-1 manual.
- L2 - no change required
- C1 - no change required
- C2 - should be replaced with a larger trimmer capacitor. Use a trimmer
that will go up to at least 125pF.
- C3 - no change required. At higher power levels (>15 watts), this capacitor
should be replaced with a trimmer that goes up to at least 200pF.
- C4 - should be replaced with a larger trimmer capacitor. Use a trimmer
that will go up to at least 125pF.
Tuning the amp for proper operation on 3-meters can be tricky. I
suggest the following setup:
FM xmitter -> SWR Meter -> PA-1 -> Power Meter -> 50 ohm dummy load
Starting with C1 and C3 about 1/2 turn from closed, tune C2 and then C4
for maximum power output. If the SWR is much over 2:1, you will need
to adjust C1, C2, and C4 to reduce it to an acceptable level. Watch
the output power while you do this. Sometimes, tuning the trimmers for
minimum SWR will peak the power output, whereas other times the power
output will drop markedly. Avoid trimming the capacitors that have a
large negative effect on the power output. After several iterations of
adjustment, you should have decent power gain and low input SWR.
Note: Watch for sudden jumps in power output that you can't linearly
tune through. If you encounter this happening, chances are your
SWR between the transmitter and amplifier will go way up, too.
This is a sign that your amplifier is oscillating and you will
need to tune it out of this region for proper operation.
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.
Remember good antenna will improve you range much further than a good amp
into a bad antenna. So this should be your 1st project to increase your
use the formulas out of your FM-10 manual 234/freq=length of rod.
- 234/88Mhz = 2.66 feet * 12 in/feet = 31.9" -or-
- 234/108Mhz= 2.17 feet * 12 in/feet = 26"
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
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:
// \\ sky ground --horizon--
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.
- That is 1 radiator pointing strait up and 4 ground plane
radials. (sorry for this extreme description, but there
has been some confusion.)
Try not to have anything metal near the radiator, this will effect
the radiation pattern. The radiation pattern should look a lot like
a doughnut surrounding the radiator, though deformed a bit.
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.
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 is better than my di-pole
at home and you can drive to a high, optimal location for your broadcasts.
Also with this setup you need very little coax cable. Line loss using
RU-58u can be killer @ 100MHz.
You could also try a 5/8 wave length antenna, this would give you 2+db
gain, or almost 2x power gain on transmit.
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. Most of this interference
is caused by harmonics. Filters cut down these nasties. So don't
draw attention to yourself, keep everyone happy, including yourself,
be clean, use a filter.
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 interfear with your neighbors TV, the local fire
department, or anyone else, you are just asking for trouble. If you are
only on the FM Band, you will hardly be noticed.
Many FM transmitters are designed without adequate filtering on the
output. Add to this the fact that most pirate radio operators lack
spectrum analyzers with which to tune up their equipment, and it is
easy to see that many stations are likely to be full of spurious
outputs. You're a lot more likely to attract the attention of the
FCC if you wind up interfering with all your neighbors television
sets because of spurious emissions than you are if you emit a clean
signal. While more elaborate 5- and 7-element filters offer greater
attenuation of harmonics, I have found the following design to be
simple and very useful. Furthermore, several of these filters may
be chained together in series to produce even better filtering [**]
If you make L1 with the 18 gauge wire as indicated and use capacitors
rated at 50 volts, the power handling capability of this filter will
be around 20 watts. If you use 100 volt capacitors, it should be
able to handle 50 watts or more. The insertion loss of the filter
is generally less than 1dB if you stay below the F(0db) point.
Here is a
for a 3-element lowpass filter:
input o---+---uuu---+---o output
| L1 |
gnd o---+---------+---o gnd
The following table summarizes 5 different variations of the 3-element
lowpass filter. I have constructed and tested some of these myself and
find that they work as advertised. The attenuation figures shown below
were produced by spice.
3-element Lowpass with ~50 ohms input/output impedance
C1 C2 L1 F(0db) F(3db) F(6db) F(10db) F(20db)
33pF 33pF Note1 113MHZ 138MHZ 163MHZ 200MHZ 320MHZ
39pF 39pF Note2 98MHZ 119MHZ 140MHZ 173MHZ 293MHZ
47pF 47pF Note2 95MHZ 112MHZ 130MHZ 160MHZ 270MHZ
52pF 52pF Note2 92MHZ 107MHZ 125MHZ 152MHZ 255MHZ
56pF 56pF Note2 90MHZ 105MHZ 121MHZ 147MHZ 246MHZ
62pF 62pF Note2 87MHZ 101MHZ 116MHZ 140MHZ 235MHZ
I constructed my filter in a tiny aluminum enclosure with female
chassis mount BNC connectors mounted for the input/output. I soldered
C1 and C2 between the center connector and ground on each BNC connector
and soldered L1 between the two center pins on the BNC connectors.
- 2 turns #18 wire with a 5/16 inch inner diameter. Wind snugly
at first. If SWR is objectionable, increase spacing between
coils a little bit at a time.
- 2 turns #18 wire with a 3/8 inch inner diameter. Wind snugly
at first. If SWR is objectionable, increase spacing between
coils a little bit at a time.
[**] You can make a 5 element filter using the above parameters by
using the following configuration:
input o---+---uuu---+---uuu---+---o output
| L1 | L2 |
C1- -C2 - C3
- - -
| | |
gnd o---+---------+---------+---o gnd
Were C1=C3, C2 = (C1 * 2), L1 = L2, and the C1, L1 values are taken from
the above chart.
[Also of interest is that the FM-10 puts out about 8-9mw and the 2nd harmonic
is -25db off the fundamental (frequency we are broadcasting on). The FM-4
Kit by Ramsey puts out 130mw and the 2nd harmonic is only -12db off the
fundamental, which means the 2nd harmonic of the FM-4 is about as
powerful as the FM-10. db is log10, ie 3db is 2 times 6db is 4 times...]
There have been several myths about the FM-10 kit, the most prevalent are:
- 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 about
8mw when driven with a 12volt supply. (Note: there has been several
revisions of the FM-10, it is possible that the original version put out
more power, but I find even that highly unlikely since it would require
another amplifier stage.) Also the FM-10 is the only low cost kit, that
I have seen, with an amplifier stage. Most others have power outputs
in the fraction of a mw area.
- 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. Lowering
the value of R9 will most likely degrade the FM-10's performance and cause
lots of interference.
Note : I sent this file and a list of other modifications to John Ramsey.
Low and behold 4 monthes later the FM-10a is released. The new FM-10a
incorporates the following mods marked with an '*'.
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)
and 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.
On a 2nd note: I replaced c7 with a 68pF cap and found it much easyer to
tune a rock solid 19KHz at the test point.
Better than the above 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: If you have an FM-10 you can call Ramsey and get this
mod for free!
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-emphasis/input circuit is shown in the July 1992 issue
of "Radio Electronics". Not only do they use 75K ohm resisters in their
pre-emphasis, 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.
Note: the FM-10a kit comes with both sets of parts so you can select
European or American audio standard.
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 NPO discs), 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 cap of the
same value. Even better is to cut the leads of the capacitor as short as
possible and mount it directly on the bottom of the circut board.
The FM-10 has two power grids, one is a low voltage grid to feed the
BA1404. This low power grid uses three diodes to drop the input
voltage to a safe level for the BA1404 which can only handle about
3.5 volts. Since the BA1404 contains the oscillator, and the frequency
it oscillates on is dependant on the voltage that is feed to it, if
you are feeding the FM10 with a non-regulated power source (ie a battery)
you can make it much more stable by replaceing the three diodes
with a zener type diode. Select a zener diode with a voltage value
of 1.5 to 3. Remove the three diodes that are in series. Insert
the zener diode with the banded end going to the low voltage + line and
the other end going to the system ground. Even better is to use
a voltage regulator like the 78L02 or 78L03, since zener diodes can
Another flaw of the FM-10 is that they don't stop the RF from feeding
back into the power supply. There are two 270 ohm resistors feeding
the RF outputs, one R13 feeds the output of the BA1404, the other R9
feeds the ouput of the amplifier. Inserting 1 to 10 uf chokes in
series with these resistors will help clean up the FM-10's output and
boost the power output by about 4mw bringing the FM-10's output to
12mw. Use the tiny moulded inductors that look like resistors, or small
homemade chokes wound on a small ferrite, not the big honk'n power filter
chokes that you get from RS.
The following is a list of sources for items used for modifications,
replacement parts, or other kits and equipment used in FM radio
BA1404s and other FM Broadcaster kits can be found at:
- D.C. Electronics
- Tel: 1-800-467-7736
- Tel: 1-800-423-0070
- Fax: 1-602-994-1707
They sell BA1404s for $2 a piece, seems to be the best deal going.
Also they Sell 38KHz crystals for $5.99, which is also a fair deal, the
crystals are tiny ones like the digi-key ones, but a different brand and
work without problems or the Digi-Key ones.
38KHz Crystals can be obtained by calling:
- 701 Brooks Ave. South
- P.O.Box 677
- Thief River Falls, MN 56701-0677
- +1-800-DIGI-KEY (344-4539)
- +1-218-681-3380 (FAX)
38.000 KHz by Epson America, Digi-Key part No. is SE3314
(see notes on crystal mod on using this crystal, also note that
this is a cylinder type crystal and kinda delicate. You are probably
better off getting the 38KHz crystals from D.C. Electronics)
Kits to let a thousand transmitters bloom. Lots of FM transmitter
and amp kits, mail, email or call for more info. Reasonable prices.
Can be slow to deliver (2 weeks to 3 months but promised to get better.)
- Free Radio Berkeley
- 1442 A Walnut St., #406
- Berkeley, CA 94709
- Voice mail: (510) 464-3041
- E-mail: firstname.lastname@example.org
Mouser Electronics Mouser Electronics Mouser Electronics
11433 Woodside Ave. 2401 Highway 287 North 12 Emery Ave.
Santee CA 92071 Mansfield TX 76063 Randolf NJ 07869
370 Tomkins Court
Gilroy CA 95020
Catalog Subscriptions: (800) 992-9943 (Continental US only)
Sales & Service: (800-34-MOUSER
(800-346-6873) (US, Puerto R., Canada)
Giant Catalog! 239pages of parts!
Just about everything.
No min order for north america.
$100 min for overseas.
- RF Parts (transistors)
- 1320-16 Grand Ave
- San Marcos, CA 92061
Just about any RF transistor!
- 2733 Carrier Ave.
- Los Angeles, CA 90040
- (800)325-2264 USA
- (213)727-0054 WORLD
- (213)727-6032 FAX
RF transistors and other
semiconductors + more catalog.
178pgs $20 min order
Panaxis Productions makes some very high quality FM transmitters. The
last word in Transmitting, tons of kits.
(Right next to my old place of study Chico State!)
- Panaxis Productions
- PO Box 130
- Paradise, CA 95967-0130.
Catalogs are $2, well worth it, a must have item.
A little taste of there catalog:
- MMC1 Macromod Compander for 2:1 compression
- Plans $12, PCB $18, P+P 26.50, Full kit $87
- SG High performance stereo generator
- Plans $15, PCB $13.5, P+P 26.50, Full kit $105
- FME PLL FM exciter
- Plans $17.5, PCB $15, P+P 24.50, Full kit $129
More expensive than a FM-10 but much higher performance.
A company called Progressive Concepts sells plans for a 88MHz to 108MHz
amp. The power curves show that 12mw in will yield 2.5 watts, but can
be driven harder for up to 12 watts. (I have not seen these plans)
Plans only in U.S., $16 (a bit spendy, ouch!)
- Progressive Concepts
- 1313 N. Grand Ave. #291
- Walnut, CA. 91789
If your looking to purchase a FM-10 kit (or a PA-1 kit) and can't find one
- Ramsey Electronics, Inc.
- 793 Canning Parkway
- Victor, New York 14564
- Phone (716) 924-4560
- FAX (716) 924-4555
Should be $29
- Rohm Corporation
- Rohm Electronics Division
- 3034 Owen DR
- Jackson Business Park
- Antioch, TN 37013
- Tel: (615)-641-2020 (ask for someone who deals with the BA1404)
- Fax: (615)-641-2022
Also they list:
- Rohm Corporation
- PO Box 1399
- Antioch, TN 37011-1399
the 2SC2570 is supposedly replaceable with an ECG10. Also I have used
an MRF901 for a replacement, though tough to mount, try bottom of the
pc board and connecting the whip antenna pad to ground plane. MPS901s
seem to replace the 2SC2570 directly, same case too, check the pinouts
though. I have also been told that MPS918s work well also.
The MRF239 can be used as direct replacement for the Ramsey 2 meter PA-1
kit. Cost is around $14 bucks.
Newark also has the 38KHz crystals for $2.90 ( I don't know Newark's address,
this was sent to me in the mail, will try to find it though.)