hey out there
I bought an Ramsey AMC1 transmitter kit and soldered it together
over a couple days. I connected a 9 foot piece of wire to the
rf out center pin in the rca jack and ran a short ground wire to
a cold water pipe. Long story short, the transmitter will broadcast
about three feet, and very quietly, meaning you can barely
hear the music going into the audio in. What is loud is a strong
hey out there
I bought an Ramsey AMC1 transmitter kit and soldered it together
over a couple days. I connected a 9 foot piece of wire to the
rf out center pin in the rca jack and ran a short ground wire to
a cold water pipe. Long story short, the transmitter will broadcast
about three feet, and very quietly, meaning you can barely
hear the music going into the audio in. What is loud is a strong
buzz that happens pretty far away from the transmitter on the
am radios that are tuned to the frequency the transmitter is
broadcasting at when it is turned on. Sometimes it goes in and
out, always on but louder then a little quieter in a cycle about
a second long. my soldering is OK, but its not perfectly neat
i dont think there are any cold joints. The rosin is connecting
a couple parts of the circuit but I didnt think the rosin center
of the solder would create bridges for electricty to jump around
on the circuit. The power source is a 12v wall wart, but this
isnt an annoying hum, its an overwhelming, pulsing hum
and the audio is barely there, and you can only hear the audio
when the antenna is almost touching the recieving antenna
of an AM antenna. Ive tried disconnecting the ground wire
from the pipe, used a diffrent gauge wire for the antenna.
Anyone please like to take a peliminary guess about whats happening
and what I start with?
Exasperated,
Mark D.
The hum you are likely hearing on the air is a product of the power supply and the audio input circuit.
First, use a car battery or regulated/filtered 12 volt power supply. The "wall-wart" is meant to be used only for testing. It has a poor filtering circuit and poor voltage regulation. Make sure you follow the set up instructions to the letter.
Next the wire antenna needs to be clear of all metal surfaces and objects, period. the antenna needs to clear of nearly everything else and oriented vertically. You should consider building the loaded antenna mentioned in the instructions. Most of the signal is remaining on the chassis of the transmitter. And that leads to the last possible problem.
The RF signal on the ground side of the chassis is causing the audio circuit to "motor boat"; a slow oscillation of the audio amplifier circuits. The RF energy is de-sensing the audio section causing the audio to go in and out. Am transmitters operate by significant audio level driving the modulator. Make sure your audio source has enough audio output to drive the transmitter to full modulation.
Until you get a better, more stable power supply, better DC filtering, a somewhat resonant antenna, better isolation/decoupling for the audio circuit you are going to continue with a fairly common problem with Ramsey AM transmitters. I have an AM 25 and in the beginning it did the same thing. I changed all the previously mentioned items and it improved quite a bit.
The best range I got with my Ramsey AM transmitter was about a half city block. Much less than the 1/2 to 3/4 mile or more with the Rangemaster AM1000 I use now. Plus Ramsey transmitters work very hard to make 90 percent modulation. The transmitter kits can however produce some pretty respectable quality audio. Mine unit does. I use it as a back up transmitter.
Good luck. Sounds like you can easily fix this unit to do what it was designed to do. Check the audio final transistor and the RF output final transistor. They should be "hot" under normal operation. It is normal for these devices to run hot according to Ramsey. They run hot without failing. I hope you find this helpful.
Marshall Johnson, Sr.
Senior Pastor, President
Rhema Christian Fellowship, Inc.
Rhema Radio - The Word In Worship
AM 1660 - FM 93.5
http://www.rhemaradio.org
Hi Mark,
Be sure to put a loading coil between the rf out center pin in the RCA jack and copper pipe.
To determine how many turns must have your loading coil, visit to:
http://www7.brinkster.com/yvesroy/10ft-antenna.asp
Yves
i dont think the very loud moan on the recieveing radio
is caused because im only using a wire antenna.
There is either something very wrong with my power
supply or the circut, but im leaning toward the
circut, it was the first i'd ever soldered.
Ive been in touch w/ the people at ramsey and theyve
been very responsive and helpful. Thanks very much
for all the info! Im planning on getting at least a
sstran in a couple months but i bought the ramsey one
just to get my feet wet and play around with some
antenna designs. Ive muffed something w/ the circut
im afraid, but im not going to give up until it works...
The Ramsey AM1C is one of if not the most worst transmitters I have ever come across. Range is 1 to 2 meters at the most audio is not stereo because its AM and very hard to set the right frequency. Sure if you want to waste 40 buks or so go ahead.
NOT A GOOD TRANSMITTER FOR RADIO STATIONS
thats my experience see what others say too.
If this is going to be a problem. Why can't Ramsey come up with another AM transmitter design with a improved regulated filter on the circuit board so it can accept a walwart? I was going to buy this kit, but you're telling me that I need to spend an arm and a leg on a regulated/filtered power supply. I might as well just use AA batteries or a 9 volt battery. I don't want it to go far outside the neighborhood. I guess I will have to find a regulated/filtered addon circuit.
Is that the transmitter with no crystal? That's another issue, it will be difficult to keep it on frequency.
But the power supply problem also happened to me with the Ramsey AM25B Transmitter, which put out a high hum level with the supplied wallwart power supply.
I phoned technical support, and was very pleased with the treatment of the fellow who admitted that the problem was the power supply and advised getting a better regulated supply.
I put his advice to the test and found a transformer, added an inexpensive regulator circuit, and the transmitter became "serious and real", putting out a clean carrier.
The problem with building an inexpensive power supply is that it needs an enclosure, and the project gets larger and more complicated.
What became clear was that the Ramsey AM25B was an experimenters transmitter, and I would suppose so is the AM1.
Hi Mark:
The AM-1C isn't the greatest transmitter
in the world, but if you've never soldered
before, or put one of these kits together
before - there is nothing wrong with
starting there.
A great many people on this board have
been in electronics for decades. Everyone
in that category (including me) has built electonics
kits that have not worked. That's all part of the
experience. Many of us have built kits that have
NEVER WORKED - ever. But we learned from the
experience. Since the AM-1C is relatively
uncomplicated - you have a good shot to get it
going. I have had many Part 15 AM transmitters -
because I love this kind of experimentation. It took
me years to get some of them to work at all - or to
work well. Why? Because I had no good outside
information. Then I found this website 7 or so years
ago. And I finally got one of my transmitters to
work - with a loud signal that went about 1000 feet
from my house on a car radio. That transmitter was
a Ramsey AM-1 - which is just an earlier version of
your AM-1C.
A lot of us on this board experimented
with Part 15 transmitters decades ago. Some of
these transmitters were about this same as the
AM-1C as far as electronic theory was concerned.
But many of these transmitters used old fashioned
vacuum tubes and internal voltages that were in
the hundreds, instead of 12, for instance.
Some of these early 1950, 1960,
and 1970s kits were extremely dangerous.
But many of us loved communications
electronics and we (mostly unknowingly)
risked our lives to try to build and use
these old transmitters. I myself had a
small "explosion" which involved the frying
of electonics parts that fell mercy to
several hundred volts. The bright flash
frightened me a great deal. I was 14 years
old. But I loved what I was doing and pressed on.
(DON'T work with high voltage - it's not worth it.)
So see what you can do with that AM-1C. You
have to start somewhere.
I made some mods on my AM-1 and made it
a much better transmitter.
Some Part 15 experienters are satisfied with
a signal that will just stay in the house or yard.
(We call that housecasting or yardcasting.) And
that's a lot of fun all by itself.
Making a Part 15 transmitter go some distance is
not quick and easy. But it can be very very
rewarding. My Part 15 station had always been
for experimentation and learning about how it
all worked. But over the years, my station
(DOGRADIO) has had some listeners. They have
been people in my fairly close neighborhood
(within a thousand feet from my house depending
on how good the radio was) and some friends of
mine that would tune in with their car radios.
(While doing shopping or running errands in the
stores in my town - say - within 1/2 mile or
a mile from my house.) Some of my friends
have worked in broadcasting (as have I) and
they have been glad to drive around my town
and check reception of my station. West Hartford,
Connecticut is pretty large. My last successful
set-up covered the town center and a little bit
around it pretty well on a car radio. That was
maybe 1/8 of the town. Considering the fact
that I am almost legally blind and did not construct
the station very well, I am still happy with that
result.
For your AM-1C - your antenna turning coil has
to be very specific in "value" or it will not work.
There is plenty of info for this on the net.
The AM-1 has other problems that can be
worked on later. I modified mine for something
called "crystal control" - a term you may or
may not be familiar with. We can talk about
that later if you want. It helped a great deal.
But I was lucky - I had many of the parts.
So see what you can do if you want. It's
supposed to be fun. At least that's what I
think. It's fun for me. I really hope it will
be fun for you.
Bruce, DOGRADIO