If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #1517
Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304
Hi everyone!
As a project for class I am building an AM radio transmitter from the AMC1 kit from Ramsey's Electronics.
I have finished soldering all the elements and have chosen a band to broadcast on but when I tune the transmitter with the adjustable inductor I get nothing but stating, then, a noise, starts low pitch then gets higher and higher and then goes lower and lower then nothing.
If I had to guess I'd say that my audio signal wasn't getting through the system... does this sound about right? Please help me trouble shoot!
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Here are some possible causes of your problem:
(a) the circuit is oscillating - perhaps due to poor layout of input parts being too close to output parts OR poor bypassing of supplies OR excessively long leads etc
(b) Some part of the audio circuit is acting as a rectifier (so-called 'direct detection') and is demodulating interfering signals from, for example, a nearby computer, or fluorescent light.
(c) The circuit is functioning to some extent, but that the local interference is very much stronger than the desired signal.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
coillah wrote ...
but when I tune the transmitter with the adjustable inductor I get nothing but stating, then, a noise, starts low pitch then gets higher and higher and then goes lower and lower then nothing.
On second thoughts, this sounds like either
(a) uncontrollable oscillation OR
(b) oscillation starts, but fails due to starvation as it tries to build. OR
(c) the frequency is wandering all over the place, so that no sooner do you tune it in on your receiver, than it drifts off somewhere else.
(c) All of these things!
Without sight of the circuit diagram, all is only a best guess.
Registered Member #1517
Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304
I do have it plugged into a wall. Could it be a simple grounding issue?
I will post the schematic when I get home. I was reading about the kit that is one level up from mine, it has a phase lock loop circuit in it that keeps the frequency from drifting, which is another problem that I believe my circuit is having.
But as for the noise, I went back through and made sure my leads were as short as they can be. I have a 6ft antenna, using a piece of twisted wire, I am going to try a solid copper antenna when I get home.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
watch out, you could get in serious doodoo with Ze Fuzz, seems that the FCC are clamping down on anyone purchasing RF electronics kits as well as the companies making and selling them.
Registered Member #1517
Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304
I am using a power adapter, this should filter 60hz line noise? I don't believe the actual power circuit for the radio is filtered.
I wonder, how does the FCC track down unregistered signals? Also, how much does a station usually cost? I checked around the FCC website but couldnt find a straight price.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Radio Transmitter Kit
