100 milliwatts and more

This is a complete archive of the old MWA website that was established
in October of 1997 and was terminated in March of 2004. Please keep
in mind that some of the information here is now outdated.

Mail Order Sources Page

Updated August 6, 2003
Please report errors and dead
links to ____________

FCC-Certified Transmitters

web site: am1000rangemaster.com

Home of the RangeMaster AM1000 transmitter, formerly known as the Hamilton. High quality construction, high quality modulation, and good range. Price varies from about $600 to $800 depending on the options you select. I have seen many positive comments on the 'net from users of these units, and no complaints!

Information Station Specialists (ISS)
phone 616-772-2300

Home of the Infomax AM transmitter, an FCC-approved ready-to-use unit that plays a digital recording or allows you to broadcast live audio. The price is about $900.

TalkingSign.com Inc.
web site: www.talkingsign.com

This company sells ready-to-use Part 15 transmitters that can broadcast live audio or a digitally recorded message. The price is $495 plus shipping.

DiPonti Communications
web site: www.wblq.org/diponti.htm

Since 1996, DiPonti has been one of the few retail sellers of the super-high-quality transmitters made by Ultra Sensors Inc. These units are not cheap but they have good range and sound quality.

Wild Planet Toys

The Wild Planet Radio DJ is a toy studio and transmitter that broadcasts on 1610 kHz and has a range of 30 feet (maybe more if you optimize the antenna and use a sensitive receiver). You can order from amazon.com and a variety of online toy stores including these: source#1 | source#2 | source#3 | source#4 | source#5

For tech notes, performance enhancing tips and a look at the circuit board, follow this link.

Other Transmitters

Gizmo Transmitter

The Gizmo is a ready-to-use 100 milliwatt transmitter. It has stable PLL frequency control in 10 kHz steps from 500 to 1800 kHz. It also includes an LED that indicates when you have achieved a good balance of modulation level and antenna tuning. The Gizmo is small (less than 4x3x2 inches) and lightweight. You will have to provide a well filtered and regulated 12 volt power supply for it; cheap “wall wart” power adapters will add a hum or buzz to the signal.

Update: A new transmitter called the Metzo, featuring a built-in audio compressor, is available.

PCS Electronics  new listing

This company has introduced the AM MAX I transmitter, a 10-watt unit with many nice features. One version covers the longwave and mediumwave broadcast bands; another version operates on shortwave and might be of interest to ham radio operators who want to experiment with good old amplitude modulation.

Low Power Radio Broadcast Company
web site: www.ontheair3.com

Part 15 transmitters for around-the-house 'casting applications such as sending Old Time Radio tapes to your antique receivers.

Radio Systems
phone 856-467-8000
web site: www.radiosystems.com/Products/lowpower.html

Products include carrier current transmitters, AC line couplers, and accessories for campus AM radio stations; TIS (Travelers Information Station) transmitters; plus "low power AM transmitters and mini-studio packages to economically transmit news, sports and music throughout camps, schools, and other small institutions."

Also Noted:

In the US, Chris Cuff makes a 10 milliwatt AM stereo transmitter which is sometimes called the "Alfredo Lite." You can read a little bit about it at the bottom of this page.

If you're in the UK and you're looking for an around-the-house transmitter, check out this review of the AM-02 Modulator.

Transmitter Kits

SSTran  new listing
web site: www.sstran.com

After observing the poor quality of the other kits on the market, the operator of this company spent a couple of years intensely studying low-power AM transmitter design and created the AMT3000. Its features include PLL frequency synthesis, an audio compressor-limiter, and a tunable antenna matching circuit that efficiently matches the rig's output to short antennas without the need for additional loading coils.

web site: www.vectronics.com

Vectronics makes a variety of radio hobby kits, including a shortwave converter, crystal radio set, various ham radio transmitters and receivers, etc. Their VEC-1290K is a very low power AM transmitter kit costing about $30. This kit is so good compared to the others in its price range that we have made a whole page about it.

Ramsey Electronics
793 Canning Pkwy
Victor NY 14564
web site: ramseyelectronics.com

The Ramsey AM-1 transmitter kit is a 100 milliwatt AM transmitter. It is easy to build but it suffers from frequency drift and mediocre audio quality. Avoid buying the AM-1.

Ramsey also makes a more expensive AM kit with PLL tuning called the AM-25. Audio quality varies from mediocre to moderately good and might be influenced by your antenna design. (On AM, antenna bandwidth = audio bandwidth.) The "wall wart" power supply that comes with the kit is inferior and will add a hum or buzz to the audio, so it has to be replaced by a properly filtered and regulated 12-volt power supply. Some specimens suffer from overheating components and one message-poster on the CRUSA board claimed his AM-25 burst into flames. On the other hand, some people have posted messages elsewhere saying they're perfectly happy with their AM-25s.

Antique Electronic Supply
6221 South Maple Avenue
Tempe AZ 85283
phone 602-820-5411
web site: www.tubesandmore.com

This company carries 3000 different kinds of tubes, plus sockets, chokes, transformers, high voltage capacitors, and related parts. They have more than 100 books about tubes and "retro" radio equipment including picture books, reference data volumes, and construction project manuals.

AES sells a one-tube AM transmitter kit patterned after a 1939 Zenith circuit. It is fun and easy to build, and suitable for around-the-house broadcasting (e.g. feeding nostalgic programs to your collection of antique radios). However it is weak, a little drifty, and the carrier frequency jitters in response to the audio. If you've never built an electronic device but you have some experience with hand tools, this kit might be a good beginner's project for you. Just don't expect too much.

The circuit has been discussed several times in the newsgroup rec.antiques.radio+phono, where "CommQuart" wrote this about it: "Being a modulated oscillator it suffers from FMing, poor modulation depth, modulation linearity and audio bandwidth problems." Follow this link to see the schematic. Follow this link to see some very nice photos and a schematic of John Byrns' modified AES transmitter.

North Country Radio
PO Box 53
Wykagyl Stn.
New Rochelle, NY 10804-0053
phone 914-235-0053
web site: northcountryradio.com

North Country's AM88 transmitter kit has PLL frequency control, a built-in peak limiter, and claims to have good audio. It can be used in the 160-190 kHz experimental band and on the AM broadcast band in accordance with the FCC's Part 15 rules (or their equivalent in other countries).

Assembling this kit is difficult. Cramming 51 resistors, 48 capacitors, 4 IC's and two dozen other components onto a two-sided 4x4 inch board results in solder joints that are very close together. The set-up procedure requires you to test voltages at 12 different points on the circuit and fiddle with quite a few adjustments. This is not a kit for beginners.

Comments I've received about the AM88: Stephen P of RFA calls it "over-engineered and hard to build." Bias Comms wrote, "A fairly elaborate circuit for what they're trying to achieve... it seems a longhand way of generating a very few milliwatts of RF..." Another informant told me "It sounds okay for an AM rig. It's stable and puts out a clean signal."


If you need frequency-control crystals, here is a list of sources you can peruse: AF4K

Some experimenters on the 'net speak highly of PR Crystals, 2735 Avenue A, Council Bluffs, IA 51501, telephone 712-323-7539.

On the CommunityRadioUSA Board, ryan recommends contacting [email protected]



DC Electronics
PO Box 3203
Scottsdale, AZ 85271
web site: www.dckits.com

Transistors, integrated circuits, printed circuit board materials and prototyping boards, connectors and enclosures. Kits for power supplies, PLL oscillators, FM transmitters, and other projects.

MFJ Enterprises
Box 494
Miss. State, MS 39762
web site: mfjenterprises.com

Antenna tuners, SWR/wattmeters, low pass filters, dummy loads, receiver kits, books, and more. Free catalog.

Panaxis Productions
PO Box 130
Paradise, CA 95967
phone 530-534-0417
web site: www.panaxis.com

A source of circuit plans and informative booklets for mediumwave and other radio experimenters. In business since 1975. Plans include a couple of AM broadcast transmitters and a broadband 5-watt amplifier for the band. Booklets contain data on carrier current operations, cable FM, LPAM antennas and other topics.


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