Welcome to Hobby Broadcaster.co

NOTE: This website is in NO WAY connected to: hobbybroadcaster.net, hobbybroadcaster.org, hobbybroadcaster.com, hobbybroadcaster.us
or any other site or page within a site that contains "hobbybroadcaster".  This is a completely independent site.

Hobby Broadcaster.co is dedicated first and foremost to scientific and un-biased lab testing of Part 15 radio broadcasting equipment. All equipment tested is obtained through regular retail sources eliminating the opportunity to receive and test a "hand picked" unit through the manufacturer or distributor.  Always, the actual numbers and test results will be reported. I have no connections with any manufacturer and do not have to worry about upsetting friends, companies or distributors that provide equipment for testing. This website contains no advertising and never will.

Clearly web design is not my forte'. This web site will be mostly text with occasional graphs and photos in the test reports. I don't have the time, desire or skills to try to build an impressive website to amaze friends and colleagues.  The purpose is strictly to provide informational, unbiased, accurate test results of equipment.

Part 15 FM Transmitter Tests

NEW EDM Accessory Antenna Review

EDM-LCD-CS Transmitter Review

My original group of FM transmitter tests completed in the fall of 2015. Includes:

C. Crane  FM Transmitter 2
Whole House 3.0
Decade CM-10
General Electric EWT-950

Tests for all these transmitters are in one pdf at the link below:

One short addendum to the Whole House 3.0 part of the above tests. "Update: October 2016, I tested five brand new Whole House 3.0 units back to back, all within a minute or two of each other, under identical conditions.  Of the 5, field strength at 3 meters ranged from a low of 5635 uV/m to a high of 7585 uV/m.  Remember, legal is 250 uV/m."

C. Crane FM Transmitter 2 Test #2 Back to Back Test of Ten Transmitters:

Fail-Safe RangeMaster X-Tream Transmitter FSX-05B

Broadcastvision AXS-FMTXD

For those interested, my qualifications:  43 years commercial broadcast experience including chief engineer for 3 - 100,000 watt FM stations and 2 directional AM stations.  Have built numerous studios from the ground up, including AM, FM, production, and music recording facilities.  B.S. Degree Electronics Engineering, Holder of FCC General Radiotelephone Operator License often referred to as the "GROL".  Once known as the First Class License, or "First Phone" license. Member of and certified by the Society of Broadcast Engineers. General Class Ham radio license. Earned my first "Ham" license when I was 11 years old. Have been operating my own Part 15 AM station since 2013.

General FM transmitter test parameters: All tests of FM Part 15 transmitters were done with transmitters purchased through regular retail outlets. The same way in which the typical consumer would obtain a transmitter.  It is my strong belief that if you ask a manufacturer or distributor for a transmitter for testing they will make sure you get one that is likely to be legal, when those sold to the masses may not be. Every transmitter in the tests above claimed to be certified by the FCC.  All except the C. Crane FM Transmitter 2 proved to be over the legal limit, generally by a rather dramatic amount.  They clearly didn't pass certification with the same transmitters they're sending out to customers.  It's a rather simple matter to modify a transmitter to decrease it's output and allow one to pass certification. I have no evidence that this happens other than the fact that transmitters are getting certified that clearly do NOT pass the certification tests, including requirements for things other than field strength (see the Fail Safe review for an example). There are also transmitters available with a certification number that does not correspond to the device to which they are attached. All tests are done in a wide open test field where the nearest objects are at least 1/4 mile away to remove the chance of any reflected signal altering the readings. And at 1/4 mile there are just a few trees. No buildings, nothing metallic. Although a legal FM Part 15 transmitter would not have enough field strength to reach a reflector even a few hundred feet away much less have enough power to reflect and make the trip back to the test meter.  They are 7 feet above ground as this is the heigh required to determind the correct antenna factor used to calculate actual field intensity. The tests are done with the transmit and receive antennas horizontally polarized and 7 feet above ground and exactly 3 meters apart. The transmitter is supported by a wood 1x2 piece of lumber to insure there is no metal near the transmitter. You will note in various tests that proximity to metal objects can have a dramatic effect on readings. In most of the tests the readings are taken with no more than power applied to the transmitter either through internal batteries or through external power when that is the only option. In addition in most cases readings are also done with an audio cable connected, since this is how it would be used when in operation. Most transmitters show a substantial increase in field strength once an audio cable is connected. Also changing the angle of the power cord can also change the field strength.  Readings are always done with a Potomac FIM-71 field strength meter, a standard of broadcast engineers for decades and a unit used by the FCC and also listed in actual FCC reports of stations that were cited for violations.  When available (e.g. I bothered to bring it along) readings are verified with a Z-Technology R-506 field strength meter. This is also a device used by and mentioned in many FCC documents for transmitter violations. I have yet to discover any discrepancy between tests with the FIM-71 and R-506 so may occasionally not double up on the tests. All these are used in my regular work as a broadcast chief engineer they are calibrated regularly and certified to be accurate.  They are used with their matching manufaturer provided calibrated dipole antennas that are adjusted in length for the frequency being used for the test. Appropriate antenna factor is applied to determine field intensity based on data provided by Potomac or Z-tech.  Remember the legal limit for a Part 15 transmmitter is 250 uV/m measured at 3 meters. Additional parameters or conditions for tests are mentioned in the test reports.  Below you'll find a list of equipment used for testing with links to the manufacturers web sites in case you'd like to learn about the instruments used.  In the shop, the transmitters are tested for actual RF output (e.g. watts, or milliwatts output) and modulation (do they modulate 100%? How accurate is any modulation indicator on the transmitter, etc).  They are also tested on a spectrum analyzer for harmonics and other spurious emissions.

I always have transmitters waiting to be tested, and if you have a suggestion for one to be tested let me know at ironrangecountry@mail.com. I prefer to test currently available certified transmitters, although I will also test a non-certified transmitter occasionally.

Equipment Used For Testing

As the results of my testing has generated more interest I've gathered the links to all the of the various tests.  New tests will be added when they are complete.  Note that I will rarely do any testing November through April, as my test field will be under several feet of snow!  My test equipment is used in my engineering work in commercial broadcast radio so it is all maintained and calibrated regularly.

Requests/suggestions for transmitters to be tested may be sent to: ironrangecountry@mail.com.  I make no promises that I will test all requested devices.  Old or generally unobtainable models are of less interest.  Also I prefer to test units that are FCC Certified (or at least claim to be).  All devices tested are always purchased through regular retail outlets with no involvement or knowledge of the manufacturers.

For those technically inclined the equipment used for testing includes (but is not limited to)

Potomac FIM-71 field strengh meter with it's calibrated ANT-71 antenna

Z-Technology R-506 field strength meter with it's calibrated antenna

(both the above devices are commonly used in the field by the FCC)

Inovonics 531N Modulation Monitor

Inovonics 525 AM Modulation Monitor

Coaxial Dynamics Watt Meter with CD Custom manufactured 100 mw and 1 watt FM band "slugs"

Rigol DSA 815 TG Spectrum Analyzer

Tektronics Oscilloscope

MFJ 259B Antenna Analyzer

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