Unique broadcast from WA2XMN on 42.8 MHz on the 19th of June 2025

While we are all familiar with the 88 to 108 MHz FM broadcast band today, its origins can be traced back to 1936 with the very first experimental station WA2XMN at Alpine, New Jersey. Experimental FM transmissions began from this location with a 40kW power level in the 42 to 44 MHz band and I have covered this in a previous post HERE.

On the 19th of June 2025 at 12 noon EST (16:00 UTC), there will be a unique broadcast from a WA2XMN on 42.8 MHz. This is usually done once every decade so it may be another 10 years before there's another one.

See post broadcast updates at the bottom of the post.

The organisers write... "Transmissions are in wide-band frequency modulation using the same technical standards as modern FM broadcast stations.  So, for optimum reception, you'd want an FM receiver with an IF bandwidth of about 200 KHz.  

This is a good time for collectors to wake up their "old band" FM radios.   However, narrower receivers will be able to hear the signal.  Scanners, military VHF sets (PRC-77 etc.), and the various modern wide-coverage receivers are generally up to the task.  Select "FM" and the widest selectivity available.  

An improvised antenna such as a "twin-lead" folded dipole should do the trick.  The transmitting antenna is vertically polarized, so orient your antenna the same way."

Coverage area... The map above shows the 'local' coverage area out to about 100 miles or 160kms. Anyone using say a SDR receiver with a vertical antenna for a vertical antenna for say 28 MHz or 50 MHz should have a reasonable chance of hearing it.

Considering that it's mid-June then there is also the possibility of some Sporadic-E which may allow reception over a much wider area. 

The map above shows the donut like coverage ring in which reception might be possible if there is an opening.

There is also a chance of multi-hop Sporadic-E to say the west coast of the USA or to Europe but this is highly unlikely for just a one off transmission.

More information about this one off broadcast can be found in this Radioworld article.

Post Broadcast Update: It would seem as if it was a bit late coming on air, maybe by 30 minutes or so.

From the organisers... "250 Watts via Ringo Ranger Antenna on the top crossarm of the Alpine Tower. Should continue until 5 PM."

Audio clip from the 19th of June 2025 transmission from someone living 12 miles away from the  Armstrong Tower using a Retekess TR105 radio....

Long video about Armstrong FM at Alpine...

Links...

1) WA2XMN website with reception reports
2) Email archive about test transmissions

The Experimental Station WA2XMN on 42.8 MHz

In 1933, frequency modulation or FM radio was invented by Edwin H. Armstrong in the USA to reduce the static and interference associated with AM transmissions.

In June of 1936, Armstrong established the experimental station WA2XMN at Alpine, New Jersey and began experimental FM transmissions with a 40kW power level in the 42 to 44 MHz band.

After the second world war, the FCC moved the FM band up to 88 to 108 MHz and this is the one we are familiar with today.

To commemorates the pioneering broadcasts of the world's first FM radio station, WA2XMN occasionally broadcasts on a frequency of 42.8 MHz. This was one of the frequencies used by Armstrong's station on the original FM broadcast band.

The station broadcasts with a power of 250 watts from the same Armstrong Tower in Alpine, New Jersey. When it does broadcast, the FM signals have been heard by radio enthusiasts within a 160km / 100 radius.

The QSL card at the top of the post was sent out for a transmission in April of 2018.

I'm not sure when the last broadcast was but it would be interesting to hear of any future transmissions.

Links...
1) WA2XMN website with reception reports
2) Email archive about test transmissions