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AM in 41.02MHz to 43.98MHz

AM was predominant until Armstrong came along with FM, even though EARLY experimental stations were more FM than AM as poor regulation on power supplies caused freq swings when modulated...there were no true FM rcvrs but the regenerative rcvrs of the days demoded both AM and FM equally bad 😂..the APEX stations were also HIFI at up to 20khz bandwidth...they got better range with AM vs FM since AM has no threshold like FM does and is considered a weak signal mode, unlike FM. Some US hams are now experimenting in the 40Mhz range under an Experimental license...some countries have actually allowed full blown licensed ham operation there..what's old is new again
 
I've always suspected that the reason the big broadcasters fought FM on the 40 mhz band was that 40mhz has incredible skip even better than AM at times. I remember hearing Tijuana Mexico police calls in Ohio frequently on 39.58 mhz back in the day.
 

Apex Radio Stations

History of ultra-high frequency Apex radio stations
www.theradiohistorian.org
^^^
One Apex station quoted its frequency response as being from 20 Hz to 17,000 Hz +/-1 dB, with a distortion from the microphone to transmitter output of 2.5%

^^^
While you would think that distance is what you want in a communication system, from the FCC’s point of view being able to limit a broadcaster to the immediate area was quite attractive.


I didn't know there was so much experimentation with AM broadcasting, previous to this info find, I thought that the only (early) AM "innovation" was the special reserved frequencies for "high fidelity" AM in the regular AM band.


(IMHO, in the 1920s/30s, some R&D money should have been spent developing a [simple as possible circuitry] all vacuum tube noise blanker [to be built in to most AM radios, probably not defeatable] - even after Armstrong demonstrated his implementation of FM broadcasting, AM radio remained the dominant radio system for several more decades)


Kirk Bayne
 
ContinuousWave said:
Some US hams are now experimenting in the 40Mhz range under an Experimental license...some countries have actually allowed full blown licensed ham operation there..what's old is new again
Click to expand...
What is now called the "8 meter band" is the 40.66-40.70 MHz ISM band. Normally it's legal for Part 15 use, but at a field strength of only 1000 uV/m at 3 meters. That's roughly 0.2 uW into a 50 ohm antenna.

A ham in the Atlanta area has an experimental license for a maximum of 400 watts ERP for this band, under the call WL2XUP. They're running WSPR with 20 watts out, and FT8 with 100 watts out. No CW or SSB operation that I'm aware of. The license took effect on 17 June 2021 and expires on 1 July 2023.

Some European countries have ham allocations on 8 meters, but I'm not holding my breath waiting for the FCC to allow it. If they do, I hope it's quite a bit wider than that tiny ISM segment.
 
As I recall, the original FM band allocation was in the 40 mHz range. RCA persuaded the FCC to move it to wipe out Armstrongs stations in New England. Years ago I had an RCA "Iron Fireman" transmitter. The first stage in the transmitter was a doubler that converted the exciter to the current FM band. That stage had been bypassed and a modern exciter drove the IPA.
 
Radio Bob said:
I've always suspected that the reason the big broadcasters fought FM on the 40 mhz band was that 40mhz has incredible skip even better than AM at times. I remember hearing Tijuana Mexico police calls in Ohio frequently on 39.58 mhz back in the day.
Click to expand...
VHF low band experiences e-skip as well as sunspot activity, unlike the medium wave frequencies which depends on the nightly ionization of the upper atmosphere.
Lately the 10 m ham band has been wide open. The current solar cycle has been more active than originally predicted. This could prove interesting in the next couple of years for DXers on low band VHF as well as the FM band.
 
Little did RCA foresee that moving "FM" to 88~108 would help its development.
40 MHz antennas vs 88 MHz antenna size for one meant a reasonable space on a tower is needed now.
And like mentioned, a lot less skip. Used to hear BBC Ch1 audio occasionally in Boise (F-layer skip).
 
While FM spectrum in the US is 88-108 mHz, it is 76-90 in Japan, 76-108 in Brazil, 65.9-74 in some eastern Europe countries, and
54-88 in US analog TV channels 2-6. My SW/FM portable radio's FM band is continuos 76-108 (to accommodate Japan).

Some time ago, I proposed extending the FM band downward for AM stations that wanted to switch over - like the AM expansion to 1700 kHz a few years ago. was there any progress made in that direction?
 
trusty said:
Some time ago, I proposed extending the FM band downward for AM stations that wanted to switch over - like the AM expansion to 1700 kHz a few years ago. was there any progress made in that direction?
Click to expand...
No receivers = no listeners.
No listeners = no market.
No market = no need.
No need = FCC won't do it.
And they've said many times that they won't.
 
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