Originally Posted by
Squawk7700
So back then before the interweb and television, did everyone have a HF sitting at home, is that what they are trying to lead us to believe?
Originally Posted by
CONSO
Well in the 40's- I had a crystal radio that at night could pick up an AM radio station KSL salt lake from the san franciso area . ... so obviously one could pick up a high freq bounce form 4 times that distance .....
Not so sure that's a good comparison. SFO to SLC is about 600 miles, the distance from Gardner Island to points in the continental U.S. is more like 6000 miles.
Also, Earhart and Noonan had a nominal 50 watt HF transmitter with a relatively simple antenna. KSL upgraded their transmitter to 50,000 watts in 1932 with a ten-acre grounding array. See the lower righthand corner of page 9 in this issue of Broadcasting magazine:
https://www.americanradiohistory.com...2-11-01-BC.pdf
Harmonics in early aircraft transmitters were presumably not suppressed as well as they are today but I would guess that the first harmonic of the 6210 kHz signal would probably have less than five watts of radiated power at 12420 kHz. It seems very unlikely to me that these weaker harmonics would be received by housewives and children on 'family radios' back in the States. The TIGHAR paper cited above assigns small probabilities of reception to many of the civilian reception reports but in several cases then rates them as credible or credible beyond a reasonable doubt.
By the late 1930's the superheterodyne receiver was indeed commonplace in American homes with many having shortwave reception on frequencies above the AM broadcast band. As you know, your 1940's crystal set had no RF or audio amplification so you did need that really good clear channel signal from KSL to power the high impedance headphones for listening.