Hi Ray - BC-611/Parachute mobile has been attempted fairly recently.  Mark AF6IM and friends do parachute mobile during the Pacificon event out this way, most years.  I have worked them on 2 meters FM and also 20 meters USB while he was descending airborne from 14K feet.  20 mile path obviously no problem.
He did try a BC-611 several years ago but apparently No Joy.  I was using a GRC-9 from Mt Diablo which would have been an optical LOS path but I did not hear him over that 15 mile path.  I recall he reported hearing me.  
A guy in Menlo Park (?) says he heard him but I am very surprised that he did over that 45 mile path, but I did not...  But it was cool to try - I was surprised that I could not hear him at my end..Even with the extremely poor radiation efficiency of that set.

Tactical combat use of a BC-611 while descending?  I doubt it was even tried (for what purpose? - especially for presumably low altitude jumping..)  Who knows, but an interesting thought experiment.
Tim
N6CC


On Sat, Oct 5, 2024 at 12:02 PM Ray Fantini via MRCA <mrca@mailman.qth.net> wrote:
Question for smart people, you would think I know this but as my wife will often remind me that I am not the sharpest tool in the shed. I think a half wavelength at 3885 is a hundred twenty feet or so, assume the 611 has a huge coil to make up for this short antenna? Mr. Smith once told me that although you can electrically shorten the active side of a antenna with a coil that dose nothing for your other side of the antenna, the counterpoise and for that to be most effective it’s got to be some sort of fraction of a wavelength. Dam, the counterpoise of the BC-611 is like one foot of case! Maybe there is some component of grounding thru your skin and boots or whatever but what if you’re wearing gloves? This is where the smart part comes in, I am assuming the efficiency of that short antenna and counterpoise results in an overall antenna efficiency of about lest then five percent! Certain some smart person out there can run the program and come back with an exact number.
Think about this in the context of parachuting, even if the antenna was fully extended the ground or counterpoise side of the antenna is like one foot if you were wearing gloves, I don’t think polarization or any of that stuff matters with that small antenna and radio.
My real question is how in the hell did you free fall , deploy the chute and all that other sky diving stuff and hold on to the radio in the first place? That’s an impressive feet.
Trivia! Two radios I have always like from WW2 are the DAV and its evil twin sister the MAB, don’t know if its true but I was told the MAB was designed and deployed as an air assault radio. It used a throat microphone and a weird skull cap that fit under a helmet with the radio strapping to your chest.
 
Ray F/KA3EKH
 

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