[NLRS] Left Field (or maybe even outside the ball park) thought on VHF Field Day modes

[Dr. Gerald N. Johnson]

Acoustical coupling will work, but poorly due to poor control of the 
modulation level, the emphasis/deemphasis (which also benefits male 
voices more than female), and noise in the place where the acoustical 
coupling is being done. A cough, snort, door bang, or operator 
explanation "IT WORKS!" will wipe out a call sign prolonging the contact.

Some radios have line level in and out for data in SSB and FM modes, The 
FT-857 for one so all it takes is the 6 pin mini din cable split out to 
a pair of stereo plugs for the sound card. I used a Yaesu CT-39A cable 
which is just a 6 pin mini din to bared wires. Surely there is a 6 pin 
mini din universal cable in the audio shops that can be cut in half and 
spliced to a male to male stereo cable cut in half. Same cable fits a 
TS-450 I think. The 857 has provision for VOX based on the transmit data 
tone to keep the connections really simple and it works well.

Otherwise speaker audio is a bit strong for a sound card so there needs 
to be attenuation and usually isolation (the transformer from a 1200 to 
56 kb modem card is good) to control ground loops. Sending needs both 
the transformer and attenuation when connecting to the microphone input. 
And many a rig then needs a PTT device based on some RS232 control pin 
or printer port. A microphone connection without the transformer usually 
ends up with lots of 60 cycle hum from ground loops. My lap top power 
supply puts lots of hash on the audio line, not from ground loop, but 
from switching.

73, Jerry, K0CQ

On 6/17/2013 4:22 PM, John (JK) Kalenowsky, K9JK wrote:
>
>
> To Jerry's comment and my apologies for not seeing it in what Doug
> initially posted.
>
> Sounds like I should have been more specific as to what I was suggesting
> as I AM aware of how the early AFSK over FM was done for RTTY but that
> was, as far as I know, with "wired" audio connections.
>
> Let's go with:
>
> ACOUSTICALLY COUPLED Audio Over FM, so ACAOFM.
>
> ;-) Should I try to apply for a Trade Mark on that, ACAOFM? ;-)
>
> 73, JK (and I DON'T mean "Just Kidding")
>