On Friday 14 February 2025 09:40:38 am wn4isx via groups.io wrote:
Is there a local ham you can talk to via telephone while he monitors your audio?
As to coupling a PC to a transceiver, yes it can be done, transformers are good for breaking ground loops but bad for picking up stray magnetic shields.
These show several ways to do it.
The first thing I thought of when I saw "mic input" was the possibility of overdriving it, but both of those links address this issue.
Mr. Browne knows hit stuff, both RF and AF. He was a respected audio expert for ~40 years before retirement.
I use transformers but they are obscenely expensive units with integral faraday cage, electrostatic shield between primary and secondary.
Jensen makes similar transformers (prepare to rob a bank). I salvaged the transformers from an audio distribution amp designed back when we (professionals) used 600 ohms for everything audio, then we went with 10K loads and the old distribution systems were tossed.
I'm not sure I see the need for something that fancy...
Rod Elliot shows two circuits that can modified to drive a transceiver,
one for transmitting one for receiving
The PC to PA can be modified for PC AF out? to transceiver AF in
The PA to PC can be modified for transceiver AF out to PC AF line in.
If you are lucky, in a location or ham shack with no stray electromagnetic fields, Mr. Elliot's designs should work fine.
Funny that he mentions phone transformers. Some time back I scrapped out a bunch of modems, some PCI bus but most way older than that, most "winmodems", unusable for me as I don't run windoze. There was a transformer on each of these, and assorted other useful bits. It's interesting that he shows different dc resistance for primary and secondary, I'd have thought that they'd both be the same.
Some years ago a friend of mine (who was a sound engineer) pointed some small transformers out to me in the Mouser catalog. They were fairly cheap as I recall. He said that they worked quite well if you had a resistor across each winding, otherwise they tended to ring with higher signal levels.
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Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
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