[Elecraft] KX3 Audio output

[Rich - K1HTV]

Jim, 
  I can see that magnetic fields in a vehicle could cause problems with a
microphone, as the output level is in the -50dBm range and is much more
susceptible to it . Using equipment like the KX3 at consumer line level (-20dBm)
there would much less of a problem with magnetic fields, so a less expensive,
unshielded in-line transformer would probably work just fine.

73,
Rich - K1HTV

= = =

-----Original Message-----
From: Jim Brown [mailto:jim at audiosystemsgroup.com] 
Sent: Wednesday, June 01, 2011 13:04 PM
To: Reflector Elecraft
Subject: Re: [Elecraft] KX3 Audio output

On 6/1/2011 5:31 AM, Rich - K1HTV wrote:
>   Looks like the addition of an inline audio transformer between the 
> wireless transmitter's miniplug and the KX3 (or any device powered by 
> the vehicle) would resolve the potential problem which you have addressed.

Yes -- IF the transformer did not pick up magnetic fields from the vehicle's
systems.  I saw that when doing testing of some pro mics for RFI in a Volvo S80
-- the output transformer in the mic was not shielded, and picked up trash.
That would be fixed with a transformer that has a mu-metal shield, but shielded
transformers are expensive.

73, Jim K9YC