The audio on the Yaesu floats. If you provide a true ground you'll get
AC hum. The transformer provides some isolation. I have an interface
circuit that will provide
you a better method to match the inputs and it's simple to construct.
I'll email you direct with the attachement of the circuit diagram.
Good luck,
dave
wa3gin
Rob K6RB wrote:
>Had the same problem with two FT-1000Ds and a DX Doubler. For some reason -
>never did figure it out - when the two radios are connected to the Doubler,
>there is an inordinate amount of hum in the Heil Pro Set phones. I tried
>tracing the wires, thinking there might be a misplaced ground in the Doubler
>cables, but found nothing. Even with the Doubler off, and the power removed,
>the hum was there. I finally eliminated most of it by buying 1:1 audio
>transformers at Radio Shack, and isolating the audio lines from the D's to
>the Doubler. There is some attenuation of the audio as a result, but the hum
>is now gone for all practical purposes. It is evidently an issue with the
>Yaesu, because I used the Doubler with a D and an IC-751A, and the Icom's
>audio was hum free! Hope that helps.
>
>Rob K6RB
>
>
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>http://lists.contesting.com/mailman/listinfo/yaesu
>
>
>
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