I battled this for a while with my 706mkII. The problem is that
Vsend/Hsend are bidirectional. Depending on the keying circuit in your
external device, that device could look like a ground to the accessory jack
and key the radio. You need to add a protection diode or build a small
buffer keying circuit (which helps protect your accessory port also). A
couple of 2N3904's and a couple of resistors will do it. The circuit at
http://www.k6xx.com/radio/ic706amp.html solved my 706 keying issues.
>I set about making the cord. I am 100% sure that I have isolated and used
>the #3 HSEND pin. However, when I plug it into the transverter, it keys up
>immediately. I wasn't hitting the PTT button. I switched bands. I changed
>menu settings. I even turned the radio off and the thing is still keyed. I
>tried the same thing with the 144 amp with the same result. It appears that
>the pin is always grounded and therefore, any device attached to it is
>keyed.
>
73, Robert KR7O/YB2ARO, DM07ba/OI52ee (ex. N7STU)
kr7o@vhfdx.com
www.vhfdx.com (KR7O/YB2ARO homepages)
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