Need to correct myself: I referred to the TS-950 when I meant the FT-950. Paul, W9AC
----- Original Message ----- From: "Paul Christensen" <[email protected]> To: <[email protected]> Sent: Wednesday, May 06, 2009 7:01 AM Subject: Re: [Elecraft] BHI HP-200 and other headphones >> I don't know about the big Icoms or their new 7600 and would be >> interested >> to hear from anybody who has one. > > The Icom '7700 and '7800 are nearly hiss-free at the minimum AF setting. > My > K3 is totally silent using Sony MDR-7506 and Bose Tri-Port headphones. > > There's generally only one time when I hear hiss from my K3 -- and that's > right after a F/W flash. I have now become accustomed to turning power > off > after the flash is complete, then wait > 5 seconds and re-start. If I do > not wait ~ 5 seconds, I oftentimes hear slight latent hiss. But it's > cured > 100% by this off-on sequence. > > The rig tried here with the highest latent AF hiss was the TS-950. In > fact, > the hiss level was so high that VS designed a special relay "cut off" > circuit to kill the hiss (and all audio) when the AF control is turned > full > CCW. > > On the TS-950, the hiss comes into play when the AF control is just > slightly > advanced. IOW, at full CCW, a relay opens up the headphone line. And > when > the AF control is advanced, the relay closes and the hiss becomes > apparent. > That's the first attempt I've seen by a manufacturer to mask a design > problem by using a relay as an audio 'knife switch." > > Anyone owning a TS-950 can try this test without wearing headphones: Turn > the AF control CCW and repeatedly advance and retard the control slightly. > Hear that relaying clicking inside the cabinet? That relay's sole purpose > is to mask hiss. > > Paul, W9AC > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
