You are right about the ATU. It was my mistake comparing the ATU-ON which had been tuned at other than 50 ohm load compared to the ATU-OFF.
As for PRE+ATT, I just measured MDS with the PRE and ATT settings either both on or both off. Having both PRE and ATT switched on gives 2 db poorer MDS than having both off. That is unnoticeable of course, just a point of interest since the specs would seem to indicate it should be a couple of db better. Does anyone use both PRE+ATT ON and find it noticeably better? I can't hear any difference myself. 73, Drew AF2Z On Wed, 11 Aug 2010 06:21:05 -0700 (PDT), AB2TC - Knut wrote: > >Why do you think you gain in MDS (presumably you mean a *lower* MDS) by >bypassing the ATU? If the ATU is needed for transmit, it will also be >benficial in receive. I don't have the K3 ATU, but both manual and automatic >tuners in my antenna system and can certainly certify that when switching in >the tuner when needed, the receive signal goes up (mismatch loses receive >signal too). > >AB2TC - Knut > > >drewko wrote: >> >> Actually, you will probably LOSE a couple of db by switching on both >> preamp and attenuator compared to having both switched off. (Measure >> your MDS and compare results if you don't believe...) >> >> Regarding weak signals, one factor that is overlooked is the ATU. By >> switching it to bypass you can gain 5 or 6 db in MDS. Of course, you >> would want to switch it back on when you transmit. >> >> I wonder if the ATU could be programmed to automatically be bypassed >> on receive? You would perhaps not want the ATU to be switched in and >> out at break-in speeds, but after a suitable semi-breakin delay. I >> think that would be a handy option for weak signal work for those of >> us who must use the ATU. >> >> 73, >> Drew >> AF2Z >> >> >> <snip >> ______________________________________________________________ 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
