You're right, it will roll off on the high end, too, but the rolloff rate is usually much less steep especially if series-tuned. An analysis of my tuner shows that it would be only about 20 dB down at 30 MHz (when tuned on 40 meters) when parallel-tuned, and only about 10 dB down when series-tuned.
(A really versatile tuner allows you to switch the output capacitors between series and parallel. This allows it to match a very wide range of impedances, and I think you'd have to homebrew a tuner to be able to do this, unless one of the commercially made tuners can switch.) Al W6LX ________________________________ From: Al Gulseth <[email protected]> To: [email protected]; Al Lorona <[email protected]> Sent: Thursday, October 23, 2014 1:36 PM Subject: Re: [Elecraft] Interesting K3 QRM problem Pardon my ignorance here, but I thought a link coupled tuner would be more of a bandpass than a high-pass filter. CLC T-network tuners (MFJ etc.) are the ones usually associated with becoming high-pass networks if misadjusted. 73, Al On Thu October 23 2014 12:55:15 pm Al Lorona wrote: > This doesn't apply in Vic's case here, but his situation reminds me of yet > another benefit of using a link-coupled tuner with balanced line feeding a > horizontal antenna in the center. > > A balanced link-coupled tuner turns out to be a high-pass filter, so while > you're tuning it up on a ham band, it's rejecting stuff in the AM broadcast > band. > > When tuned on 80 meters, I've measured the 1400 kHz rejection of my tuner > at about 40 dB. Forty dB makes a 50 kW signal sound like a 5 W signal. I > might be in bad shape if I didn't have this tuner. > > Another good thing to remember when planning an antenna installation. > > Al W6LX > ______________________________________________________________ > 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 > Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
