Hi, Wow, gorgeously constructed tuner by WZ5Q. I wish I had one. But is the center tap of the secondary really connected to the coax input ground as indicated in the schematic?
AB2TC - Knut Bill K9YEQ wrote > > Ron, > > Thank you for the references. I found the information very interesting to > say the least. Parts here would be an issue, but the construction and > methods to check and adjust the tuner were most valuable. Now just to > have > some drawer space! As Don had mentioned in an earlier post, getting the > balanced feed line to the shack can be quite a challenge, especially for > those of us who have rebar enforce concrete with no simple method to feed > through the wall. I think even the double coax systems to be a difficulty > especially when having to drill into the side of the house and miss all > the > surrounding materials, esp. the rebar. This may not be my last shack so I > have filed the project and will see what I can find for parts now before > this stuff gets extinct. That copper tubing is really becoming scarce and > I > am not even sure how much copper really is in the tubing and what impact > it has on the coils if not of the same purity. > > I did locate some surplus Comet vacuum capacitors in the $800+ range??!!! > > 73, > Bill > K9YEQ > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Ron D'Eau Claire > > > I have often had a voltage loop at the rig end of my open wire feed line > and > have never experienced a problem with stray RF, even though a neon bulb > lying near the ATU blinked as I sent CW. > > HOWEVER - I do use a homebrew link-coupled ATU with open wire line. It > lacks > the dual-differential tuning capacitors that Johnson used to adjust > virtual > coil taps for the feed line in the Matchbox, but mine has a much wider > matching range using actual taps on the coil. (The Johnson Matchbox is > only > rated to match balanced lines with impedances up to 1200 ohms). > > Link coupling has a number of advantages including a high order of > suppression of stray signals since there is no direct electrical > connection > between the antenna and the rig. Everything coming in (or going out) has > to > pass magnetically across the link coupling and through the tuned circuit. > That's especially handy if you live near a broadcast station. > > And of course, you can use the same tuner with unbalanced lines (e.g. > coax). > Just connect the shield to the center of the coil and tap the center > conductor out to either side. > > WZ5Q has a great example of a beautifully link coupled tuner at: > > http://www.wz5q.net/index/shack_data/tuna.htm > > It's bigger and neater than mine but the circuit is the same right down to > the RF current sensors. > > Ron AC7AC > <snip> > -- View this message in context: http://elecraft.365791.n2.nabble.com/open-wire-feeders-tp7140748p7141208.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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
