Hi John: Love the story John --- an inquiring mind is a treasure. Kindest regards Jim K9AXN
----- Original Message ----- From: "John Coleman" <[email protected]> To: "Discussion of AM Radio in the Amateur Service" <[email protected]> Sent: Monday, August 17, 2009 8:52 AM Subject: Re: [AMRadio] Classic Link Coupled Tuner > Hi Brian: > Next time we come up there I will be sure to give you some notice. But I > had already taken a side trip to Don's, K4KYV, to get rid of some stuff. > I was needing to spend some time with the kids there in Searcy. > If you are getting a good match and there is no heating then the energy > from the XMTR must be getting to the antenna. I would worry too much > about it all. But it sounds like you have the same brain disease that I > have, CAN'T STAND TO NOT KNOW WHY. I must have spent weeks studying and > experimenting with this matching stuff and neutralizing circuits, don't > even get me started. HIHI One thing I have found is that the breadboard > design is the best for changing and learning and the shot glass can be > used for an insulator or to ease the frustration, which comes often for > me. > While on the subject, I must tell you of an experiment I did some time > back (25 years ago). I put a 6AL5 tube in the top box of a Heath Cantenna > and lit it up with a 6V lantern battery. Using only one diode, I > connected the plate directly to the dummy load and the cathode was by > passed to ground with a .01uf ceramic capacitor and then connected to the > little RCA jack on the top box. Now I had a decent peak reading RF > detector. I just measure the DC on the RCA jack to indicated the peak of > the RF voltage (very accurate by the way, but that's another story). I > took 60 ft of open wire balanced line made of #12 wire with Phenolic > spacers about every foot and stretched it out across the back yard > suspended by wood chairs and such. The dummy load RF detector was then > attached to the far end. I had the balanced antenna tuner connected to > the feed end and a SWR meter between the tuner and the XMTR. I adjusted > the tuner so that running 800 watts and with the SWR meter sensit > ivity all the way up it showed nothing on the reflective meter. I then > took my Simpson meter out to the dummy load and measured the voltage at > the output of the 6AL5 RF detector. I of course don't remember the exact > voltage but let's say about 250V DC. Then I connected 100 Ft of RG8 to > the dummy load and the other end to the SWR meter. The SWR meter still > show flat but the RF detector meter showed less voltage, not much less but > something like 240V. I thought maybe I have made a slipup somewhere so I > when through all the procedures again making sure that I disconnected the > battery from the 6AL5 when not measuring so as not to have the filament > voltage going down in between measuring. I got the same results each > time. So I was finally convinced that the losses in a good tuner are > negligible and the looses of coax far exceed the losses of open wire line. > > John, WA5BXO > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
