Paul wrote: It could be an intermittant problem with the tuner or coax. But, let's hope not!!
-------------------------------- A good thing to do is to hook the tuner up to your dummy load and note the control settings. If things go sour again, put the dummy load back on and see if you get a match at the same settings. If you do and the antenna still won't load, you'll know the problem is in the antenna. Keep in mind that if you're using the internal balun in the tuner, it'll be out of the circuit when you hook up the dummy load! You could substitute a light bulb across the balanced feeder output for a "dummy load". It doesn't matter what you use as long as you can tune it up for a low SWR and note the readings. Then you'd have a reference to check back with if it happens again. If you use a light bulb, be sure to use the SAME bulb if you need to check things later. Also, I didn't think of it before but since you're using the internal balun, it could be heating on some bands. If the balun core gets hot enough and reaches a critical temperature (called the "Curie" temperature), its magnetic properties change dramatically. That would cause the SWR to jump sky-high all at once. This is not a "gradual" event. Although the core takes time to heat up, the properties of the core won't change significantly until the Curie temperature is reached, then it will suddenly change. After it's been allowed to cool down, the balun core will act normally again (unless it got so hot it fractured). The heating of the balun core would be a function of the current flowing through the windings, so it might act up only on one band and not others, or at a lower power on one band and only at much higher power on other bands, if at all. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
