I didn't have a series capacitor on the last tuner and was able to get 2:1swr no problem just adjusting taps and tuning tank capacitor. With the 5" coil it may be a little harder and it would probably be easier to get a perfect match with a series capacitor but I'd rather use a swinging link unless there less efficiency. Also I noticed most just move link in and out of the coil but I've seen some that rotate the primary coil inside of the secondary, does this do the same thing?
Moving the link in and out of the coil does the same thing as rotating the link. With the variable link, you wouldn't need the series capacitor IF you can get a perfect match with the link partially in (or out of) the coil. If you cannot get a match using the link without a series capacitor, try varying the number of turns of the link (use a temporary experimental set-up) until you find the magic number of turns with the link about two thirds inserted or rotated towards maximum from minimum. Then make up a permanent variable link with that number of turns.
I have always considered a variable link AND series capacitor redundant, an unnecessary complication. I have used the series capacitor only when the coil had a fixed link.
One more question. I got some 1.2 volt bulbs from radio shack that I was using in the ladder line (jumped across about 1.5 to 2 feet of ladder line). Is this an ok way of checking balance? I did run dc through them before installing to make sure they show the same brilliance with the same current to make sure they were "matched" and they were the same. They are also fun to watch while I modulate
It works. Even more sensitive are the miniature Xmas tree lamps that run off very low current at very low voltage, designed to run in a series string off 110v line voltage. In any case, adjust the length of the jumper across the line till the lamps give a dull orange glow. If you run them at full brilliance, they are less sensitive to small variations. With the advent of LED xmas tree lights, the incandescent lamps may be getting harder to find.
Another precaution, whether using lamps or an rf ammeter: measuring balance at only one point in the line may give a false indication of balance, since the standing waves on the two conductors of the OWL may not be exactly the same. If possible, insert the current indicator at a second point along the line, about 1/8λ away, and compare readings. If the line still shows good balance, you can be sure that it really is balanced.
If it shows some unbalance, it isn't the end of the world. If the transmitter can still be loaded up to full power, some unbalance isn't going to hurt anything much, although you may not be getting 100% of the rf into the antenna and the feed line may be radiating a little.
For best balance in the feed line, DO NOT ground any part of the main coil or split stator capacitor in a balanced link coupled tuner, such as the midtap of the coil or the frame of the split capacitor. Let the coil and capacitor float free, and make sure the link floats free from the main coil.
