The AM Forum

This is my homebrew link coupled tuner now with a "swinging" link to eliminate loss and to provide a broader complex impeadance conjugate match without having to tap the input link coil. Notice the size difference with my old coil. If you look closely, you can see where my old coil had caught fire. This new larger coil is out of a Raytheon RA-1000 AM broadcast transmitter. The swinging link coil inside the larger coil measures 4" diameter! The larger main coil measures 6.5" diameter. Changing this coil did two things for me, eliminated the lossy small link on my smaller coil that warmed up on TX, and with the added inductance I can now shorten my antenna 60 feet on the side that folds back on itself. By doing this, the effective radiation will improve 2.58db as per EZNEC.

More pics...

I wish you would have cleaned that thing.. LOL

Sounded real nice on 40 today.. 40 to 50 DB over..   


Clark

Those are sure some good looking components.  And what's left in the bc rig are nothing to sneeze at either.  I think I see a couple of 833s plus the iron on the bottom. 

73

Rob
K5UJ

get some coil clips from B & W. much better than gator clips for yer coil. Surface area, man, surface area.


http://www.bwantennas.com/coils/coilclip.htm

but will that tuna STRAP ;D

LOL.. Those wont work. That is a huge flat Coil.  Not round.

C

Huge Edge wound, very nice. I like the vario-coupler method of changing the link coupling. I never thought of that approach for a tuner, one of those oh yea moments when I saw the picture.

Too bad those coil-clips are so small... I like the screw it down tight feature.

I don't have any coils that use less than #6 wire..

Mostly #4 and 1/4" tubing.

I just use a large gator clip and form the tips with pliers.



That is a purdy swingin link coil... even if it does have several years worth of "natural" insulation built up.   ;)

That is the same coil I use in my 160 tuner. It works great--I jumpered a few turns on the input link--maybe I should have left it alone. I used the reactor & mod trans in my xmtr. That reactor is one nice piece of iron.
Skip

they work, but you put the ribbon behind the screw, not in front. tighten that screw down, and you cant move it. harder to adjust  but the contact is solid.

if that ribbon is real wide, then yup, it wont work. I've done it on edgewound coils. all depends how wide the ribbon is. I cant get a good perspective from the pix.

Nice tuner.

I used the clips that came with the RA1000 coil. Worked FB.

How about once you figure out where the taps belong, you solder short straps for each tap to the coil, then put banana jacks on the ends of each tap strap, making these only an inch or less long.   one strap with a banana plug to the rest of the circuit.  change taps by moving the banana plug from one jack to another. 

73

Rob
K5UJ