Indeed. Most of it is hand written, and come from Sinclair training material. These are copies, not originals and for the life of me I cannot remember where I got. I'm thinking it was given to me by one the Sinclair gurus in Aurora when I dropped in one day to pick up some invar rods for a Q202 duplexer that I was given. Anyway this guy came out of the shop and we had a short discussion about various Sinclair products. He took out to the plant floor and after went back to his office. He was a production manager and hand drew in front of me several curves for different filters. It turned into a 3 hour training session for me. He covered so much material that I retained only a fraction. He was very knowedgeable and extremely passionate about his work and the product. I ultimately walked away with 4 rods, gratis, and he followed up with a phone call a couple of weeks later to see if I was successful in refirbishing the duplexer. This was Feb of 1990 and the list price of the rods, then, were $18.50 ea.
lh On 5/18/10, N1BUG <p...@n1bug.com> wrote: > > That's correct. The folded dipole impedance is 300 ohms. The 1/4 > wavelength of 125 ohm coax transforms that down close to 50 ohms. > This 1/4 wavelength matching section is completely inside the dipole > itself. The transition to 50 ohm cable occurs somewhere near the top > of the folded dipole, so we see the 50 ohm cable exiting the dipole. > > In my dipoles the 125 ohm cable is RG-63B/U which, owing to its > partly air dielectric, no doubt has a higher velocity factor than > solid dielectric coax. So the section is somewhat longer than 13.5 > inches. I'm still trying to find a reference to the exact velocity > factor of RG-63B/U. > > It sounds like you have some very interesting (and rare) Sinclair > documentation there! > > Paul N1BUG > > > Larry Horlick wrote: > > > > > > On the drawing it does not show any 125 ohm cable, but I think what you > > are saying is that > > from the feedpoint of the folded dipole, inside the tubing there is a > > 1/4 wavelength piece of > > 125 ohm cable (about 13.5 inches at 2m) that is joined to 50 ohm cable. > > What we see exiting > > the tube (opposite the feedpoint) is the 50 ohm stuff. If this is > > correct it fully explains a drawing > > on the previous page showing a cross section of a single element folder > > dipole. \ > > > > lh > > > > On 5/18/10, *N1BUG* <p...@n1bug.com <mailto:p...@n1bug.com>> wrote: > > > > > > > > Thanks. That makes sense and should work out quite well for a > > harness external to the mast. Of course the quarter wave of 125 ohm > > coax will still be required inside each dipole, but the use of all > > 50 ohm coax beyond that point simplifies construction. > > > > Apparently Sinclair had different ways of doing it, perhaps > > depending on the exact model. Or maybe they changed the harness > > design at some point. > > > > Paul N1BUG > > > > Larry Horlick wrote: > > > > > > > > > I have a drawing from Sinclair that shows 4 stacked folded dipoles > > (it > > > does not indicate an > > > antenna model) using all 50 ohm cable. So using the 210C4 harness > > > picture from the link > > > below as a template, this is how it's done: > > > > > > Feedlines from dipole A, B, C, and D are any length, but > identical. A > > > and B go to a tee, > > > C and D go to another tee. The feedlines from the output (if I am > > > allowed to use that rather > > > crude term!) of these tees are any odd 1/4 wavelength (but do not > > have > > > to be the same) and go > > > to a 3rd tee. The output of this tee is 50 ohms. I suspect that > the > > > harness does not affect the > > > pattern, but rather it is the dipole to mast spacing. > > > > > > lh > > > > > > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > >
