This is my latest unit which incorporates a slightly larger type 43 ferrite bead. The main benefit is it has a larger 1/2 I. This allows more windings to be added to secondary, (longwire side). This allows for excellent tuning down to 40 meters.Comes wound with 1 turn primary and 6.5 turns on secondary.. With this ratio and a 61 ft sloper, I was able to get 1.2-1 SWR and 50 ohms. Remove 1 turn and it will achieve good tuning on 20, another turn tunes 15 and 10 (with slightly shorter antenna length). You will find that the impedance ratio will vary to optimize performance. A 63 ft sloper gave me the best low band performance. Shorter longwire will allow tuning on the higher bands, I have noticed that my small units allow better high band performance though, (10 and 6). Will fit inside back to back 1-1/4 PVC end caps with thin wall sleeve. (Not included) Note: I have added a picture of a 4:1 balun configuation.
The data sheet depicts balun winds but I hadn't shown one. I tested using my Buddipole configured as a off center fed dipole. It measured close to a perfect 1:1 match and 48 ohms.
Comparable to my Triple Ratio Balun but has much broader tuning. BNC connector available on request. (TRB-1B) Note: I have added another 4:1 winding configuration to allow use with a loop.These are proving to be quite versatile. Ith its larger size, should handle 200 watts into a good match. The item "Dual ferrite bead variable 91 unun for end fed longwire 41 balun OCFD or loop" is in sale since Tuesday, March 12, 2019. This item is in the category "Consumer Electronics\Radio Communication\Antennas\Ham, Amateur Radio Antennas". The seller is "eddieson" and is located in Bakersfield, California. This item can be shipped to North, South, or Latin America, all countries in Europe, all countries in continental Asia, Australia, South africa, New Zealand, Egypt, Reunion.