Thanks for all the replies on and off the reflector. My antenna, now a 90' top loaded vertical with 60 x 100' radials, was not transmitting well. While trying to fix it, I changed from an inverted L to the top loaded configuration, and I stripped off the hairpin coil (1/4" copper tubing) and the choke. The antenna is working better, but it's likely due to the new top loaded configuration rather than the hairpin/choke. With the antenna tuned without the hairpin, I thought it would be easier to put on an UNUN rather than retuning the antenna and putting the hairpin back on, which will lower the frequency.
73, and I hope to CU in the 160 CW contest in 2 weeks. Kenny K2KW On Mon, Jan 17, 2022 at 3:18 PM Mike Furrey <mikefur...@att.net> wrote: > Perhaps a "hair pin" match? I used a hair pin coil at the base of a > vertical that was 35 ohms. > > 73, Mike WA5POK > > > On Monday, January 17, 2022, 01:36:12 PM EST, Tim Duffy <k...@k3lr.com> > wrote: > > > I match my 26 ohm feed point with a simple L network. One series coil then > a > shunt capacitor. Steps up to 50 ohms perfectly. > > 73 > Tim K3LR > > -----Original Message----- > From: Topband [mailto:topband-bounces+k3lr=k3lr....@contesting.com] On > Behalf Of Richard (Rick) Karlquist > Sent: Monday, January 17, 2022 1:10 PM > To: Kenny Silverman; TopBand List > Subject: Re: Topband: 1:2 UNUN > > Maybe this will help: > > I use a 1:2.25 Unun (3 to 2 turns ratio). It will match 22.2 ohms > to 50 ohms. It is wound on a single 2.4 inch diameter core of 77 > material. A pair of RG-58 coax cables are wound around it in > tandem. I put on as many turns as would fit ... about 10 turns. > The shields of the two coax cables are wired in parallel. > > This results in essentially a trifilar winding (1. The shields; > 2. One of the center conductors 3. The other center conductor) > This trifilar winding can then be connected in the usual way to > get a 3 to 2 turns ratio autotransformer). The order of the > connections is: center conductor #1, then the shields, then > the #2 center conductor, in series. The radio drives > the 3 windings in series, and the antenna is tapped down to > utilize only 2 of them. I run this at 1,500 watts in > contests with no problems at all. > > The concept is extensible to a quadfilar winding constructed > from 3 coax cables in tandem (shields in parallel). This can > be wired with a 4 to 3 turns ratio resulting in a 1:1.77 UNUN. > This matches 28.125 ohms to 50 ohms. An alternate modality > I have used is to use two coax cables as in the 1:2.25 UNUN, > but make one of the coax cables from tri-ax. > > I can highly recommend UNUN's for the convenience factor if > your drive impedance is compatible with the available ratios. > They are broadband, no tuning. > > 73 > Rick N6RK > > On 1/17/2022 6:18 AM, Kenny Silverman wrote: > > Does anyone have a drawing on how to wind a 1500w 1:2 UNUN? And what > type > of core is needed? > > > > This is for my 160m vertical which is about 28 ohms. > > > > Regards , Kenny K2KW > > _________________ > > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
