[NLRS] 70-cm Antenna Dilemma

[aduhawk at comcast.net]

Carl -- Your antenna is a KLM of a long ago vintage.  The driven elements (yes, that's right, elements) have the zig-zag aluminum strips.  It is designed to be able to work over the entire breadth of the 70cm band, like an LPY, but for one band.  My first antenna for the band was a 4 foot boom version of yours.  It has the same ferrite balun.  I was advised by the locals I QSO'd with that the balun was very lossy at high frequencies like 432.  The saving grace of the antenna was that it could be used at either the low end, or 20 MHz higher up near 450.

I also had a short boom 2 meter version of the same antenna, and used it with my 10 watt IC211 from 1981--1983.  I worked everybody I could hear with the antenna at about 25-30 feet with a 50'ish foot run of RG8U foam.  It last flet RF go through it in 1997 during our portable operation in EN67.  I worked K2DRH in EN41 with it from up there.  We were both surprised.

I still have the little 70cm antenna. It has been unused for 20 some years now.  I'll bring it to the CSVHF conference if you'd like.  You could canabalize it, and see if the balun on this one is any better than the one you're using.

By the way, in 1984, I put up stacked CC424Bs and worked 80 grids in short order.  Today, I prefer M2, but your mileage may vary.

73, Tim K0PG

-------------- Original message -------------- 
From: Ray J <ray at w9ray.org> 

> 
> 
> are you sure your RX is ok... 
> 
> 50 miles should be easy on a wet string with 100 watts... is there a 
> mountain between you and the other guy? 
> 
> i run a 19 element k1fo homebrew and it measured out at the expected 
> gain on the range.. i run 100 feet of old 9913 and 10 watts with a old 
> ic-451 and work almost all i can hear 
> 
> W9RAY 
> Ray 
> 
> 
> 
> 
> 
> Carl Estey wrote: 
> 
> >In the Spring of 2005 I obtained a used 16-element 432-Mhz yagii of un-known 
> >design. When I got it up on a 40’ tower and fed it with 65’ of LMR-400 I 
> >found performance over a 50-mile path very poor. Last week I put up a 48’ 
> >piece of Andrew 7/8” Heliax and a 15’ LMR-400 Ultraflex jumper at the 
> >antenna the best I can do on a fifty mile path with 100-watts at both ends 
> >is 20-24 db above the noise – somewhere there is a loss of 40-50 db!! 
> >Physical exam of the antenna shows nothing wrong, which makes me think the 
> >balun is the problem – and it is a ½ diameter six-inch long tube that is 
> >sealed (soldered) on the end with the female N-connector. One the opposite 
> >end of the balun from the N-connector are flat zig-zagged metal straps that 
> >go to several of the elements. Does anyone recognize the design of this 
> >16-element antenna and have any specs on it? 
> > 
> > 
> > 
> >Yesterday someone loaned me a 25-element 17’ 5” long K1FO-style yagii. I 
> >tried the same path with similar poor results. Adjustment of the T-match 
> >failed to provide proper SWR at 432.1 and the lowest point was at 430 Mhz 
> >despite a large amount of re-adjustment. The measurements (made mostly in 
> >the dusk so forgive small errors) are as follows: 
> > 
> > 
> > 
> > 
> >NLRS at mailman.qth.net 
> >http://mailman.qth.net/mailman/listinfo/nlrs 
> > 
> > 
> > 
> > 
> > 
> 
> _______________________________________________ 
> NLRS mailing list 
> NLRS at mailman.qth.net 
> http://mailman.qth.net/mailman/listinfo/nlrs