[TowerTalk] 80M Inverted V - CW and SSB

[Steve Hunt]

It's worth mentioning that Jim's method needs the dipole to be at a 
reasonable height - 40ft or more - to avoid having a low resonant 
feedpoint resistance. Once you go much lower than 40ft, and the resonant 
impedance falls below about 55 Ohms, the SWR will stay *above* 2:1 all 
across the band.

Steve G3TXQ




On 21/10/2013 17:44, Jim Brown wrote:
> On 10/21/2013 2:50 AM, Doug Scribner wrote:
>> I'd like to find a quick way to switch between the CW and Phone 
>> portions of the band.
>
> There's an easy method to obtain a broadband match using transmission 
> lines. Carefully tune the antenna for 3675 kHz. Feed it with a half 
> wave, or a full wave, of 50 ohm line beginning at the antenna, then a 
> quarter wave of 75 ohm cable, then as much 50 ohm cable as you need to 
> get to the shack. Measure those lengths carefully as a stub at 3675 
> using something like a MFJ 259. This will give you a match in the 
> shack below 2:1 from 3500 to 3900. Make that first 50 ohm length the 
> least number of half waves that will still reach the shack.  This 
> method is shown in detail in a presentation I did last year at Pacificon.
>
> http://k9yc.com/PacificonSmithChart.pdf 
> <http://audiosystemsgroup.com/PacificonSmithChart.pdf>
>
> 73, Jim K9YC
>
>