[Elecraft] K2 Tuner and 43 ft. vertical

[Tom W8JI]

> Elecraft. A lot of guys speak negatively about this 
> antenna design and
> show all the reasons it shouldn't work. All I can say is 
> it works for
> me.

Hi Phil,

"Works for me" is fine. No one can argue with that. That 
doesn't mean it has reasonable efficiency. If it had 
reasonable efficiency, it would be very difficult to load up 
on 160 and 80 meters. That's not being negative, it is just 
a simple fact of life.

The base impedance of a 43 foot vertical with a reasonable 
ground on 160 meters is  about 4 - J 750 ohm. To actually 
get 500 watts into that antenna, a tuner at the antenna base 
would have to supply 7900 volts RMS (11 kV peak) at almost 
11 amperes.

The 50-ohm SWR of a 43 foot vertical on 160 is over 100:1. 
On 80 it is at least 50:1 SWR. Plug the impedances into a 
transmission line loss calculator and see how it comes out. 
The loss of 150 feet of Bury Flex is about 20 dB into that 
impedance on 160 meters.

The reason it loads up with a standard tuner is because the 
150 foot transmission line is a huge attenuator pad on 160.

That doesn't mean you won't make contacts, it simply means 
the signal is 20 dB or more weaker than it could be with 
proper matching. Where we might be 30 over 9 with proper 
matching, with a remote tuner it will be 10 over nine or 
less. 20 dB loss (or even more) will still allow contacts. 
It will still make some people quite happy. I'm proud of my 
mobile signal on 160, and I've even worked Australia and 
Japan on CW and Europe on 160 SSB. It is about 1% efficient 
also, and it makes me quite happy. I'd be happier with 
another 20 dB, but that isn't possible with an 8-foot long 
mobile antenna on 160.

73 Tom