Re: K2 Tuner and 43 ft. vertical

[Phillip Zminda]

I have a Zero-Five 43 ft. verttcal and a K2. I use the KAT-2 built-in  
tuner with it. It tunes on all bands 80 through 10 meters with no  
difficulty. I don't have the 160 board in the K2 so can't comment on  
160 with this tuner. I have about 50 radials, most 43 ft long and a  
little over 150 ft of Bury-Flex coax. This antenna would not tune well  
on 80 and didn't tune on 160 at all  with an LDG AT100Pro  auto-
tuner.  With a Palstar  tuner I can tune 160 easily with this antenna.  
I suspect that the K2 tuner would be OK on 160 also.

As for the antenna, it's built like a tank. It's very easy to assemble  
and works well for me chasing DX on 40 and 80. If you have questions,  
you can speak directly with Tom the owner, just like dealing with  
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.

Phil N3ZP
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[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

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