[Elecraft] 43' Vertical - mine is 31ft

[Dyarnes]

Wim DeWilder posted:


I have a 31 foot vertical myself (S9 V31) and since I have the KPA500 I
use the 600 WATT  MFJ remote auto tuner.
With about 8 radials of 30 ft it works well on 40m - 10m.
The MFJ can't tune it on 80m but the internal K3 tuner does.
Feedline is 100ft of RG213

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Wim,

Is the MFJ tuner still "in line" when you tune with the K3 on 80 meters?

It seems to me that you are loading a 40 meter vertical on 80 meters, which 
means your feedpoint impedance is probably very high--maybe a few thousand 
ohms???  That's a pretty large order for most auto-tuners.

The K3 tuner is darn good, and just might give you a match of some sort, but 
that's a stretch for it as well.  10:1 is kind of the spec limit, and I 
think you may be exceeding that.  Still, I'm not sure what it might be 
tuning if you don't have the MFJ bypassed.

Also, that 100 feet of feedline, even though it's pretty good stuff, is 
probably giving you a lot of loss since you apparently don't have a good 
match at the base.  As I understand it, if you don't get pretty close to 50 
ohms at the base of the antenna, then your coax will just increase your 
losses considerably over and above what it would normally cause due to the 
length of the run.

I can "tune" my R8 vertical on 80 meters (and even 160 meters) just using 
the K3's ATU, and a run of about 50 feet of coax.  However, I am certain 
that my efficiency is crap!  I've only tried this a couple of times because 
it scares me to death to try it!

Dave W7AQK