[TowerTalk] Mono Band delta feed question

[Herbert Schoenbohm]

did you correct the length of the stub b the RG59 velocity factor?  Plus 
the stub length is different for foam coax. Since RG-59 is cheap i would 
experiment my making the stub too long and then trimming it.   Before 
you do anything check the antenna without a stub connected with your 
analyzer or at the end of a 1/2 wave (electrical) length of coax to see 
what the actual antenna impedance you need to match.  Make sure then 
that the wire in the delta loop is close to resonance as that will have 
a major impact on the feed impedance. When you get in the ballpark I 
would also recommend a current balun at the feed point. Depending on the 
way the feed-line dresses away from the antenna should also be taken 
into consideration.  I believe a corner fed delta has a impedance lower 
than a bottom center fed.  You might check your modeling on that.

Herb, KV4FZ


On 11/30/2016 2:02 PM, R. David Eagle via TowerTalk wrote:
> Hello all, I am working on a second mono band delta for my QTH and this time it will be for 80 meters.  I am pretty impressed with the 40 meter version I built but I am suspicious that maybe my RG59 quarter wave stub is incorrect.  I decided to sweep it yesterday with my antenna analyzer and noticed where my antenna is resonant, I was getting around 36 ohms.
> My question to you all is if you are running over 500 watts what seems to be the most "efficient" means of matching the feedpoint....cored balun, coax stub, etc???
> Any help would be appreciated.
> DaveKB8NNU
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