[TenTec] Tuner

[Richards]

Really?   Please explain.

I ask because Rick DJ0IP and I have both spent considerable time 
researching and building various OCF dipoles to build multiple-band 
antennas which do not depend (or which depend less) on a tuner or 
matchbox than other designs (e.g., a G5RV).

While I have yet to discover the Holy Grail of multi band antennas, the 
articles I read do not mention the limitations your cite.  I am not 
arguing with you - I am just curious to know more, mindful of the 
paucity of other references thereto.

I took care to employ a substantial, heavy duty 4:1 balun specifically 
designed for the precise feed point offset I used - which is at the 
25/75% position, and not at the usual 33/67% position - and this 
provides very low SWR on 40m and 20m and also allows operation on 15 
meters, which is usually not possible with traditional OCF designs.  My 
research and measurements indicate feed point impedance is approx 200 
ohms, substantially lower than the usual 300 ohm figure typically 
realized at the traditional 23/67% offset.

The balun was designed to both transform impedance and block feed line 
radiation as a choke to minimize feed line radiation - not because I 
thought there would be more than a typical dipole, but just in case.

Thus, I ask for an additional gloss on your comment, because I cannot 
imagine how or why one would expect an OCF dipole to exhibit more feed 
radiation than it always has.   That is a curious concept.  I also 
cannot imagine it would be more susceptible to common mode noise than a 
regular coax-fed dipole.  Ergo, pray tell more.

Thanks!
------------------- K8JHR  --------------------


On 7/9/2013 2:21 AM, Jim Brown wrote:

> MANY years ago, when the world was much quieter, and when homes were not
> full of entertainment equipment with Pin One Problems, OCF antennas were
> a very good idea.  That was then, and now is now. And NOW they are a BAD
> idea.
>
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