[TowerTalk] Tuners

[Roger (K8RI)]

On 11/29/2010 2:09 PM, Rick Karlquist wrote:
> Rik van Riel wrote:
>> On 11/27/2010 09:08 PM, Rick Karlquist wrote:
>>
>>> VK1OD did a nice analysis.  Unfortunately, many hams are simply
>>> in a mode of "don't bother me with facts".  They desperately want to
>>> believe in the paradigm of a tuner in the shack and a simple all band
>>> antenna at the other end of the line, such as a plain vertical
>>> conductor,
>>> or a random wire, or a "loop skywire", a "G5RV," or some sort of
>>> "Windom"
>>> antenna.  All continue to live on in ham folklore.
>> The big horizontal loop antenna seems decent, provided it is
>> cut at a length that gives it a good match on not just the
>> primary band but also the others:
>>
>> http://surriel.com/radio/multi-band-hf-loop-antenna
> Are you kidding me?  The pattern breaks up into a multitude
> of lobes on the higher frequencies.  This is the fundamental problem
> with any simple conductor used on many bands with a shack based tuner.
> If you shorten the conductor to fix this problem, then the
> efficiency on the low bands goes way down.  A tuner in the
> shack doesn't really solve this.
Nor would one at the antenna in this case.
I think we are approaching this from the wrong angle.  IE... The typical 
ham puts up the best they can for what's available from a space and cash 
perspective. In that case the tuner in the shack makes a lot of sense.

In my case I use center fed half wave dipoles on 75 and 40.  To cover 
the entire band in either case requires a tuner at the antenna (best but 
most difficult case) or one in the shack (easiest). The same is true for 
the half sloper on 160.  By far the most practical approach is the tuner 
in the shack.  It's what I have and I've never bothered with measuring 
or calculating the loss from the tuner in the shack approach as it's not 
going to change.

73

Roger (K8RI)