[TowerTalk] In Shack Tuner Vs. Remote Tuner for Multi-Band Antennas

[Roger (K8RI) on TT]

On 5/2/2014 7:45 PM, Tony wrote:
> All:
>
> Need some advise on getting the best performance out of a multi-band 
> (80 through 20) wire antenna and tuner. My first option is the 
> in-shack auto-tuner feeding a doublet with a short run of coax and 
> remote balun. The alternative option was to go with a remote 
> auto-tuner mounted near the antenna feeding an 80 meter dipole with 
> ladder line. There would be an 80 foot run of coax from the rig to the 
> remote tuner. I can add dipoles to the remote setup if need be.
>
> I have a 500 watt amplifier so I was considering the 500 watt Elecraft 
> in-shack auto-tuner. The MFJ remote tuner (600 watt version) is 
> reasnably priced, but unfortunately, didn't get good reviews.

If you run 500 watts to a 500 watt tuner, remember that tuners are 
derated for lower impedances.  The loss in good coax (LMR400 or 
9913-7)even with high SWR is quite low. The loss goes up with frequency.

I would get a better tuner rated for at least a KW in the shack.

I use a tuner in the shack for half sloper on 160 and a fan dipole on 75 
and center fed half wave sloper on 40.
The fan dipole takes two current/choke baluns 
http://www.rogerhalstead.com/ham_files/AntennaFeed1.htm and another at 
the tower.  The imbalance of the sloping fan is substantial and take two 
of these baluns to keep RF out of the shack.

I use an AT5K HP in the den and and an AT5K in the shop for legal limit 
amps.  I tune them using a VNA with a pair of A/B switches so I can't 
accidentally feed power into the VNA.  The input to the amp goes to the 
exciter, or the VNA. Output goes to the tuner or dummy load.

73

Roger (K8RI)


>
> Regarding doublets: I plan on using one for portable operation cut for 
> 30 meters with an Elecraft KX3 QRP rig and internal tuner. Any tips on 
> the best ladder line and dipole lengths would be appreciated.
>
> Thanks...
>
> Tony
>
>
>
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